This PDF file contains the front matter associated with SPIE Proceedings Volume 8031, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

True nanotechnology, defined as the ability to reliably and repeatably fabricate nanostructures with controlled differences in size, shape, and orientation at precise substrate locations, currently does not exist. There are many examples demonstrating the capability to grow, deposit, and manipulate nanometer-sized features, but typically these techniques do not allow for controllable manufacturing of individual structures. To bridge this gap and to unlock the true potential of nanotechnology for defense sensing applications, the Defense Advanced Research Projects Agency (DARPA) launched the Tip-Based Nanofabrication (TBN) research program with the intent of achieving controlled manufacturing of nanostructures using functionalized AFM cantilevers and tips. This work describes the background, goals, and recent advances achieved during the multi-year TBN program.

Massively parallel scanning-probe based methods have been used to address the challenges of nanometer to millimeter scale printing for a variety of materials and mark a step towards the realization of a "desktop fab." Such tools enable simple, flexible, high-throughput, and low-cost nano- and microscale patterning, which allow researchers to rapidly synthesize and study systems ranging from nanoparticle synthesis to biological processes. We have developed a novel scanning probe-based cantilever-free printing method termed polymer pen lithography (PPL), which uses an array of elastomeric tips to transfer materials (e.g. alkanethiols, proteins, polymers) in a direct-write manner onto a variety of surfaces. This technique takes the best attributes of dip-pen nanolithography (DPN) and eliminates many of the disadvantages of contact printing. Various related techniques such as beam pen lithography (BPL), scanning probe block copolymer lithography (SPBCL), and hard-tip, soft spring lithography (HSL) are also discussed.

Nanometer-scale patterning of graphite and graphene has been accomplished through local anodic oxidation using an AFM tip. The underlying mechanism is explained. To date, protrusions, holes, trenches, and even words have been patterned in HOPG over scales ranging from 1nm² to 1mm² and depths ranging from sub nm to as deep as 200nm with less than 5 nm variation on the feature size and placement. This same method has also been applied to CVD-grown graphene providing a resist-free process for patterning graphene at the single nanometer scale. This capability could provide a method to rival e-beam lithography resolution but without any pre- or post-processing.

We present progress towards scalable, high precision nanofabrication in a variety of materials using heated Atomic Force Microscope (AFM) probes. Temperature control of a heated AFM tip allows nanometer scale thermochemical patterning, deposition of thermoplastic polymers, and surface melting. The challenges that must be overcome to scale such a technology to industrial-scale manufacturing include tip wear, thermal and mechanical control of the cantilever, chemical reaction control at the tip-surface interface, and fabrication throughput. To mitigate tip wear, we have integrated nanocrystalline diamond films onto our heated AFM probe tip. Such diamond tips are extremely resistant to wear and fouling at a self-heating temperature of 400 C and load force of 200 nN over long distances. To improve cantilever temperature control, a closed loop feedback control was designed to allow for 0.2 C precision temperature control during nanolithography. Electrohydrodynamic jetting controls the deposition of polyethylene onto a heated probe tip. Finally, to address throughput, we have fabricated cantilever arrays having independent temperature control and integrated them into a commercial AFM system. We show these advances by patterning thousands of nanostructures of polyethylene and poly(3-dodecylthiophene), with cumulative length more than 2 mm and patterning accuracy better than 50 nm.

Recent research results are presented where lasers of different pulse durations and wavelengths have been coupled to near-field-scanning optical microscopes (NSOMs) through apertured bent cantilever fiber probes and atomic force microscope (AFM) tips in apertureless configurations. Experiments have been conducted on the surface modification of metals and semiconductor materials. By combining nanoscale ablative material removal with subsequent chemical etching steps, ablation nanolithography and patterning of fused silica and crystalline silicon wafers has been demonstrated. Confinement of laser-induced crystallization to nanometric scales has also been shown. In-situ observation of the nanoscale materials modification was conducted by coupling the NSOM tips with a scanning electron microscope (SEM). Nucleation and growth of semiconductor materials have been achieved by laser chemical vapor deposition (LCVD) at the nanoscale level. Locally selective growth of crystalline silicon nanowires with controlled size, heterogeneity and nanometric placement accuracy has been accomplished.

Semiconductor nanomembranes, extremely thin (<10 to ~1000 nm) single-crystal sheets, promise considerable new science and technology. They are flexible, they are readily transferable to other hosts and conform and bond easily, and they can take on a large range of shapes (tubes, spirals, ribbons, wires) via appropriate strain engineering and patterning. The ready ability to stack membranes allows the integration of the properties of different materials and/or orientations. A brief review of nanomembrane fabrication and manipulation with a view toward different types of applications is provided.

Solid-state thermal neutron detectors are desired to replace ³He tube tube-based technology for the detection of special nuclear materials. ³He tubes have some issues with stability, sensitivity to microphonics and very recently, a shortage of ³He. There are numerous solid-state approaches being investigated that utilize various architectures and material combinations. Our approach is based on the combination of high-aspect-ratio silicon PIN pillars, which are 2 μm wide with a 2 μm separation, arranged in a square matrix, and surrounded by ¹⁰B, the neutron converter material. To date, our highest efficiency is ~ 20 % for a pillar height of 26 μm. An efficiency of greater than 50 % is predicted for our device, while maintaining high gamma rejection and low power operation once adequate device scaling is carried out. Estimated required pillar height to meet this goal is ~ 50 μm. The fabrication challenges related to ¹⁰B deposition and etching as well as planarization of the three-dimensional structure is discussed.

THz and submillimeter wave technology is of great interest to DHS S&T due to the non-ionizing and clothing penetrating properties of the spectral region. Imaging in the region allows for standoff imaging of concealed threats such as Improvised Explosive Devices (IED) at operationally relevant distances. DHS S&T is investing in this area with the development of components such as detectors and sources for active imaging as well as full sensor systems in the future. The fundamental characterization of the region is also being explored with DHS funding by imaging well-characterized rough surface scattering targets. Analysis of these images will yield data to be used in evaluating assumptions currently made in current performance models. This along with the relevant field applications will be addressed.

The combination of atmospheric propagation windows and notches, in conjunction with the rich spectral signatures of many materials in the millimeter-wave through THz region of the electromagnetic spectrum, make sensing and imaging in this spectral range of particular interest in security, defense, and medical spheres. For sensing and imaging systems, high-sensitivity and low-noise detectors are key components; micro- and nano-scale devices are especially promising for detectors since small device scales naturally lead to lower device capacitances (and thus increased operational frequency) while the exploitation of quantum mechanical tunneling at the nanoscale offers significant potential for improving intrinsic detector performance. We report recent developments in InAs/AlSb/GaSb heterostructure backward tunnel diodes for millimeter-wave through THz detection and imaging applications. These devices have demonstrated measured room-temperature curvatures of 47 V^-1, exceeding the fundamental limitation of q/kT=38.5 V^-1 for Schottky diodes. Since detector sensitivity is proportional to curvature, these increases in curvature translate to improved sensitivity; unmatched sensitivities of 4600 V/W at 94 GHz have been measured, and sensitivities of nearly 50,000 V/W are projected under conjugately-matched conditions. These devices also offer extremely low noise performance; we report projected NEP values below 0.2 pW/Hz^1/2 at 94 GHz for conjugately-matched detectors. A challenging issue in the design of optimized interband tunneling-based devices is the difficulty in accurately simulating and modeling the devices. We have developed a numerical model based on self-consistent solution of the Poisson/Schrodinger equations coupled with 8-band k•p band structure and transfer-matrix calculations that agrees well with experimental device results and enables projection of performance for novel structures. This simulation framework suggests several promising avenues for further device performance improvement, and provides a means to optimize detector performance for applications.

We describe the fabrication of an Orotron driven by a sheet beam of electrons. The sheet beam is generated by a carbon nanotube field emission electron gun, which is less than 2 mm in total thickness. The orotron cavity is 2 cm long and 1 cm wide, and houses a microfabricated Smith-Purcell grating which generates the THz radiation. The sheet beam is 5 μm thick and 6 mm wide, and it travels within 15 μm of the top surface of the Smith-Purcell grating for the length of the cavity. The Orotron is discretely tunable, which means that there are a number of cavity resonances that can be driven by changing the energy of the beam such that for the period of the Smith-Purcell grating the cavity is driven on one of the resonances. For this work, a target frequency of 0.5 THz, corresponding to a beam energy of 3 keV, was used.

We review our previous work to develop an uncooled THz detector capable of achieving an NEΔT ~0.5K at 30Hz frame rate and describe our approach to develop a staring THz camera based on a 2D array of such detectors. Both predicted and measured results of performance metrics (responsivity, NEP, response time, spectral bandwidth, NEΔT) are presented. The measured performance agrees reasonably well with predictions and is consistent with attaining our NEΔT goal. Thus far, 1x4 detector arrays have been fabricated, and 1x8 focal plane arrays have been developed and tested. We briefly discuss our vision to achieve a128x128 detector array needed for a practical staring THz imager and describe the technology challenges needed to realize it.

The quantum cascade laser (QCL) is currently the only solid-state source of coherent THz radiation capable of delivering more than 1 mW of average power at frequencies above ~ 2 THz. This power level combined with very good intrinsic frequency definition characteristics make QCLs an extremely appealing solid-state solution as compact sources for THz applications. I will present results on integrating QCLs with passive rectangular waveguides for guiding and controlling the radiation emitted by the QCLs and on the performance of a THz integrated circuit combining a THz QCL with a Schottky diode mixer to form a heterodyne receiver/transceiver.

THz technology has a rich history of use in the field of interstellar molecule identification where a variety of molecule specific vibrational and rotational spectroscopic signatures exist and has been aggressively investigated for use in advanced radar applications because of the immediate improvement in object resolution obtained at higher frequencies. Traditionally, high power THz systems have relied upon millimeter wave sources and frequency multiplication techniques to achieve acceptable output power levels, while lower power, table top spectroscopic systems, have relied on broadband incoherent light sources. With the advent of high power lasers, advances in non-linear optics, and new material systems, a number of promising techniques for the generation, detection and manipulation of THz radiation are currently under development and are considered the enabling technologies behind a variety of advanced THz applications. This work presents a programmatic overview of current trends in THz technology of interest to a variety of government organizations. It focuses on those techniques currently under investigation for the generation and detection of THz fields motivated, for example, by such diverse applications as metamaterial spectroscopy, TH imaging, long standoff chem/bio detection and THz communications. Examples of these new techniques will be presented which in turn will motivate the need for the characterization of application specific active and passive THz components.

The characterization of anhydrous and hydrated forms of materials is of great importance to science and industry. Water content poses difficulties for successful identification of the material structure by THz radiation. However, biological tissues and hydrated forms of nonorganic substances still may be investigated by THz radiation. This paper outlines the range of possibilities of the above characterization, as well as provides analysis of the physical mechanism that allows or prevents penetration of THz waves through the substance. THz-TDS is used to measure the parameters of the characterization of anhydrous and hydrated forms of organic and nonorganic samples. Mathematical methods (such as prediction models of time-series analysis) are used to help identifying the absorption coefficient and other parameters of interest. The discovered dependencies allow designing techniques for material identification/characterization (e.g. of drugs, explosives, etc. that may have water content). The results are provided.

We present results on design, fabrication, and characterization of hot-electron bolometers based on low-mobility two-dimensional electron gas (2DEG) in AlInN/GaN and AlGaN/GaN heterostructures. Electrical and optical characterization of our Hot Electron Bolometers (HEBs) show that these sensors combine (i) high coupling to incident THz radiation due to Drude absorption, (ii) significant electron heating by the THz radiation due to small value of the electron heat capacity, (iii) substantial sensitivity of the device resistance to the heating effect. A low contact resistance (below 0.5 Ω·mm) achieved in our devices ensures that the THz voltage primarily drops across the active region. Due to a small electron momentum relaxation time, the inductive part of the impedance in our devices is large, so these sensors can be combined with standard antennas or waveguides. In the capacity of the THz local oscillator (LO) for heterodyne THz sensing, we fabricated AlGaAs/GaAs quantum cascade lasers (QCLs) with a stable continuous-wave single-mode operation in the range of 2.5-3 THz. Spectral properties of the QCLs have been studied by means of Fourier transform spectroscopy. It has been demonstrated that the spectral purity of the QCL emission line doesn't exceed the spectrometer resolution limit at the level of 0.1 cm^-1 (3 GHz). Discrete spectral tuning can be achieved using selective devices; fine tuning can be done by thermally changing the refractive index of the material and by applied voltage. Compatibility of the low-mobility 2DEG microbolometers with QCLs in terms of LO power requirements, spectral coverage, and cooling requirements makes this technology especially attractive for THz heterodyne sensing.

Traditional THz electronics is using nonlinear properties of Schottky diodes for THz detectors and mixers and Gunn diodes driving frequency multiplier Schottky diode chains. Recently, ultra-short channel silicon CMOS and nitridebased transistors have demonstrated THz performance. New approaches use excitations of electron density in FET channels - called plasma waves - to generate and detect THz radiation, and extremely high sheet electron density in short channel AlN/GaN based HEMTs makes them especially suitable for applications in THz plasmonic devices.

Terahertz quantum cascade (QC) lasers are well suited for the exploration of active metamaterial concepts in the terahertz frequency range. Terahertz composite right/left handed (CRLH) transmission line metamaterials can be integrated with quantum cascade laser gainmaterial in order to compensate for losses, and enable laser waveguides with new functionality. In particular, we consider the use of metamaterial transmission lines as travelling wave antennas. After presenting the characteristics of a 2.5 THz quantum-cascade laser, calculated radiation characteristics and beam patterns for a leaky-wave antenna based upon a balanced 1D CRLH transmission line waveguide are shown.

The Naval Prototype Optical Interferometer (NPOI) is the longest baseline at visible wavelengths interferometer in the world. The astronomical capabilities of such an instrument are being exploited and recent results will be presented. NPOI is also the largest optical telescope belonging to the US Department of Defense with a maximum baseline of 435 meter has a resolution that is approximately 181 times the resolution attainable by the Hubble Space Telescope (HST) and 118 times the resolution attainable by the Advanced Electro-Optical System (AEOS). It is also the only optical interferometer capable of recombining up to six apertures simultaneously. The NPOI is a sparse aperture and its sensitivity is limited by the size of the unit aperture, currently that size is 0.5 meters. In order to increase the overall sensitivity of the instrument a program was started to manufacture larger, 1.4 meter, ultra-light telescopes. The lightness of the telescopes requirement is due to the fact that telescopes have to be easily transportable in order to reconfigure the array. For this reason a program was started three years ago to investigate the feasibility of manufacturing Carbon Fiber Reinforced Polymer (CFRP) telescopes, including the optics. Furthermore, since the unit apertures are now much larger than r0 there is a need to compensate the aperture with adaptive optics (AO). Since the need for mobility of the telescopes, compact AO systems, based on Micro-Electro-Mechanical-Systems (MEMS), have been developed. This paper will present the status of our adaptive optics system and some of the results attained so far with it.

Thin-shelled composite mirrors have been recently proposed as both deformable mirrors for aberration correction and as variable radius-of-curvature mirrors for adaptive optical zoom. The requirements on actuation far surpass those for other MEMS or micro-machined deformable mirrors. We will discuss recent progress on developing the actuation for these mirrors, as well as potential applications.

We are developing a highly miniaturized trapped ion clock to probe the 12.6 GHz hyperfine transition in the ¹⁷¹Yb⁺ ion. The clock development is being funded by the Integrated Micro Primary Atomic Clock Technology (IMPACT) program from DARPA where the stated goals are to develop a clock that consumes 50 mW of power, has a size of 5 cm³, and has a long-term frequency stability of 10^-14 at one month. One of the significant challenges will be to develop miniature single-frequency lasers at 369 nm and 935 nm and the optical systems to deliver light to the ions and to collect ion fluorescence on a detector.

Polarimetric imaging captures the polarization state of light from all the points of a scene. Snapshot polarimetric imaging collects the Stokes' parameters spatial distribution simultaneously. We will discuss state-of-the-art achievements and some fundamental diffraction limitations in polarimetric imaging with an array of micro-components. We will also look at the natural vision system of the mantis shrimp, with many of these same sensing abilities. The evolved and exquisite vision system possesses a recently-discovered circular polarization capability. This comprehensive polarization vision may enable imaging/communicating advantages in the underwater environment as well as more general turbid environments such as smoke and fog.

We present a review on recent advancements in rolled-up optical components created using strain engineering. A look at optical and optofluidic resonators as well as the hyperlens and an optical fiber metamaterial device is given. These individual ultra-compact components allow researchers to develop large arrays of a future highly-integrated biological sensing device known as a lab-in-a-tube. These lab-in-a-tube devices would allow for a very large parallel but individual analysis of thousands of cells, molecules and bacteria on a single chip.

We have integrated electronic, optical, magnetic, thermal and fluidic devices into systems to construct useful analysis tools. Over the past several years, we have developed soft lithography approaches to define microfluidic systems in which pico-Liter volumes can be manipulated. These fluidic delivery systems have more recently been integrated with optical and electronic devices. We have also developed thermal control systems with fast (>50oC/s) cooling and heating ramp speeds and excellent accuracy.

We examine light-trapping in thin crystalline silicon periodic nanostructures for solar cell applications. Using group theory, we show that light-trapping can be improved over a broad band when structural mirror symmetry is broken. This finding allows us to obtain surface nanostructures with an absorptance exceeding the Lambertian limit over a broad band at normal incidence. Further, we demonstrate that the absorptance of nanorod arrays with symmetry breaking not only exceeds the Lambertian limit over a range of spectrum but also closely follows the limit over the entire spectrum of interest for isotropic incident radiation. These effects correspond to a reduction in silicon mass by two orders of magnitude, pointing to the promising future of thin crystalline silicon solar cells.

Photonic nanostructures with widely, rapidly and reversibly tunable diffraction in the visible and near-infrared spectrum can be created through a magnetic field assisted assembly strategy. We first describe the mechanism for the formation of dynamic photonic chains and the tuning of the diffraction colors using an external magnetic field. Then we discuss the fixation of photonic chains in a solid polymer matrix through combining instant magnetic assembly with a rapid UV polymerization process which allows us to confirm the chaining structures. Finally, we demonstrate several applications of magnetically tunable photonic nanostructures for security and sensing devices, high resolution patterning of multiple structural colors.

The U.S. Army has strong interests in nanoscale architectures that enable enhanced extraction and controllable multiplication of the THz/IR regime spectral signatures associated with specific bio-molecular targets. Emerging DNAbased nano-assemblies (i.e., either materials or structural devices) will be discussed that realize novel sensing paradigms through the incorporation of organic and/or biological molecules such that they effect highly predictable and controllable changes into the electro-optical properties of the resulting superstructures. Results will be given to illustrate the utility of functionalized DNA materials in biological (and chemical) sensing, and to demonstrate how the basic science can be leveraged to study and develop synthetic antibodies, reporters and vaccines for future medical applications.

The engineered deposition of self-assembled coatings of micro- and nano-particles on solid surfaces has applications in photonic crystals, optoelectronic devices, sensors, waveguides and antireflective coatings. Besides lithographic, etching or vapor deposition methods, these coatings can be self-assembled on small (<O(1mm²) circular surfaces by the deposition and drying of drops on surfaces, or on larger (O(cm²)) rectangular surfaces by pulling an evaporating meniscus, in a process called convective deposition. Both processes involve multiscale phenomena such as transient fluid dynamics with wetted regions, DLVO forces, heat and mass transfer in the deforming geometry of a complex fluid. These competing phenomena control the self-assembly of micro- and nano-particle deposits. A simple phase diagram is presented, that describes the mechanisms governing the transition between different patterns during the evaporation of a drop. A multiphysics modeling of the convective deposition process is also presented, which provides insight on ways to improve the reliability of the deposition process. Finally, an outlook is given on technical applications related to the use of convective deposition techniques in manufacturing.

Graphene is well known for its outstanding electronic, thermal, and mechanical properties, and has recently gained tremendous interest as a nanomaterial for optoelectronic devices. We review our recent efforts on exfoliated graphene with a particular focus on the influence of graphene's chiral edges on the electronic and optical properties. We first show that Raman spectroscopy can not only be used for layer metrology but also to monitor the composition of graphene's zigzag/armchair edges. To elucidate the role of the localized edge state density, we fabricated dye sensitized antidot superlattices, i.e. nanopatterned graphene. The fluorescence from deposited dye molecules was found to quench strongly as a function of increasing antidot filling fraction, whereas it was enhanced in unpatterned but electrically back-gated samples. This contrasting behavior is strongly indicative of a built-in lateral electric field of up to 260 mV accounting for p-type doping as well as fluorescence quenching due to dissociation of electron-hole pairs from attached dye molecules. Our study provides new insights into the interplay of localized edge states in antidot superlattices and the resulting band bending, which are critical properties to enable novel applications of nanostructured graphene for light harvesting and photovoltaic devices.

This paper describes the results of a Joint Experiment performed on behalf of the MAST CTA. The system developed for the Joint Experiment makes use of three robots which work together to explore and map an unknown environment. Each of the robots used in this experiment is equipped with a laser scanner for measuring walls and a camera for locating doorways. Information from both of these types of structures is concurrently incorporated into each robot's local map using a graph based SLAM technique. A Distributed-Data-Fusion algorithm is used to efficiently combine local maps from each robot into a shared global map. Each robot computes a compressed local feature map and transmits it to neighboring robots, which allows each robot to merge its map with the maps of its neighbors. Each robot caches the compressed maps from its neighbors, allowing it to maintain a coherent map with a common frame of reference. The robots utilize an exploration strategy to efficiently cover the unknown environment which allows collaboration on an unreliable communications channel. As each new branching point is discovered by a robot, it broadcasts the information about where this point is along with the robot's path from a known landmark to the other robots. When the next robot reaches a dead-end, new branching points are allocated by auction. In the event of communication interruption, the robot which observed the branching point will eventually explore it; therefore, the exploration is complete in the face of communication failure.

There are many examples in nature where large groups of individuals are able to maintain three-dimensional formations while navigating in complex environments. This paper addresses the development of a framework and robot controllers that enable a group of aerial robots to maintain a formation with partial state information while avoiding collisions. The central concept is to develop a low-dimensional abstraction of the large teams of robots, facilitate planning, command, and control in a low-dimensional space, and to realize commands or plans in the abstract space by synthesizing controllers for individual robots that respect the specified abstraction. The fundamental problem that is addressed in this paper relates to coordinated control of multiple UAVs in close proximity. We develop a representation for a team of robots based on the first and second statistical moments of the system and design kinematic, exponentially stabilizing controllers for point robots. The selection of representation permits a controller design that is invariant to the number of robots in the system, requires limited global state information, and reduces the complexity of the planning problem by generating an abstract planning and control space determined by the moment parameterization. We present experimental results with a team of quadrotors and discuss considerations such as aerodynamic interactions between robots.

Unmanned micro air vehicles (MAVs) will play an important role in future reconnaissance and search and rescue applications. In order to conduct persistent surveillance and to conserve energy, MAVs need the ability to land, and they need the ability to enter (ingress) buildings and other structures to conduct reconnaissance. To be safe and practical under a wide range of environmental conditions, landing and ingress maneuvers must be autonomous, using real-time, onboard sensor feedback. To address these key behaviors, we present a novel method for vision-based autonomous MAV landing and ingress using a single camera for two urban scenarios: landing on an elevated surface, representative of a rooftop, and ingress through a rectangular opening, representative of a door or window. Real-world scenarios will not include special navigation markers, so we rely on tracking arbitrary scene features; however, we do currently exploit planarity of the scene. Our vision system uses a planar homography decomposition to detect navigation targets and to produce approach waypoints as inputs to the vehicle control algorithm. Scene perception, planning, and control run onboard in real-time; at present we obtain aircraft position knowledge from an external motion capture system, but we expect to replace this in the near future with a fully self-contained, onboard, vision-aided state estimation algorithm. We demonstrate autonomous vision-based landing and ingress target detection with two different quadrotor MAV platforms. To our knowledge, this is the first demonstration of onboard, vision-based autonomous landing and ingress algorithms that do not use special purpose scene markers to identify the destination.

This paper presents the development of a static estimator for obtaining state information from optic flow and radar measurements. It is shown that estimates of translational and rotational speed can be extracted using a least squares inversion. The approach is demonstrated in a simulated three dimensional urban environment on an autonomous quadrotor micro-air-vehicle (MAV). The resulting methodology has the advantages of computation speed and simplicity, both of which are imperative for implementation on MAVs due to stringent size, weight, and power requirements.

Autonomous small robotic platforms require a suite of sensor to navigate and function in complex environment. Due to limited space, onboard power, and processing capability these sensors must be low mass, compact size, low power, and run with minimal processing resources. We are in the process of developing a compact and low-power imaging mm-wave radar system for small autonomous robotic platforms operating at Y-band to allow for navigation and obstacle detection in conditions that make the use of passive optical sensors difficult or impossible. The radar system is being fabricated and assembled using silicon micromachining technique with the overall mass of 5 grams, peak power of 200 mW, and operational power of 6.7 mW for one frame per second update rate, field of view of ± 25°, angular resolution of 2°, range resolution of 37.5cm, and range of 400m. The beam steering is accomplished by frequency scanning and the range resolution is obtained from the standard FMCW technique utilizing a chirped signal waveform with step discontinuities. This paper will present the overall architecture of this radar system in addition to the phenomenological investigation of scattering from obstacle in indoor environment. It is also shown how radar images taken from indoor scenes can be interpreted and utilized to create the interior layout of a building.

Nanometer CMOS processes have proven to be surprisingly effective for analog and RF design. New design techniques have greatly improved the efficiency of ADCs and RF interfaces and also enabled new flexibility. Moving to techniques that are more digital in nature allows fast and easy changes in architecture and performance. Furthermore, from the standpoint of energy efficiency there can be fundamental advantages to processing signals in the digital domain. This paper discusses digital dominant nanometer CMOS transmitter and receiver schemes that are the basis of flexible efficient wireless transceivers for the MAST platforms.

This paper presents recent work on reconfigurable all-digital radio architectures. We leverage the flexibility and scalability of synthesized digital cells to construct reconfigurable radio architectures that consume significantly less power than a software defined radio implementing similar architectures. We present two prototypes of such architectures that can receive and demodulate FM and FRS band signals. Moreover, a radio architecture based on a reconfigurable alldigital phase-locked loop for coherent demodulation is presented.

Radio signal strength (RSS) is a reasonable proxy for link quality, but its accurate estimation requires frequency and spatial diversity due to fluctuation caused by fading. We consider a Rayleigh/Rician fading model, and gather RSS measurements during motion in a complex environment to enable gradient estimation. Using the RSS gradient, we develop control laws to track active sources. These may be used to establish and preserve connectivity among collaborative autonomous agents, to locate and approach radio sources, as well as deploying agents to assist mobile ad hoc networks (MANETs).

Ad hoc communication among small robotic platforms in complex indoor environment is further challenged by three limiting factors: 1) limited power, 2) small size antennas, and 3) near-ground operation. In complex environments such as indoor scenarios often times the line-of-sight communication cannot be established and the wireless connectivity must rely on multi-path propagation. As a result, the propagation path-loss is much higher than free-space, and more power will be needed to obtain the need coverage. Near ground operation also leads to increased path-loss. To maintain the network connectivity without increasing the required power a novel high gain miniaturized radio repeater is presented. Unlike existing repeater systems, this system utilizes two closely spaced low profile miniaturized planar antennas capable of producing omnidirectional and vertical radiation patterns as well as a channel isolator layer that serves to decouple the adjacent antennas. The meta-material based channel isolator serves as an electromagnetic shield, thus enabling it to be built in a sub-wavelength size of 0.07λ0 ² × λ0/70, the smallest repeater ever built. Also wave propagation simulations have been conducted to determine the required gain of such repeaters so to ensure the signal from the repeater is the dominant component. A prototype of the small radio repeater is fabricated to verify the design performance through a standard free-space measurement setup.

This paper reviews currently recognized needs for advances in precision navigation and timing technology, summarizes ongoing efforts, and discusses future technological developments being pursued under the aggregated DARPA/MTO Microtechnology for Positioning, Navigation, and Timing (micro-PNT) program.

Recent years have witnessed breakthrough researches in micro- and nano-mechanical resonators with small dissipation. Nano-precision micromachining has enabled the realization of integrated micromechanical resonators with record high Q and high frequency, creating new research horizons. Not too long ago, there was a perception in the MEMS community that the maximum f.Q product of a microresonator is limited to a frequency-independent constant determined by the material properties of the resonator. In this paper, the contribution of phonon interactions in determining the upper limit of f.Q product in micromechanical resonators will be discussed and shown that after certain frequency, the f.Q product is no longer constant but a linear function of frequency. This makes it possible to reach very high Qs in GHz micro- and nano-mechanical resonators and filters. Contributions of other dissipation mechanisms such as thermoelastic damping and support loss in the quality factor of a microresonator will be discussed as well.

Single monolayers of molecules were found to strongly affect the quality factors of MHz-range torsional silicon resonators. By changing a single monolayer of molecules on the surface of a 5-μm-wide, 250-nm-thick silicon resonator - less than 0.07% of the total mass - the quality factor of the resonator was increased by 70%. In contrast, the standard commercial coating, a thin layer of silicon oxide, dissipates at least 75% of the mechanical energy in similarly sized resonators. Since the relative importance of these surface chemical losses scales with the resonator's surface-to-volume ratio, the development of low-loss, stable surface chemistries will be important for the production of high-performance micro- and nano-mechanical devices.

The contribution is directed to providing accurate simulation and approximation of the Q-factor determined by thermalelastic damping in complex micro-electromechanical (MEM) resonators. The base model created is presented as a system of partial differential equations, which describe the elastic and thermal phenomena in the MEM structure. The FEM calculations were performed by using COMSOL Multiphysics software. The model was verified by comparing numerically and analytically obtained damped modal properties of a MEM cantilever resonator. The comparison of calculated and experimentally obtained resonant frequencies and Q-factor values indicated a good agreement of tendencies of change of the quantities against temperature. Investigation of longitudinal and bending vibration modes in 3D of a beam resonators was accomplished by taking into account the layered structure of the resonator and the influence of the geometry of the clamping zone. Modal properties of rectangle- and ring-shaped bulk-mode MEM resonators were examined, too.

In micro- and nano-scale resonators, a key performance metric is the quality factor (Q), which is the ratio of stored mechanical energy to the energy dissipated. In well-optimized designs, Q is limited by thermal physics and specific energy loss mechanisms including thermoelastic, Akhieser, and Landau-Rumer damping. The relative importance of each effect depends on the time and length scales dominating the device. Most published analyses focus on special regimes where only one mechanism dominates, though real devices may operate in regimes that are not the limiting case. This paper presents thermal damping across the range of frequency and length scales. Data on acoustic loss is compared with theory.

While Sandia initially was motivated to investigate emergent microsystem technology to miniaturize existing macroscale structures, present designs embody innovative approaches that directly exploit the fundamentally different material properties of a new technology at the micro- and nano-scale. Direct, hands-on experience with the emerging technology gave Sandia engineers insights that not only guided the evolution of the technology but also enabled them to address new applications that enlarged the customer base for the new technology. Sandia's early commitment to develop complex microsystems demonstrated the advantages that early adopters gain by developing an extensive design and process tool kit and a shared awareness of multiple approaches to achieve the multiple goals. As with any emergent technology, Sandia's program benefited from interactions with the larger technical community. However, custom development followed a spiral path of direct trial-and-error experience, analysis, quantification of materials properties at the micro- and nano-scale, evolution of design tools and process recipes, and an understanding of reliability factors and failure mechanisms even in extreme environments. The microsystems capability at Sandia relied on three key elements. The first was people: a mix of mechanical and semiconductor engineers, chemists, physical scientists, designers, and numerical analysts. The second was a unique facility that enabled the development of custom technologies without contaminating mainline product deliveries. The third was the arrival of specialized equipment as part of a Cooperative Research And Development Agreement (CRADA) enabled by the National Competitiveness Technology Transfer Act of 1989. Underpinning all these, the program was guided and sustained through the research and development phases by accomplishing intermediate milestones addressing direct mission needs.

This paper describes recent advances in the MEMS performance challenges with emphases on packaging and shock tests. In the packaging area, metal to metal bonding processes have been developed to overcome limitations of the glass frit bonding by means of two specific methods: (1) pre-reflow of solder for enhanced bonding adhesion, and (2) the insertion of thin metal layer between parent metal bonding materials. In the shock test area, multiscale analysis for a MEMS package system has been developed with experimental verifications to investigate dynamic responses under drop-shock tests. Structural deformation and stress distribution data are extracted and predicted for device fracture and in-operation stiction analyses for micro mechanical components in various MEMS sensors, including accelerometers and gyroscopes.

Hydraulic induced fracturing (HIF) in oil wells is used to increase oil productivity by making the subterranean terrain more deep and permeable. In some cases HIF connects multiple oil pockets to the main well. Currently there is a need to understand and control with a high degree of precision the geometry, direction, and the physical properties of fractures. By knowing these characteristics (the specifications of fractures), other drill well locations and set-ups of wells can be designed to increase the probability of connection of the oil pockets to main well(s), thus, increasing productivity. The current state of the art of HIF characterization does not meet the requirements of the oil industry. In Mexico, the SENER-CONACyT funding program recently supported a three party collaborative effort between the Mexican Petroleum Institute, Schlumberger Dowell Mexico, and the Autonomous University of Juarez to develop a sensing scheme to measure physical parameters of a HIF like, but not limited to pressure, temperature, density and viscosity. We present in this paper a review of HIF process, its challenges and the progress of sensing development for down hole measurement parameters of wells for the Chicontepec region of Mexico.

MicroElectroMechanical Systems (MEMS) have become commercially successful in a number of niche applications. However, commercial success has only been possible where design, operating conditions, and materials result in devices that are not very sensitive to tribological effects. The use of MEMS in defense and national security applications will typically involve more challenging environments, with higher reliability and more complex functionality than required of commercial applications. This in turn will necessitate solutions to the challenges that have plagued MEMS since their inception - namely, adhesion, friction and wear. Adhesion during fabrication and immediately post-release has largely been resolved using hydrophobic coatings, but these coatings are not mechanically durable and do not inhibit surface degradation during extended operation. Tribological challenges in MEMS and approaches to mitigate the effects of adhesion, friction and wear are discussed. A new concept for lubrication of silicon MEMS using gas phase species is introduced. This "vapor phase lubrication" process has resulted in remarkable operating life of devices that rely on mechanical contact. VPL is also an effective lubrication approach for materials other than silicon, where traditional lubrication approaches are not feasible. The current status and remaining challenges for maturation of VPL are highlighted.

Medicine is clearly becoming one of the major challenges in the field of Applied Physics. The development of novel pharmaceutical devices, such as diagnostics, drug carriers or vaccines is growingly dependant on nanotechnology processes. Nanotechnology and MicroElectroMechanical Systems (MEMS) applied to biological issues have given rise to unprecedented biomimetic designs, which are leading the development of innovative tools, including high-throughput platforms for combinatorial bioassays, or microfluidics-based systems for the detection of diseases. This talk will address the use of MEMS and nanotechnology as a powerful combination for improving Public Health items, specifically through novel diagnostic systems for a wide set of human diseases. Also, we herein present our work involving the use of this approach for the development of a point-of-care test to detect tuberculosis, an infectious disease caused by Mycobacterium tuberculosis, one of the most evasive germs considered as potential biological warfare agents.

High performance thermoelectric materials in a wide range of temperatures are essential to broaden the application spectrum of thermoelectric devices. This paper presents experiments on the power and efficiency characteristics of lowand mid-temperature thermoelectric materials. We show that as long as an appreciable temperature difference can be created over a short thermoelectric leg, good power output can be achieved. For a mid-temperature n-type doped skutterudite material an efficiency of over 11% at a temperature difference of 600 °C could be achieved. Besides the improvement of thermoelectric materials, device optimization is a crucial factor for efficient heat-to-electric power conversion and one of the key challenges is how to create a large temperature across a thermoelectric generator especially in the case of a dilute incident heat flux. For the solar application of thermoelectrics we investigated the concept of large thermal heat flux concentration to optimize the operating temperature for highest solar thermoelectric generator efficiency. A solar-to-electric power conversion efficiency of ~5% could be demonstrated. Solar thermoelectric generators with a large thermal concentration which minimizes the amount of thermoelectric nanostrucutured bulk material shows great potential to enable cost-effective electrical power generation from the sun.

This paper presents our recent results on carbon nanomaterials for applications in energy storage and bio-sensor. More specifically: (i) A novel binder-free carbon nanotubes (CNTs) structure as anode in Li-ion batteries. The interfacecontrolled CNT structure, synthesized through a two-step chemical vapor deposition (CVD) and directly grown on copper current collector, showed very high specific capacity - almost three times as that of graphite, excellent rate capability. (ii) A large scale graphene film was grown on Cu foil by thermal chemical vapor deposition and transferred to various substrates including PET, glass and silicon by using hot press lamination and etching process. The graphene/PET film shows high quality, flexible transparent conductive structure with unique electrical-mechanical properties; ~88.80 % light transmittance and ~ 100 Ω/sq sheet resistance. We demonstrate application of graphene/PET film as flexible and transparent electrode for field emission displays. (iii) Application of individual carbon nanotube as nanoelectrode for high sensitivity electrochemical sensor and device miniaturization. An individual CNT is split into a pair of nanoelectrodes with a gap between them. Single molecular-level detection of DNA hybridization was studied. Hybridization of the probe with its complementary strand results in an appreciable change in the electrical output signal.

Two technologies for MEMS (Microelectromechanical Systems) scale cell formation are discussed. First, the fabrication of planar alkaline cell batteries compatible with MEMS scale power storage applications is shown. Both mm scale and sub-mm scale individual cells and batteries have been constructed. The chosen coplanar electrode geometry allows for easy fabrication of series connected cells enabling higher voltage while simplifying the cell sealing and electrode formation. The Zn/Ag alkaline system is used due to the large operating voltage, inherent charge capacity, long shelf life, and ease of fabrication. Several cells have been constructed using both plated and spun-on silver. The plated cells are shown to be limited in performance due to inadequate surface area and porosity; however, the cells made from spun-on colloidal silver show reasonable charge capacity and power performance with current densities of up to 200 uA/mm² and charge capacities of up to 18 mA-s/mm². Second, a new printing method for interdigitated 3-D cells is introduced. A microfluidic printhead capable of dispensing multiple materials at high resolution and aspect ratio is described and used to form fine interdigitated cell features which show >10 times improvement in energy density. Representative structures enabled by this method are modeled, and the energy and power density improvements are reported.

Flexible electronics require flexible energy storage, and electrochemical batteries are currently the strongest option for such devices. We further our previous investigation, beginning to add quantitative analysis to the composite mechanical/electrochemical performance of printed electrodes. The presented work will explain the principles of microfluidic stress analysis and how it provides insight into the operating conditions of real microbatteries.

Building battery architectures with functional interfaces that are interpenetrated in three dimensions opens the door to major gains in performance as compared to conventional 2-D battery designs, particularly with respect to the battery footprint. We are developing 3-D solid-state Li-ion batteries that are sequentially assembled from interpenetrating and tricontinuous networks of anode, cathode, and electrolyte/separator materials. We use fiberpaper- supported carbon nanofoams as a massively parallel, conductive, ultraporous base platform within which to create the 3-D cell. The components required for battery operation are incorporated into the x,y,z-scalable papers and include nanoscale coatings of metal oxides that serve as Li-ion-insertion electrodes and ultrathin, electroninsulating/ Li-ion conducting polymer coatings that serve as the electrolyte/separator.

Compound semiconductors offer significant advantages over silicon in photovoltaics due to their direct bandgaps, ability to form multijunction solar cells, as well as superior radiation hardness. However, costs for growth and integration of these materials have been prohibitively high, thereby limiting their large-scale implementation in terrestrial photovoltaics. Here we review materials growth and fabrication strategies that were recently developed to address many of these challenges by employing device-quality, multilayer epitaxial assemblies of compound semiconductors in the manner that enables sequential release of respective functional layers as well as reuse of the growth substrate. This new approach combined with techniques of micro-transfer printing provides a practical and cost-effective route to implement high quality compound semiconductors in terrestrial photovoltaics but also opens up new application possibilities and modes of use that have not been possible with conventional technologies.

This paper was presented at the SPIE conference indicated above but was submitted to the conference proceedings in error by M.C. McAlpine. The paper has been withdrawn from the SPIE Proceedings at the author’s request.

Nanotechnology - the science and engineering of manipulating matter at the molecular scale to create devices with novel chemical, physical and biological properties - has the potential to radically change oncology. Research sponsored by the NCI Alliance for Nanotechnology in Cancer has led to the development of nanomaterials as platforms of increasing complexity and devices of superior sensitivity, speed and multiplexing capability. Input from clinicians has guided researchers in the design of technologies to address specific needs in the areas of cancer therapy and therapeutic monitoring, in vivo imaging, and in vitro diagnostics. The promising output from the Alliance has led to many new companies being founded to commercialize their nanomedical product line. Furthermore, several of these technologies, which are discussed in this paper, have advanced to clinically testing.

Metallic nanoparticles are playing increasingly important roles in biodiagnostic platforms. This emergence reflects the need to detect disease indicating entities at increasingly lower levels in human and veterinary diagnostics, homeland security, and food and water safety. To establish this perspective, this paper overviews our recent work using surface enhanced Raman scattering for detection of proteins, viruses, and microorganisms in heterogeneous immunoassays. It describes the assay platform, which is comprised of an antibody-modified capture substrate and gold nanoparticle-based label. The latter draws on the ability to reproducibly construct gold nanoparticles modified with a monolayer of an intrinsically strong Raman scatterer that is then coated with a layer of antibodies. This construct, referred to as an extrinsic Raman label, takes advantage of the signal enhancement of scatterers when coated on nanometer-sized gold particles and the antigenic binding specificity of the immobilized antibody layer. Challenges related to nonspecific adsorption, particle stability, and measurement reproducibility are also briefly examined.

The goal of our project is to develop a unique ligand-conjugated nanoparticle (NP) therapy against childhood acute lymphoblastic leukemia (ALL). LLP2A, discovered by Dr. Kit Lam, is a high-affinity and high-specificity peptidomimetic ligand against an activated α4β1 integrin. Our study using 11 fresh primary ALL samples (10 precursor B ALL and 1 T ALL) showed that childhood ALL cells expressed activated α4β1 integrin and bound to LLP2A. Normal hematopoietic cells such as activated lymphocytes and monocytes expressed activated α4β1 integrin; however, normal hematopoietic stem cells showed low expression of α4β1 integrin. Therefore, we believe that LLP2A can be used as a targeted therapy for childhood ALL. The Lam lab has developed novel telodendrimer-based nanoparticles (NPs) which can carry drugs efficiently. We have also developed a human leukemia mouse model using immunodeficient NOD/SCID/IL2Rγ null mice engrafted with primary childhood ALL cells from our patients. LLP2A-conjugated NPs will be evaluated both in vitro and in vivo using primary leukemia cells and this mouse model. NPs will be loaded first with DiD near infra-red dye, and then with the chemotherapeutic agents daunorubicin or vincristine. Both drugs are mainstays of current chemotherapy for childhood ALL. Targeting properties of LLP2A-conjugated NPs will be evaluated by fluorescent microscopy, flow cytometry, MTS assay, and mouse survival after treatment. We expect that LLP2A-conjugated NPs will be preferentially delivered and endocytosed to leukemia cells as an effective targeted therapy.

Monolithic columns offer advantages as solid-phase extractors because they offer high surface area that can be tailored to a specific function, fast mass transport, and ease of fabrication. Porous glycidyl methacrylate-ethylene glycol dimethacrylate monoliths were polymerized in-situ in microfluidic devices, without pre-treatment of the poly(methyl methacrylate) channel surface. Cyclohexanol, 1-dodecanol and Tween 20 were used to control the pore size of the monoliths. The epoxy groups on the monolith surface can be utilized to immobilize target-specific probes such as antibodies, aptamers, or DNA for biomarker detection. Microfluidic devices integrated with solid-phase extractors should be useful for point-of-care diagnostics in detecting specific biomarkers from complex biological fluids.

Genomic analysis of biomarkers, including genetic markers such as point mutations and epigenetic markers such as DNA methylation, has become a central theme in modern disease diagnosis and prognosis. Recently there is an increasing interest in using single-molecule detection (SMD) for genomic detection. The driving force not only comes from its ultrahigh sensitivity that can allow the detection of low-abundance nucleic acids with reduced or without the need of amplification but also from its potential in achieving high-accuracy quantification of rare targets via singlemolecule sorting. The unique photophysical properties of semiconductor quantum dots (QDs) have made them ideal for use as spectral labels and luminescent probes. QDs also make excellent donors to pair with organic dyes in the fluorescence resonance energy transfer (FRET) process due to the features of narrow emission spectra and small Stokes shift. We have developed highly sensitive, quantitative and clinically relevant technologies for analysis of genomic markers based on the convergence of SMD, microfluidic manipulations, and quantum dot fluorescence resonance energy transfer technology (QD-FRET). Extraordinary performances of these new technologies have been exemplified by analysis of a variety of biomarkers including point mutations, DNA integrity and DNA methylation in clinical samples.

Carbon nanostructures such as carbon nanotubes (CNTs) and graphene are being applied to a wide variety of sensor applications. Both CNTs and graphene can be grown by chemical vapor deposition (CVD) from hydrocarbons using catalysts. Both materials require metallic catalysts. CNTs require small particles while graphene requires continuous films. Both materials can be grown by the thermal decomposition of SiC. Under the proper conditions either vertically aligned CNT arrays or planar graphene can be grown. Carbon source molecular beam epitaxy (CMBE) is also under development for growth of graphene. Like SiC decomposition, CMBE is catalyst free but it is not restricted to SiC substrates.

This paper gives a brief overview of the micro- and nano-electronic technologies for space applications under harsh environments, i.e. for operating temperatures beyond the range of -55°C to 125°C, and with exposure to radiation, pressure, shock, etc. The paper also addresses the technology reliability, the challenges and the qualification approaches for the harsh environment applications with a case study. The case study highlights the design-for-reliability approach and space qualification methodology developed to successfully design, fabricate, qualify, and infuse a motor drive electronics assembly with micro- and nano-electronics and packaging technology into a flight mission, which requires an operational temperature range over -128°C to +85°C.

Electrical detection of solution pH, protein adsorption and specific biomolecules were demonstrated by using graphene field-effect transistors (G-FETs). The monolayer graphene flakes were used as channel, which were obtained by conventional mechanical exfoliation from bulk graphite. The transport characteristics shifted to the positive voltage direction with increasing solution pH. The drain current changed by desorption of the charged protein. Moreover, we immobilized aptamers on the graphene surface. As a result, specific immunoglobulin sensing can be carried out using aptamer-modified G-FETs. These results strongly suggested that the G-FETs have high potentials for chemical and biological sensors.

We present a study of the effects of electron-beam irradiation on the Raman spectra and electronic transport properties of graphene and the operation of graphene field-effect transistors (GFET). Exposure to a 30 keV electronbeam causes negative shifts in the charge-neutral point (CNP) of the GFET, interpreted as due to n-doping in the graphene from the interaction of the energetic electron beam with the substrate. The electron beam is seen to also decrease the carrier mobilities and minimum conductivity of the graphene, as well as increase the intensity of the Raman D peak, all of which indicate defects generated in the graphene. We also study the relaxation of electronic properties after irradiation. The findings are valuable for understanding the effects of radiation damage on graphene and for the development of radiation-hard graphene-based electronics.

Realizing that no one sensing principle is perfect we set out to combine four fundamentally different sensing principles into one device. The reasoning is that each sensor will complement the others and provide redundancy under various environmental conditions. As each sensor can be fabricated using microfabrication the inherent advantages associated with MEMS technologies such as low fabrication costs and small device size allows us to integrate the four sensors into one portable device at a low cost.

Zeolite-coated cantilevers provided with internal heating elements have been developed and used for the selective detection of nitroderivates, in particular o-nitrotoluene as an example of an explosive-related molecule. In particular, Co exchanged commercial BEA zeolites have been deployed of rectangular Si cantilevers by microdropping technique. In particular, two different strategies have been demonstrated to increase the zeolite modified cantilevers performance: the sensing coating and the operating temperature. As a result, o-nitrotoluene LOD values below 1 ppm are attained at room temperature conditions; whereas the interference of toluene at concentrations below 1000 ppm is completely suppressed by heating the cantilever.

In the present article, the platform known as the Photonic Nose is presented as a versatile sensing concept for analysis of both liquid and vapor phase samples. By use of photonic crystal structures known as Bragg stacks with Bragg diffraction peaks within visible wavelengths, sensing events can be easily monitored by use of a digital camera to register color changes resulting from infiltration of analytes. We demonstrate the discrimination between pure solvent atmospheres, bacteria headspace as well as aqueous amine solutions as case examples of the variety of samples that can be analyzed with the platform.

I will describe recent developments of continuous wave, room temperature (CW/RT) high power QCLs at wavelengths < 3.8 μm to > 12 μm. QCLs now provide, on a commercial basis, CW/RT power of over 3 W at 4.6 μm, with a wall plug efficiency of over 15%, over 2 W at 4.0 μm, and over 1.2 W at 7.1 μm, with a wallplug efficiency >8%. I will describe insertion of QCLs into applications including MWIR countermeasures (IRCM), MWIR and LWIR target illuminators and designators, MWIR beacons (IFF), test equipment for measuring the efficacy of IRCM and sources for MWIR and LWIR radiation for detection of chemical warfare agents and explosives.

Micro- and nano-technologies (MNT) have opened up the mid-infrared (IR) spectral region to room temperature techniques that are enabling new applications in chemical imaging. The mid-IR is rich in wavelength specific absorptions that can be used to identify different chemicals and materials. It is only in the last decade, however, that mid- IR cameras and tunable, intense mid-IR laser sources have become available that are compact and operate at room temperature. MNT has allowed these developments; micro-bolometer arrays are now routinely fabricated with 25 μm resolution and the ability to sense mid-IR radiation from 7 to 14 um. Quantum cascade (QC) lasers fabricated with exquisite control of semiconductor layers and waveguides serve as the gain media for tunable mid-IR lasers, some even tuned with MEMS feedback elements. The current state of mid-IR imaging and illumination is discussed, and specific examples of its use in chemical imaging are presented. First, passive mid-IR imaging is considered, along with its ability to be used for chemical identification. The use of tunable mid-IR lasers as an illumination source is then considered. Technical aspects of illumination and detection paradigms are presented, with a consideration of how spectroscopic information gathered in both stimulated thermal emission and reflectance modes can be analyzed to determine chemical composition in an image. Finally, specific examples of QC laser assisted chemical imaging are presented.

It is well known that ultra-short pulse is able to change physical state of condensed matter: to melt, to evaporate, to ionize. It is less known that ultra-short pulse is able to change optical state -transmittance, reflectivity and polarization characteristics. In the same time a fact that ultra-short pulse may not change observable electronic state of the media passed practically unnoticed. Combination of the effects most pronounced in semiconductors were bandgap amplifies it in highly non-linear way. Changes in optical state are induced on the time scale comparable with pulse dwell time, but these changes last on the scale comparable with recombination time and depend on bandgap structure. Therefore we are introducing the term - Ultrafast Bandgap Photonics. When ultra-fast laser induces non-linear absorption, then Ultrafast Bandgap Photonic effects may be observed if combination of pulse dwell time, energy per pulse and pulse repetition rate satisfy very specific requirement. Ultrafast bandgap photonics is an optical and electronic phenomenon that changes spectral reflectivity, and transmittance as well as polarization characteristics when electronic structure of matter changes. Ultrafast Bandgap Photonics depends on pulse characteristics and bandgap structure. Ultrafast Bandgap Photonic effects are reversible and may not change physical state of media. Applications of Ultra-fast bandgap photonics are control of semiconductor characteristics and material properties. That includes, but is not limited, optically induced superconductivity, remote sensing and counter-sensing of all kind, laser cooling, bandgap material characteristics management. In this paper we discuss some foundations of ultra-fast bandgap photonics.

Spectroscopy based standoff detection systems: Raman and FTIR have been tested for detection of threat chemicals, including highly energetic materials, homemade explosives, explosives formulations and high explosives mixtures. Other threat chemicals studied included toxic industrial compounds (TIC) and chemical agent simulants. Microorganisms and biological threat agent simulants have also been detected at standoff distances. Open Path FTIR has been used to detect vapors and chemicals deposited on metal surfaces at μg/cm² levels at distances as far as 30 m in active mode and 60 m in passive mode. In the case of Raman telescope, standoff distances for acetonitrile and ammonium nitrate were 140 m.

We review our previous work to develop an uncooled subMMW detector capable of achieving an NEΔT ~0.5K at 30Hz frame rate and describe our approach to develop a staring subMMW camera based on a 2D array of such detectors. Both predicted and measured results of performance metrics (responsivity, NEP, response time, spectral bandwidth, NEΔT) are presented. The measured performance agrees reasonably well with predictions and is consistent with attaining our NEΔT goal. Thus far, 1×4 detector arrays have been fabricated, and 1×8 focal plane arrays have been developed and tested. We briefly discuss our vision to achieve a128×128 detector array needed for a practical staring subMMW imager and describe the technology challenges needed to realize it.

Standoff detection of explosives residues on surfaces at few meters was made using optical technologies based on Raman scattering, Laser-Induced Breakdown Spectroscopy (LIBS) and passive standoff FTIR radiometry. By comparison, detection and analysis of nanogram samples of different explosives was made with a microscope system where Raman scattering from a micron-size single point illuminated crystal of explosive was observed. Results from standoff detection experiments using a telescope were compared to experiments using a microscope to find out important parameters leading to the detection. While detection and spectral identification of the micron-size explosive particles was possible with a microscope, standoff detection of these particles was very challenging due to undesired light reflected and produced by the background surface or light coming from other contaminants. Results illustrated the challenging approach of detecting at a standoff distance the presence of low amount of micron or submicron explosive particles.

Here we report on a standoff spectroscopic technique for identifying chemical residues on surfaces. A hand-held infrared camera was used in conjunction with a wavelength tunable mid-IR quantum cascade laser (QCL) to create hyperspectral image arrays of a target with an explosive residue on its surface. Spectral signatures of the explosive residue (RDX) were extracted from the hyperspectral image arrays and compared with a reference spectrum. Identification of RDX was achieved for residue concentrations of 20 μg per cm² at a distance of 1.5 m, and for 5 μg per cm² at a distance of 15 cm.

Many advances have been made recently in both solid-state and semiconductor based mid-wave infrared (MWIR) and long-wave infrared (LWIR) laser technologies, and there is an ever growing demand for these laser sources for Naval, DOD and homeland security applications. We will present various current and future programs and efforts at Naval Air Warfare Center Weapons Division (NAWCWD) on the development of high-power, broadly tunable MWIR/LWIR lasers for sensing applications.

The paper focuses on the utilization of nanopositioning and nanomeasuring machines as a three dimensional coordinate measuring machine by means of the international harmonized communication protocol Inspection plus plus for Dimensional Measurement Equipment (abbreviated I++DME). I++DME was designed 1999 to enable the interoperability of different measuring hardware, like coordinate measuring machines, form tester, camshaft or crankshaft measuring machines, with a priori unknown third party controlling and analyzing software. Our recent work was focused on the implementation of a modular, standard conform command interpreter server for the Inspection plus plus protocol. This communication protocol enables the application of I++DME compliant graphical controlling software, which is easy to operate and less error prone than the currently used textural programming via MathWorks MATLab. The function and architecture of the I++DME command interpreter is discussed and the principle of operation is demonstrated by means of an example controlling a nanopositioning and nanomeasuring machine with Hexagon Metrology's controlling and analyzing software QUINDOS 7 via the I++DME command interpreter server.

We demonstrate a cost-effective and robust route to fabricate large-area microchannel plate (MCP) detectors, which will open new potential in larger area MCP-based detector technologies. For the first time, using our newly developed process flow we have fabricated large area (8"x8") MCPs. We used atomic layer deposition (ALD), a powerful thin film deposition technique, to tailor the electrical resistance and secondary electron emission (SEE) properties of large area, low cost, borosilicate glass capillary arrays. The self limiting growth mechanism in ALD allows atomic level control over the thickness and composition of resistive and SEES layers that can be deposited conformally on high aspect ratio capillary glass arrays. We have developed several robust and reliable ALD processes for the resistive coatings and SEE layers to give us precise control over the resistance (10⁶-10¹⁰Ω) and SEE coefficient (up to 5). This novel approach allows the functionalization of microporous, insulating substrates to produce MCPs with high gain and low noise. These capabilities allow a separation of the substrate material properties from the amplification properties. Here we describe a complete process flow to produce large area MCPs.

Recently there have been tremendous interests about the single molecule translocation through the SiN nanopore array. For DNA translocation and characterization, SiN nanopore array is easy to fabricate with high energy electron beam exposure. It is well known that the metallic nanopore can provide the huge enhancement, 10⁶ fold increase of the electromagnetic field at the metallic nanopore due to "hot spot" effect. In addition, the fabricated plasmonic micro device provides huge photon transmission through the fabricated nanochannel. In this report, we microfabricated the plasmonic nanopore with ~ 10¹ nm on top of the micronsize pyramidal structure for translocation and optical characterization using conventional microfabrication process and electron beam heating. The reduced Au nanopore due to electron beam heating is found to provide the huge optical transmission resulted in the huge photonic pressure gradient between the free space and nanopore inside. The huge pressure gradient can be attributed to the resonance transmission between the fabricated V groove cavity and the nanosize waveguide formed during the metal deposition. This fabricated plasmonic nano-aperture device can be utilized as bio-molecule translocation and optical characterization.

ZnO nanorods (NRs) sensors utilizing hybrid or monolithic integration of the NRs on nanoscale or microscale interdigitated electrodes (IDEs) were fabricated and characterized. The IDEs with their finger electrode width ranging from 50 nm to 3 μm were formed on SiO₂/Si substrates by nanoimprint lithography or conventional photolithography and metallization techniques, whereas the ZnO NRs were grown by chemical synthesis method. The average diameter of the ZnO NRs is about 100 nm, and their length can be varied from 2 to 5 μm by controlling growth time. When sensing targets, such as molecules or nanoparticles, bind onto the ZnO NRs, the conductance between IDEs will change. As probing test, II-VI quantum dots (QDs) were attached on the ZnO NRs, and clear responses were obtained by measuring and comparing current-voltage (I-V) characteristic of the sensor before and after binding the QDs.

In this paper, we present simulation results pertaining to our broadband solid-state optically and electrically pumped THz source design. Our design consists of a thin layer of dielectric sandwiched between a nano-grating and a thin film, such as metal, semiconductor, or high electron mobility material. By passing a DC current through the lower layer, a THz emission will be radiated from the nano-grating. We demonstrate preliminary current injection effects on surface plasmons propagating on this device utilizing known analytical surface plasmon formulas and COMSOL Multiphysics finite element analysis software.

In this paper we designed a highly tunable laser with a corrugated metallic nano-grating. The design leverages the free electron laser design based on either the transit of an e-beam in the vicinity of a metallic grating or the transit of an ebeam through a periodic, transverse magnetic field produced by arranging magnets with alternating poles. Our design consists of a nano-film that is evaporated over a PMMA nano-grating. Current is injected into the nano-grating thin film. The electrons in the injected current experience an oscillating motion due to the corrugated grating structure. If the mean free path of the electrons within the nano-grating is long enough compared to the nano-grating spacing, the electron wave emits electromagnetic radiation. We developed the electromagnetic emission theory by solving Maxwell's equations for a current injected into a nano-wave grating, taking into consideration the electron mean free path. A corrugated nano-grating device with an area of 300 μm × 300 μm and a 30 nm grating spacing was fabricated.

Recently, scientists have been looking for novel materials to improve the performance of optoelectronic devices. Graphene opens up new possibilities for infrared (IR) sensing applications. With a zero-bandgap graphene, electron-hole pairs can be generated easily by low energy photons such as middle-wave infrared signal. We have used an electricfield- assisted method to manipulate graphene between metal microelectrodes successfully. When a graphene contacts with a metal, a built-in potential forms at the interface and it separates the electron-hole pairs that flow as photocurrents. Based on this principle, we demonstrated using the graphene-based devices for infrared detection under a zero-bias operation. We also tried to apply the devices with positive and negative bias voltages, and results indicated the flow of photocurrent is independent of the polarity of the bias voltages.

We describe a novel fabrication method for producing polymer, glass, and metal micro- and nano-particles whose diameters range from 200 microns to under 50 nanometers. This method relies on the Rayleigh capillary instability in a multi-material fiber. The fiber core is made of the target material and has size close to the desired particle diameter embedded in a sacrificial polymer matrix. The fiber temperature is elevated to reduce the core viscosity and the Rayleigh instability results in the breakup of the core into a periodic string of spherical particles.

A micro differential thermal analysis (DTA) system is used for detection of trace explosive particles. The DTA system consists of two silicon micro chips with integrated heaters and temperature sensors. One chip is used for reference and one for the measurement sample. The sensor is constructed as a small silicon nitride membrane incorporating heater elements and a temperature measurement resistor. In this manuscript the DTA system is described and tested by measuring calorimetric response of 3 different kinds of explosives (TNT, RDX and PETN). This project is carried out under the framework of the Xsense project at the Technical University of Denmark (DTU) which combines four independent sensing techniques, these micro DNT sensors will be included in handheld explosives detectors with applications in homeland security and landmine clearance.

Translocation of DNA through a silicon nanopore with an applied voltage bias causes the ionic current signal to spike sharply downward as molecules block the flow of ions through the pore. Proper processing of the sampled signal is paramount in obtaining accurate translocation kinetics from the negative peaks, but manual analysis is time-consuming. Here, an algorithm is reported that automates the process. It imports the signal from a tab-delimited text file, automatically zero-baselines, filters noise, detects negative peaks, and estimates each peak's start and end time. The imported signal is processed using a zero-overlap sampling window. Peaks are detected by comparison of the window's standard deviation to a threshold standard deviation in addition to a comparison against a peak magnitude threshold. Zero-baselining and noise removal is accomplished through calculation of the mean of non-peak window values. The start and end times of a peak are approximated by checking where the signal becomes positive on either side of the peak. The program then stores the magnitude, sample number, approximate start time, and approximate end time of each peak in a matrix. All these tasks are automatically done by the program, requiring only the following initial input from the user: window size, file path to sampled signal data file, standard deviation threshold, peak magnitude threshold, and sampling frequency of the sampled signal. Trials with signals from an 11-micron pore sampled at 100 kHz for 30 seconds yielded a high rate of successful peak detection with a magnitude threshold of 600, a standard deviation threshold of 1.25, and a window size of 100.

We demonstrate a novel fabrication approach for high-throughput fabrication of engineered infrared plasmonic nanorod antenna arrays with Nanostencil Lithography (NSL). NSL technique, relying on deposition of materials through a shadow mask, offers the flexibility and the resolution to fabricate radiatively engineer nanoantenna arrays for excitation of collective plasmonic resonances. Overlapping these collective plasmonic resonances with molecular specific absorption bands can enable ultrasensitive vibrational spectroscopy. First, nanorod antenna arrays fabricated using NSL are investigated using SEM and optical spectroscopy, and compared against the nanorods with the same dimensions fabricated using EBL. No irregularities on the periodicity or the physical dimensions are detected for NSL fabricated nanorods. We also confirmed that the antenna arrays fabricated by NSL shows high optical quality similar to EBL fabricated ones. Furthermore, we show nanostencils can be reused multiple times to fabricate selfsame structures with identical optical responses repeatedly and reliably. This capability is particularly useful when high-throughput replication of the optimized nanoparticle arrays is desired. In addition to its high-throughput capability, NSL permits fabrication of plasmonic devices on surfaces that are difficult to work with electron/ion beam techniques. Nanostencil lithography is a resist free process thus allows the transfer of the nanopatterns to any planar substrate whether it is conductive, insulating or magnetic. As proof of the versatility of the NSL technique, we show fabrication of plasmonic structures in variety of geometries. We also demonstrate that nanostencil lithography can be used to achieve functional plasmonic devices in a single fabrication step, on variety of substrates. We introduced NSL for fabrication of nanoplasmonic structures including antenna arrays on rigid surfaces such as silicon, CaF2 and glass. In conclusion, Nanostencil Lithography enables plasmonic substrates supporting spectrally narrow far-field resonances with enhanced near-field intensities which are very useful for vibrational spectroscopy. We believe this nanofabrication scheme, enabling the reusability of stencil and offering flexibility on the substrate choice and nano-pattern design could significantly enhance wide-use of plasmonics in sensing technologies.

Cathodo-luminescence spectroscopy is performed on silver and gold lamellar gratings of period 7.5 or 20 microns for a range of grating amplitudes from 0.1 to 4.6 microns. The overall emission spectrum consists of a 400 nm wide band centered at ~600 nm which depends little on the grating amplitude, metal, or e-beam energy. For the larger grating amplitudes the emission spectrum is periodically modulated as a function of wavelength. Both the strength of the emission envelop and the depth and phase of the modulation depend on grating orientation with respect to the light collection axis, the distance of the excitation spot from the grating, and the distance between the grating and the collection optics. The modulation can be explained as interference of surface emission from grating bars and grooves. The origin of the emission remains unclear, as mechanisms of electron collision with image charge, transition radiation, surface contamination, and inverse photo-electron effect all fail to explain the observed spectrum. This work is relevant to the interpretation of cathodoluminescence studies of surface plasmons on structured metals for nano-photonic applications.

The DoD Center for Chemical Sensors Development at the University of Puerto Rico-Mayagüez has worked in developing sensors for threat agents for over 8 years. Work has continued under the ALERT DHS Center of Excellence. The approaches for sensing have covered many types of threat chemicals and some types of biological simulants, including high energetic materials, homemade explosives, mixtures and formulations, chemical agents simulants, toxic industrial chemicals and spore forming microorganisms. Sensing in the far field has been based in vibrational spectroscopy: Raman and infrared. Near field detection has been mainly based on nanotechnology enabled sensing platforms for Surface Enhanced Raman Scattering. Initial use of colloidal suspensions of silver and gold nanospheres eventually evolved to metallic and metal oxide nanorods and to particle immobilization, including sample smearing on substrates and drop-on-demand thermal inkjet printing of nanoparticles. Chemical reduction of metal ions has been substituted by clean photonic physical reduction that leaves the nanoactive surface highly exposed and overcomes the physico-chemical problem of double electrical layers posed by colloidal suspensions of nanoparticles. New avenues have open wide research endeavors by using laser techniques to form nanoprisms and interference based metallic nano-images and micro-images. UV based metal reduction on top of metal oxides nanostructures promises to provide the selectivity and sensitivity expected for the last 30-40 years. Various applications and experimental setups will be discussed.

We describe a new class of plasmonic photonic (PPh) crystal structures integrated onto a MEMS platform for high temperature-intensity, high speed, and high efficiency narrow band emitting and signaling applications in the infrared. We exploit 2D organized metallo-dielectric surface structures^1,2 for angular and spectral control of reflection, absorption and emission, efficiently in the infrared, with little or no leakage into adjacent visible or near-infrared bands. The 2D PPh structures are built on a MEMS platform, for thermal isolation from the environment. Recent advances² in the design of the 2D PPh structures allows for tremendous performance enhancement: high temperature/high intensity operation close to 1000 C and high speed (200Hz with 50% modulation), opening new applications in spectroscopy, infrared imaging, and signaling. Demonstrated wafer-level vacuum sealing improves the wall plug efficiency dramatically allowing these devices to be portable, light and battery operated. One potential application for these light-weight, low-power consumption, low-cost IR emitters is signaling and marking in 3-5 or 8- 12 micron thermal bands.

In this paper, we investigated the design of a photonic-crystal based three-dimensional (3D) cloaking structure with low-cost and improved performance. The carpet cloaking structure with truly 3D geometry is designed at optical frequencies. Compared with microwave cloaks where materials with large anisotropy are needed, the designed 3D cloak can be constructed using isotropic dielectric materials with small material parameter variations, which makes it suitable for practical implementation. By applying two-layer phase mask based holographic lithography, the designed cloaking structures can be fabricated rapidly and at low-cost, which will pave the way towards the mass production of invisibility cloak.

This work showcases developments in growth and performance of nanowire (NW) based photodetectors. Specifically the ability to transition from single NW devices to device arrays will be discussed. We have demonstrated the growth of semiconducting nanowires (NWs) using the physical vapor transport (PVT) method. CdSe and ZnSe NWs were grown and showed promising optical properties, including high transparency and a high ratio of band edge/deep level defect emission in photoluminescence (PL) measurements. Metal-semiconductor-metal (MSM) structures were fabricated from an array of ZnSe NWs, which showed an average increase of 10x in photocurrent and up to 720x for an individual device.

Electrostatic MEMS switches have become prevalent because of low power consumption and ease of integration in micro-fabrication technology. The equations governing their dynamic response obtained by energy methods are nonlinear differential equations. Even the unit-step response of these devices requires numerical computation. Depending on the magnitude of the applied step voltage and the presence of dielectric in the actuator, the response could be recurring or non-recurring. Estimating the period time and the switching time in these cases proves to be hard because one has to solve the energy equation numerically which could be time consuming or difficult to converge if it is not posed properly. Elata et al. have developed excellent methods to obtain these times on a logarithmic scale of voltage more easily for the undamped case. This paper extends their work for the case when the bottom plate is covered with a dielectric layer. The stagnation time occurring before dynamic pull-in, and the switching time thereafter are first shown as nonlinear graphs with the dielectric permittivity as a parameter. They are also linearized on an exponential scale and made useful for quick look up and convenience of designers.

In this work, an array of dielectrophoretic curved microelectrodes patterned in a microfluidic channel and integrated with a multimode rib polymeric waveguide is demonstrated. The microfluidic channel is infiltrated with suspended silica (SiO₂) and tungsten trioxide (WO₃) nanoparticles. The optofluidic system is found to be sensitive and responds not only to the infiltration of nanoparticle suspensions in the microfluidic channel, but also to the magnitude and frequencies of dielectrophoretic forces applied on the nanoparticles. The nanoparticles can be uniformly concentrated or repelled from the region between the curved microelectrode tips forming either a dense stream of flowing nanoparticles or a region void of nanoparticles in the evanescent sensitive region of the polymeric waveguide. The concentration and repulsion of nanoparticles from this region creates a refractive index gradient in the upper cladding of the polymeric waveguide. These conditions made it possible for light to either remain guided or be scattered as a function of dielectrophoretic settings applied on the nanoparticles. The results demonstrate that we successfully developed a novel tuneable polymeric waveguide based on dielectrophoretic assembly of nanoparticles suspended in fluids.

Dielectrophoresis (DEP) utilizing a curved microelectrode pattern was developed and integrated with a Raman spectroscopy system. The electrodes were patterned on a Raman transparent quartz substrate, and integrated with a microfluidic channel in poly-dimethylsiloxane (PDMS). This integrated system can be efficiently used for the determination of suspended particles type and the direct mapping of their spatial concentrations. It will be demonstrated that the integration of Raman mapping with dielectrophoretically controlled WO₃ particles can be used for studying suspended particles in situ.