The Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) and the Army Research Laboratory (ARL) have initiated a joint advanced technology demonstration program entitled "Prognostics/Diagnostics for the Future Force (PDFF)" with a key objective of developing low or no power embedded sensor suites for harsh environmental monitoring. The most critical challenge of the program is to specify requirements for the embedded sensor suites which will perform on-board diagnostics, maintain a history of sensor data, and forecast weapon health. The authors are currently collaborating with the PDFF program managers and potential customers to quantify the requirements for remotely operated, micro/nano-technology-based sensors for a host of candidate weapon systems. After requirements are finalized, current micro/nanotechnology-based temperature, humidity, g-shock, vibration and chemical sensors for monitoring the out-gassing of weapons propellant, as well as hazardous gaseous species on the battlefield and in urban environments will be improved to meet the full requirements of the PDFF program. In this paper, performance requirements such as power consumption, reliability, maintainability, survivability, size, and cost, along with the associated technical challenges for micro/nanotechnology-based sensor systems operating in military environments, are discussed. In addition, laboratory results from the design and testing of a wireless sensor array, which was developed using a thin film of functionalized carbon nanotube materials, are presented. Conclusions from the research indicate that the detection of bio-hazardous materials is possible using passive and active wireless sensors based on monitoring the reflected phase from the sensor.

This paper suggests a design for a Film Bulk Acoustic Resonator (FBAR) which utilizes a secondary piezoelectric layer for purposes of tuning the FBAR's resonant frequency. Currently, many ceramic resonators have difficulties in on-chip integration, power handling and electrode fabrication. FBARs are not only simple to fabricate and capable of full integration with CMOS/RF IC circuitry, but are also compact and can achieve high frequencies (GHz) with high quality factors. It is widely accepted that piezoelectric actuators encounter a significant change in mechanical stiffness between their open-circuit and closed-circuit states. In addition, it has been previously shown that the resonant frequency of a multi-layer FBAR is a function of the acoustic impedances and, correspondingly, the acoustic velocities, of its respective layers. Since the effective modulus term of the acoustic velocity of an FBAR layer is dependent on both the mechanical properties and electromechanical coupling of its piezoelectric element, and since electromechanical coupling can be altered by means a previously investigated shunt capacitor tuning concept, the stiffness of the piezoelectric tuning layer can be adjusted to vary the resonant frequency of the FBAR. Since difficulties have existed in matching FBAR resonant frequencies to specified values or making the frequencies stable during temperature variations, an active tuning capability for FBARs could offer many possible improvements. This work describes the application of the shunt capacitor tuning to a FBAR resonator and looks at the effects that varying different FBAR parameters have on the frequency range and degree of tunability of the device.

The design and modeling of a passive radio frequency wireless identification system based on surface acoustic wave (SAW) devices is presented in this paper. This radio frequency identification (RFID) system is developed based on the response of the reflected phase from a SAW device which consists of two or more arrays of SAW IDTs and reflectors with different IDT-reflector spacing. Pulse modulated signals are transmitted from a remote reader system and their echoes are returned with different time delays due to the different IDT-reflector distances. Corresponding IF signals are generated in a mixer and their phase differences can be used as an ID tag. Using coupled-mode theory of SAW, the phase characteristic was examined. The effect of relative distance between the two reflector arrays is demonstrated. Since this passive sensor is coupled with a small planar antenna, it is well suited for applications that require passive and conformal sensors for identification and tracking.

Highly aligned multi-wall carbon nanotube arrays up to 4 mm tall were synthesized on Si wafers using a chemical vapor deposition process with water delivery. Based on the long nanotube arrays, several prototype smart materials were developed including a biosensor, electrochemical actuator, and nanotube probes. The biosensor was formed by casting epoxy into a nanotube array and polishing the ends of the nanotubes. This electrode produced a near ideal sigmoidal cyclic voltammogram. Nanotube electrodes were then used to form a label-free immunosensor based on electrochemical impedance spectroscopy. The nanotube array immunosensor has good sensitivity, but decreasing the array size and improving the biofunctionalization is expected to dramatically increase the reproducibility and sensitivity. The electrochemical actuator was formed by bonding an electrode to a 1mm square by 4 mm long as-grown nanotube array post. The nanotube array actuator operated up to 10 Hz in a 2 M NaCl solution. With a driving voltage of 2 volts, the actuator produced 0.15% strain. Finally, nanotube bundles are being welded to tungsten tips and put inside glass needles for use as probes for biosensors and electrophysiology applications. All the smart materials applications discussed are recent, and further development is expected to yield improved performance and commodity level practical devices.

Extensive research is underway to understand and exploit the interface between biological materials and integrated systems Today, "nanotechnology" can be defined as a group of emerging technologies in which the structure of matter is controlled at the nanometer scale, the scale of small numbers of atoms, to produce novel materials and devices having useful and unique properties. An ideal biological candidate for use in nanoscale devices is the microtubule, an essential component of the eukaryotic cytoskeleton, which, unlike most proteins, has been shown to be electrically conductive. Due to the presence of an intrinsic dipole in the protein polymer, RF reflectance spectroscopy was chosen as an interrogation method. RF reflectance spectroscopy measures the electrical response of a sample in response to sinusoidally alternating currents as a function of frequency By interrogating the protein electrically, we are able to detect the polymerization state of the system, track any associated conductivity changes, and monitor binding of microtubule-associated proteins. We demonstrate manipulation of the microtubule system through the use of low-frequency electric fields, and discuss implications for sensor development.

Investigation of nanorod based solar cells is being conducted towards developing alternative, lightweight, flexible devices for commercial applications. A lot of research has been done in the area of dye sensitized solar cells in particular, which is currently the most stable and efficient excitonic solar cell. Aligned ZnO nanorods, with their high carrier mobilities serve as the conduction pathways for the excitons. In this paper we present seed synthesis techniques to obtain uniform aligned ZnO nanorod arrays with good crystalline on transparent conducting substrates. Scanning electron microscope, transmission electron microscope and electron diffraction were performed for material characterization. A comparative study is given for these two methods.

Organic semiconductors, such as pentacene, are particularly interesting because of its potential for various applications including thin film transistors (TFTs), electronic papers, radio frequency identification cards (RFIDs), and sensors. In this paper, we review recent progress in organic electronics with emphasis on their applications for sensing devices, and investigate the morphologies of pentacene films deposited on SiO₂ and Si surfaces at different substrate temperatures. Scanning electron microcopy (SEM) micrographs from a nominally 50nm-thick pentacene film on SiO₂ indicate that the grain sizes of pentacene film increase with an increase in substrate temperature. In addition, the grain size on clean silicon grown at a substrate temperature of 100 degrees C is markedly larger that on SiO₂, ranging 10~20μm. Based on this morphological investigation on pentacene films, various types of organic sensors and devices with conjunction with interdigitated, gated and ungated structures are presented.

The objective of this study is to evaluate the effect of ultrasonication on bismuth telluride nanocrystals prepared by solvothermal method. In this study, a low dimensional nanocrystal of bismuth telluride (Bi₂Te₃) was synthesized by a solvothermal process in an autoclave at 180°C and 200 psi. During the solvothermal reaction, organic surfactants effectively prevented unwanted aggregation of nanocrystals in a selected solvent while controlling the shape of the nanocrystal. The atomic ratio of bismuth and tellurium was determined by energy dispersive spectroscopy (EDS). The cavitational energy created by the ultrasonic probe was varied by the ultrasonication process time, while power amplitude remained constant. The nanocrystal size and its size distribution were measured by field emission scanning electron microscopy (FESEM) and a dynamic light scattering system. When the ultrasonication time increased, the average size of bismuth telluride nanocrystal gradually increased due to the direct collision of nanocrystals. The polydispersity of the nanocrystals showed a minimum when the ultrasonication was applied for 5 min.

Hydrogen production and delivery is critical to successful fuel cell operation. One of the most common methods to produce hydrogen is via electrolysis of water. However over-potential losses at the electrodes results in poor efficiency and an increase in power consumption. In this study we carried out experiments of water electrolysis with novel single crystal Ruthenium nano-rod arrays as the device cathode. We show that the increased active area of the nanostructured electrode serves to reduce the operating current density of the electrolyzer causing the over-potential to show a corresponding decrease. In addition to the decreased over-potential, the power needed to produce one mole of hydrogen was also reduced for the nanostructured electrolyzer compared to an electrolyzer with planar electrodes.

A dielectrophoretic oil filter concept utilizing three-dimensional electrode geometries for electric and flow field shaping is introduced. Dielectrophoretic separation systems that incorporate planar microelectrodes cannot effectively filter large amounts of fluids because the dielectrophoretic force rapidly decays as the distance from the electrodes increases. 3D electrode designs for flow-through dielectrophoretic separation/concentration/filtration systems are advantageous because 1) The 3D electrodes extend the electric field within the fluid. 2) The electrodes can be designed so that the velocity field as well as the electric field is shaped for maximum efficiency. and 3) Filtration of particles that are too small to be physically filtered is possible. Three novel electrode designs that are not based on 2D electrode designs are introduced. Initial experimental results from particle count analysis that suggest that a reduction of up to 90% of particulate contaminants could be achieved are presented (It is important to note that the standard deviation was large due to the small number of particles within view and the uneven distribution of particles within the oil).

This work investigates both DC and pulse electroplating techniques for nickel. A nickel sulfamate electrolyte is utilized for nickel deposition over Cu/Ti coated silicon substrates. Stress levels and grain morphology are investigated and analyzed for the electroplated nickel deposit. A comparison is also made between the results obtained from DC and from long and short duration pulse electroplating techniques. Both compressive and tensile built-in stresses are observed in both DC and long duration pulse plated nickel while only compressive stresses are observed in short duration pulse plated nickel.

This paper deals with micro-patterning process of EAPap (Electro-Active Paper) for achieving biodegradable and flexible MEMS. EAPap has been known as an active material with an interesting actuation phenomenon of papers. Such active materials were made by depositing very thin electrodes on both sides of cellulose paper strip. When an electric field is applied to the paper strip, a large displacement was produced. This active material has merits in terms of large strain, low voltage, low power consumption, dryness, cheap and biodegradable nature. This material can be designed in such a way that its advantages can be optimized. With these advantages and possibility, this material is attractive for biodegradable and flexible MEMS. This paper reports a micro-patterning process on flexible EAPap material. Key issues in this biodegradable MEMS fabrication with EAPap are 1) the preparation of EAPap material for micro scale fabrication, 2) micro patterning possibility on EAPap and 3) functional capabilities of sensing and actuation. This paper will introduce a micro contact printing for the micro patterning process on the EAPap flexible membrane.

The miniaturization of devices and synthesis of new materials have a tremendous role in the development of powerful electronics as well as material based technologies in other areas but for the laws of quantum mechanics posing limitations besides the increasing cost and difficulties in manufacturing at such a small scale. The quest, therefore, for the alternative technologies have stimulated a surge of interest in nano-meter scale materials and devices in the recent years. Metallic nano wires are the most attractive materials because of their unique properties having myriad applications like interconnects for nano-electronics, magnetic devices, chemical and biosensors, where as the hollow tubules are equally considered to be candidate for more potent applications- both in physical as well as biosciences. Materials' processing for nano-structured devices is indispensable to their rational design. The technique, known as "Template Synthesis", using electrochemical/electro less deposition is one of the most important processes for manufacturing nano/micro structures, nano-composites and devices and is relatively inexpensive and simple. The technique involves in using membranes- ion crafted ones (popularly known as Particle Track-Etch Membranes or Nuclear Track Filters), alumite substrate membranes, besides other types of membranes as templates. The parameters viz., diameter as well as length i.e., the aspect ratio, shape and wall surface traits in these membranes are controllable. In the present work, a detailed review of this technique, synthesis of nano/micro materials including hybrid materials and devices like field-ion emitters, resonant tunneling diodes (RTDs) etc. will be presented including most of the results obtained in our laboratory.

This paper reports on device fabrication and applications using vertically aligned nanowires (VANW) grown on silicon and flexible polyimide substrates. For bio hazards sensing applications, a tin oxide thin film was coated on the surface of nanowires to utilize high surface area density of nanostructured platform. Device fabrication processes include current silicon technology including lithography, plasma enhanced chemical vapor deposition (PECVD), and sol-gel process. The crystalline structure and sensing characteristics of tin oxide after annealing process were investigated with X-ray diffraction (XRD) and resistance monitoring at different concentration of isopropyl alcohol at part per million (ppm) levels. In addition, gold nanowires grown on flexible polyimide substrates were demonstrated, which can be used for a wide variety of applications including biomedical, display, and communication devices based on flexibility and transparency.

Recent advances in nanotechnology have stimulated a renewed interest in multisite recording of electrical activity of network of neurons, particularly using nanobiomaterials. This paper presents the simulation of electrical response of neurons cultured on microelectrode arrays based on the electronic equivalent model using Cadence PSD 15.0. The results were compared with those previously published models such as Kupfmuller and Jenik's model, McGrogan's Neuron Model which are based on the Hodgkin and Huxley model. We have developed and equivalent circuit model using discrete passive components to simulate the electrical activity of the neurons. It is observed that present equivalent model gives more accurate results with short computation time.

This paper presents our study on the synthesis and properties of magnetic nanotubes and their potential in neuroscience applications. Magnetic nanotubes were prepared by solution filtration through a template followed by thermal annealing and reduction. SEM and TEM were performed to characterize the as-prepared materials. To explore the potential use of magnetic nanotubes in neuroscience applications, we cultured neurons on iron oxide nanotube mats, and tested the effects of magnetic nanotubes on the growth of neurons. Based on our preliminary result, three original approaches for investigating and modulating neuron activities using magnetic nanotubes are proposed. The progress in this area of investigation could help to find better treatment for diseases in nervous systems in the future.

RF MEMS switches provide a low-cost, high performance solution for many RF/microwave applications these switches will be important building blocks for designing phase shifters, switched filters reflector array antennas for military and commercial markets. In this paper, progress in characterizing of THALES capacitive MEMS devices under high RF power is presented. The design, fabrication and testing of capacitive RF MEMS switches for microwave/mm- wave applications on high-resistivity silicon substrate is presented. The switches tested demonstrated power handling capabilities of 2W (33 dBm) for continuous RF power. The reliability of these switches was tested at various power levels indicating that under continuous RF power. In addition a description of the power failures and their associated operating conditions is presented The PC-based test stations to cycle switches and measure lifetime under DC and RF loads have been developed. Best-case lifetimes of 5x10¹⁰ cycles have been achieved in several switches from different lots under 33 dbm RF power.

This work investigates the Thin Film Bulk Acoustic Resonator operating at low frequencies. This study aims to substitute quartz resonators in the 4-27 MHz band and to fabricate selective filter for frequencies lower than 1GHz with quality factor higher than 10000. In this paper, we present the design, fabrication and testing of two different types of resonators. It consists of aluminum nitride film (0.8 μm) sandwiched between two aluminum electrodes (0.2 μm each). The first resonator is made by clamped edge beam and the second one is a free-free beam construction anchored in the middle of the cantilever. A demonstrator was achieved and the resonators are manufactured on a silicon substrate; AlN and Al layers were deposited on silicon using standard cathode sputtering technique. The resonators operate in extensional mode and the thicknesses of each of the materials are lower than 1μm. ANSYS, a Finite Element Analysis, has been performed to simulate the static, modal and harmonic behaviour. The simulation has been used, on the one hand, to determine the thickness of each material so as to reach the desired frequency range, on the other hand, to compare theoretical and experimental frequency values. First resonant frequencies between 2 and 10MHz were measured for resonators with dimensions of 20-40μm wide and 200-1000μm long and were found close to theory. Quality factor under 10000 operating in air has been achieved. These results confirm that such an integrated solution will replace Quartz oscillators and/or Surface Acoustic Wave filters in very compact applications.

Flexible dipole rectenna devices appeared to be attractive for this study because of the adaptability on complex structures; possibility for higher power density features, and ability of coupling. In this paper, design concepts and results of various flexible dipole rectennas will be discussed including their efficiencies. Using the result, some applications of the system will also be addressed. A typical output of a flexible dipole rectenna array produced up to 70 VDC and 300 mA with a 200W amplifier. The irradiance of the microwave power is measured as 20 - 200 mW/cm² at the distance of 130 cm from the horn. In this research, a 4 x 5 flexible rectenna array was used for actuation of a propeller of MAV which is required approximately 3W as an input power. The design concept of various rectennas that depends on the requirements of input for propellers/actuators in a vehicle is discussed.

We developed SH (shear horizontal) surface acoustic wave (SAW) sensors for detection of the immobilization and hybrdization of DNA (deoxyribonucleic acid) on the gold coated delay line of transverse SAW devices. The experiments of DNA immobilization and hybridization were performed with 15-mer oligonucleotides (probe and complementary target DNA). The sensor consists of twin SAW delay line oscillators (sensing channel and reference channel) fabricated on 36° rotated Y-cut X-propagation LiTaO₃ piezoelectric single crystals. The relative change in the frequency of the two oscillators was monitored to detect the immobilization of probe DNA with thiol group on the Au coated delay line and the hybridization between target DNA and immobilized probe DNA in pH 7.4 PBS (phosphate buffered saline) solution. In our previous work, we reported the sensitivity of 1.26 ng/ml/Hz with 100 MHz SAW sensors. Sensitivity of the SAW sensor is in nonlinear proportion to the oscillation frequency of the SAW device. Significant improvement of the sensitivity of the SAW DNA sensor has been achieved by increasing the oscillation frequency to 200 MHz. The sensitivity was improved to as high as 135 pg/ml/Hz. We addressed many engineering problems required for the increase of the oscillation frequency such as electromagnetic noise isolation, mechanical vibration isolation, acoustic noise absorbing, and digital signal processing.

As a first step to develop a health monitoring system with active and embedded nondestructive evaluation devices for the machineries and structures, multi-functional SAW (surface acoustic wave) device was developed. A piezoelectric LiNbO3(x-y cut) materials were used as a SAW substrate on which IDT(20μm pitch) was produced by lithography. On the surface of a path of SAW between IDTs, environmentally active material films of shape memory Ti50Ni41Cu(at%) with non-linear hysteresis and superelastic Ti48Ni43Cu(at%) with linear deformation behavior were formed by magnetron-sputtering technique. In this study, these two kinds of shape memory alloys SMA) system were used to measure 1) loading level, 2) phase transformation and 3)stress-strain hysteresis under cyclic loading by utilizing their linearity and non-linearity deformation behaviors. Temperature and stress dependencies of SAW signal were also investigated in the non-sputtered film state. Signal amplitude and phase change of SAW were chosen to measure as the sensing parameters. As a result, temperature, stress level, phase transformation in SMA depending on temperature and mechanical damage accumulation could be measured by the proposed multi-functional SAW sensor. Moreover, the wireless SAW sensing system which has a unique feature of no supplying electric battery was constructed, and the same characteristic evaluation is confirmed in comparison with wired case.

This work presents manufacturing and testing of a closed-loop drug delivery system where drug release is achieved by an electrochemical actuation of an array of polymeric valves on a set of drug reservoirs. The valves are based on bi-layer structures made of polypyrrole/gold in the shape of a flap that is hinged on one side of a valve seat. Drugs stored in the underlying chambers are released by bending the bi-layer flaps back with a small applied bias. These polymeric valves simultaneously function as both drug release components and biological/chemical sensors responding to a specific biological or environmental stimulus. The sensors may send signals to the control module to realize closed-loop control of the drug release. In this study a glucose sensor has been integrated with the polymeric actuators through immobilization of glucose oxidase(GOx) within polypyrrole(PPy) valves. Sensitivities per unit area of the integrated glucose sensor have been measured and compared before and after the actuation of the sensor/actuator PPy/DBS/GOx film. Other sensing parameters such as linear range and response time were discussed as well. Using an array of these sensor/actuator cells, the amount of released drug, e.g. insulin, can be precisely controlled according to the surrounding glucose concentration detected by the glucose sensor. Activation of these reservoirs can be triggered either by the signal from the sensor, or by the signal from the operator. This approach also serves as the initial step to use the proposed system as an implantable drug delivery platform in the future.

The brain and the human nervous system are perhaps the most researched but least understood components of the human body. This is so because of the complex nature of its working and the high density of functions. The monitoring of neural signals could help one better understand the working of the brain and newer recording and monitoring methods have been developed ever since it was discovered that the brain communicates internally by means of electrical pulses. Neural signal communication is achieved by the production and propagation of small electrical signals produced by the nerve cells called neurons. Neuroelectronics is the field which deals with the interface between electronics or semiconductors to living neurons. This includes monitoring of electrical activity from the brain as well as the development of feedback devices for stimulation of parts of the brain for treatment of disorders. This paper reviews the basic principles of Neuroelectronics which are used to develop several applications ranging from diagnostic tools to brain-computer interfaces, neural stimulation and several others.

We fabricated an apparatus for manipulation and welding of fine metal objects using a probe. The apparatus is composed of a work probe of a tungsten alloy needle, stages, a DC power supply, and an observation system. The work probe is held vertically above a gold substrate placed on stages to control the relative position against the work probe. The DC power supply is equipped to apply voltage of 0-10kV between the work probe and the substrate. One application of the apparatus is to repair probe cards. Thousands of contact probes (needles) are mounted on the printed circuit board (PCB) in the probe card. The contact probes are mounted one by one by the hands. Recently, an array of the contact probe on the PCB is produced by the LIGA process in response to narrower semiconductor pitch length. The problem is that there are no methods to repair a wrong contact probe. Whole of the contact probes should be a waste owing to one wrong contact probe. We propose to replace a wrong contact probe with a good one using our apparatus. Experiments to remove a contact probe by the apparatus is carried out using the specimen of a mimic probe card, where a cantilever type contact probes are arranged with a pitch of 25 micrometers. Removal of the wrong contact probe is carried out by a non-contact discharge and a contact discharge using the apparatus. High voltage of about 1-2kV is applied after the work probe is moved to above the target contact probe for the non-contact discharge. While high voltage of about10kV is applied after the work probe is positioned in contact with the target contact probe for the contact discharge. The target contact probe is removed by both methods, though the neighboring contact probes are damaged. The latter method is hopeful for removal for repair of the probe card.

This paper describes the use of Metal Rubber^TM, which is an electrically-conductive, low modulus, highly-flexible, and optically transparent free-standing or conformal coating nanocomposite material that is fabricated via Electrostatic Self-Assembly (ESA), as a polymer MEMS sensor for actuator materials. ESA is an environmentally-friendly layer-by-layer fabrication technique in which Metal Rubber^TM can be tailor designed at the molecular level to function as a sensor and/or electrode for active polymer devices. With its controllable and tailorable properties (such as mechanical modulus [from less than 0.1 MPa to greater than 500 MPa], electrical conductivity, sensitivity to flex and strain (tension and compression), thickness, transmission, glass transition, and more), Metal Rubber^TM exhibits massive improvements over traditional stiff electrodes and sensors (with bulky/heavy wire components) that physically constrain the actuator device motion and thus limit productivity. Metal RubberTM shows exceptional potential for use as flexible sensors, electrodes, and interconnect components for many active polymer applications. One example of such is NanoSonic's Metal Rubber^TM-Polymer MEMS (MR^TM-PMEMS) nanocluster-based corrosion sensor for aircraft coatings that was developed for an Air Force SBIR program. MR^TM-PMEMS was tailored via ESA for use as an in-situ sensor of chemical modifications and the breakdown of surface coatings via micro-strain measurements.

Photonic crystals (PC) are artificially fabricated crystals with a periodicity in the dielectric function. These crystals have the novel ability to mold and control light in three dimensions by opening a frequency region (bandgap) in which light is forbidden to propagate. We demonstrate using a simulation model that a photonic crystal sensor attached to a composite substrate will experience a significant change in its bandgap profile when damage is induced in the composite substrate. The frequency response of the photonic crystal sensor is modeled using the finite difference time domain (FDTD) method. A damage metric using principles of fuzzy pattern recognition is developed to evaluate and quantify the change in the frequency response in relation to the induced damage. Results for different damage scenarios are examined and reported with significantly high success rate. Successful developments of photonic crystal sensors will allow damage identification at scales not attainable using current sensing technologies.

Multilayered optical filters have been formed using layer-by-layer self-assembly processes. Unlike conventional vapor deposition coating techniques, molecular-level self-assembly is an aqueous solution-based process that is performed at room temperature and pressure. This allows the incorporation of a wider range of possible materials, including polymers, oxide and other nanoclusters, and other molecules. We review the general filter deposition method and give generalized results for nominal substrate materials.

An attempt has been made to design a CMOS single-chip chemical detection system for integrating nanocantilevers with low power readout electronic circuits for the detection of traces (few molecules) of hydrocarbon-based gases in the environment. The design is divided into two following building blocks: nanocantilevers as chemical sensors and readout electronics. Carbon nanotubes (CNT)-based cantilevers have been chosen for high-sensitivity chemical sensing for on-chip integration with the interface electronics. An experimental technique is presented for the fabrication of CNT cantilever beams. Design of a readout interface electronics using a switched capacitor technique is presented in 0.5 μm n-well CMOS process for integrating CNT cantilever sensors.

Electronic packaging is traditionally defined as the back-end process that transforms bare integrated circuits (IC) into functional products. As the IC feature size decreases and the size of silicon wafer increases, the cost per IC is reduced and the performance is enhanced. The future IC chips will be larger in size, have more input/output terminals (I/Os), and require higher power. In addition to the advancements in IC technology, electronic packaging is also driven by the market requirements for low cost, small size, and multi-functional electronic products. In response to these requirements, packaging related areas such as design, packaging architectures, materials, processes, and manufacturing equipment are all changing rapidly. Wafer-level packaging (WLP) offers the benefits of low cost and smallest size for single chip packages, since the package is done at wafer level other than individual die. After packages reach the horizontal limit of dimensions, 3D stacking solution provides more efficient packages through expanding packages in the vertical dimension. Functional integration is achieved with 3D stacking architectures. System in package (SiP), one of the solutions to system integration, incorporates electronics, non-electronic devices such as optical devices, biological devices, micro-electro-mechanical systems (MEMS), etc, and interconnection in a single package, to form smart structures or microsystems. MEMS devices require specialized packaging to serve new market applications. This paper and presentation describe the technology requirements and challenges of these advancing packaging areas. The potential solutions and future trends are presented.

This paper reports on a new method for estimation and minimization of mechanical stress on MEMS sensor and actuator structures due to packaging processes based on flip chip technology. For studying mechanical stress a test chip with silicon diaphragms was fabricated. A network of piezo-resistive solid state resistors created by diffusion was used to measure the surface tension pattern between adjacent diaphragms. Finite element method simulation was used to calculate the stress profile and to determine the optimum positions for placing the resistive network.

Needle-like probe holds fine objects by adhesions without any holding devices. It can not pick up heavy and large objects, because the gravity rivals the adhesions. Referring to electrostatic chucks (ESCs), we fabricated two needle-like probes, of which adhesions are assisted by the electrostatic force, a monopole probe and a dipole probe. The former corresponds to monopolar ESCs and the latter corresponds to dipolar ESCs. By the assistant of an external electric power, both can pick up heavy and large objects. The monopole probe, which is a tungsten needle, can manipulate 40-80μm gold particles on a gold substrate as follows. The probe is lowered until it touches the particle. After 20-50V is applied between the probe and the substrate, the probe is pulled up. Then the particle is picked up with the probe. Once the particle is in the air, it stays at the tip of the probe even if the voltage is reduced to 0. For release of the particle, the probe is lowered until the particle touches the substrate and is pulled up without applying voltage. The dipole probe is made of two electrodes embedded in an epoxy resin. Different from the monopole probe, the dipole probe attract both conductive and dielectric objects over a gap. The probe jumps up a styrene particle of 3mm over the gap of 1mm by applying 2kV, and it jumps up a gold particle of 0.4mm over the gap of 0.5mm by applying 5kV. The release is possible only by turning the applying voltage off. As the gravity is greater than the adhesions, the objects adhered falls. The assistant electrostatic force of the monopole probe is Johnsen-Rahbek force same with the clamping force of monopolar ESCs, and that of the dipole probe is gradient force same with the clamping force of bipolar ESCs.

In this paper, we focus on improving the performance of the piezoelectric diaphragms of micropumps. A novel circular lightweight piezoelectric composite actuator (LIPCA) with a high level of displacement and output force has been developed for piezoelectrically actuated micropumps. The actuator was designed and fabricated with oxide-based piezoelectric material in combination with carbon/epoxy fabric and glass/epoxy fabric. We used numerical and experimental methods to analyze the characteristics of the actuator. In addition, we used the developed circular LIPCA in conjunction with polydimethylsiloxane (PDMS) material and PDMS molding techniques to design, model and fabricate a valveless micropump. We then used a circular LIPCA bonded to a thin layer of PDMS as an actuator diaphragm. The actuator diaphragm can provide a comparatively high level of displacement, about twice that of conventional piezoelectric diaphragms that are commonly used in micropumps. The displacement of the diaphragm, the flow rate and the backpressure of the micropump were evaluated and discussed. With water, the pump reaches a maximum flow rate of 1.3 ml/min and a maximum backpressure of 4.1 kPa. The test results confirm that the circular LIPCA is a promising candidate for micropump application and can be used as a substitute for a conventional piezoelectric actuator diaphragm.

In this paper we describe a novel Fe-PDMS composite that can be used to create magnetically actuated polymeric microstructures. The composite is formed by suspending <10μm iron (Fe) particles in polydimethylsiloxane (PDMS) at concentrations ranging from 25-75% by weight. Material properties and processing capabilities have been examined, and to demonstrate material's usefulness we have designed, fabricated, and tested two prototypical micropumps that utilize an Fe-PDMS actuator membrane.

Benzo-Triazole (BTA) is considered as an important bridging material that can connect an organic polymer to the metal electrode on silicon wafers as a part of the microelectronics fabrication technology. We report a detailed process of surface induced 3-D polymerization of BTA on the Cu electrode material which was measured with the Ultraviolet Photoemission Spectroscopy (UPS), X-ray Photoemission Spectroscopy (XPS), and Scanning Tunneling Microscope (STM). The electric utilization of shield and chain polymerization of BTA on Cu surface is contemplated in this study.

A method to fabricate the metallic closed cellular material has been developed. Powder particles of polymer coated with a nickel-phosphorus alloy layer using electro-less plating were pressed into pellets and sintered at high temperatures by a furnace and a spark plasma sintering (SPS) system. A metallic closed cellular material containing different materials from that of cell walls was then fabricated. The mechanical properties of this material were measured. The results of the compressive tests show that this material has the different stress-strain curves among the specimens that have different thickness of the cell walls and the sintering temperatures of the specimens affect the compressive strength of each specimen. Also, it seems that the results of the compressive tests show that this material has high-energy absorption and Young's modulus of this material depends on the thickness of the cell walls and the sintering temperature. These obtained results emphasize that this material can be utilized as energy absorbing material and passive damping material.

The development of packaging for an underwater acoustic sensor is a more complex task than package design for a typical microelectronic device because of the need to simultaneously protect the device from the environment while allowing interaction with it. The goal of this work is to create an underwater acoustic sensor package that will allow sound transmission to the sensor while keeping out moisture and salt ions. A bio-inspired package, based on the hearing mechanisms in fish and other aquatic animals, has been developed for this purpose. The package will ensure reliability in the underwater environment while not interfering with the transmission of sound. The sensor design incorporates magnetostrictive iron-gallium (Galfenol) nanowires. Arrays of cilia-like nanowires mechanically respond to incoming sound waves, thus creating magnetic fields that are sensed by a GMR sensor. The package is designed to contain the nanowires in a fluid medium, leaving them free to move. Materials matching the acoustic impedance of seawater are incorporated to allow sound to penetrate the package. Acoustic properties of various materials were investigated using scanning acoustic microscopy for this application. A fabrication process for the package is presented. The fabrication incorporates a room temperature soldering process that will not harm the sensor during the bonding of package components.

Improved measurement of neural signals is needed for research into Alzheimer's, Parkinson's, epilepsy, strokes, and spinal cord injuries. At the heart of such instruments are microelectrodes that measure electrical signals in the body. Such electrodes must be small, stable, biocompatible, and robust. However, it is also important that they be easily implanted without causing substantial damage to surrounding tissue. Tissue damage can lead to the generation of immune responses that can interfere with the electrical measurement, preventing long-term recording. Recent advances in microfabrication and nanotechnology afford the opportunity to dramatically reduce the physical dimensions of recording electrodes, thereby minimizing insertion damage. However, one potential cause for concern is the reliability of the insulating coatings, applied to these ultra-fine-diameter wires to precisely control impedance. Such coatings are often polymeric and are applied everywhere but the sharpened tips of the wires, resulting in nominal impedances between 0.5 MOhms and 2.0 MOhms. However, during operation, the polymer degrades, changing the exposed area and the impedance. In this work, ultra-thin ceramic coatings were deposited as an alternative to polymer coatings. Processing conditions were varied to determine the effect of microstructure on measurement stability during two-electrode measurements in a standard buffer solution. Coatings were applied to seven different metals to determine any differences in performance due to the surface characteristics of the underlying wire. Sintering temperature and wire type had significant effects on coating degradation. Dielectric breakdown was also observed at relatively low voltages, indicating that test conditions must be carefully controlled to maximize reliability.

As MEMS find application niches in an increasingly wider range of systems and platforms, nonstandard methods of device excitation are being explored as a means to achieve the desired sensor or actuator functionality. One such nonstandard method, chaotic excitation, has been used as a research tool to understand nonlinear behavior in microsystems. An extension of this work involves the use of chaotic excitation and other nonlinear phenomena to provide detailed device state information, and to enhance device operation. In order to fully understand how a MEMS device will behave under chaotic excitation, a Veeco Instruments Wyko NT1100 optical profilometer with dynamic MEMS (DMEMS) measurement capability has been used to observe the motion of a chaotically excited lateral comb resonator (LCR) device. This briefing presents theoretical modeling results based on measured parameter values that are validated by experimentally measured chaotic displacement data. Methods of using this chaotic output data for pre-packaging and in situ MEMS fault detection are discussed. The application of chaotic driving schemes to improve the sensitivity of MEMS-based inertial and chemical sensors is briefly discussed as well.

In recent years micro-electro-mechanical system (MEMS) sensors have drawn considerable attention due to their attraction in terms of miniaturization, batch fabrication and ease of integration with the required electronics circuitry. Micro-opto-electro-mechanical (MOEM) devices and systems, based on the principles of integrated optics and micromachining technology on silicon have immense potential for sensor applications. Employing optical techniques have important advantages such as functionality, large bandwidth and higher sensitivity. Pressure sensing is currently the most lucrative market for solid-state micro sensors. Pressure sensing using micromachined structures utilize the changes induced in either the resistive or capacitive properties of the electro-mechanical structure by the impressed pressure. Integrated optical pressure sensors can utilize the changes to the amplitude, phase, refractive index profile, optical path length, or polarization of the lightwave by the external pressure. In this paper we compare the performance characteristics of three types of MOEM pressure sensors based on Mach-Zehnder Interferometer (MZI), Directional Coupler (DC) and racetrack resonator (RR) integrated optical geometries. The first two configurations measure the pressure changes through a change in optical intensity while the third one measures the same in terms of frequency or wavelength change. The analysis of each sensors has been carried out in terms of mechanical and optical models and their interrelationship through optomechanical coupling. For a typical diaphragm of size 2mm × 1mm × 20 μm, normalized pressure sensitivity of 18.35 μW/mW/kPa, 29.37 μW/mW/kPa and 2.26 pm/kPa in case of MZI, DC and RR devices have been obtained respectively. The noise performance of these devices are also presented.

In this paper the dynamics of MEMS devices is explored, which characterizes the behavior of a thermally-actuated MEMS in order to perform a system identification enabling controlled operation of the micro-device. By considering the input to the system is the current/voltage and the output is the amplified mechanical displacement, a transfer function, TF, is derived which includes energy losses due to the imperfect energy conversion from electric to thermal, and which correspond to various phenomena, such as convection, radiation and conduction - accounting for a Joule-effect temperature less than the ideal one. This TF also includes the relationship between temperature and the mechanical deformation of both "active and passive" flexure hinges, which are thermally-actuated and which contribute to the kinematics of the output motion of the micro-device. This TF model is validated by means of experimental data from an actual displacement-amplification MEMS which was fabricated by means of the PolyMUMPs surface machining technology.

Missiles, rockets and certain types of industrial machinery are exposed extreme vibration environments, with high frequency/amplitude mechanical vibrations which may be detrimental to components that are sensitive to these high frequency mechanical vibrations, such as MEMS gyroscopes and resonators, oscillators and some micro optics. Exposure to high frequency mechanical vibrations can lead to a variety of problems, from reduced sensitivity and an increased noise floor to the outright mechanical failure of the device. One approach to mitigate such effects is to package the sensitive device on a micromachined vibration isolator tuned to the frequency range of concern. In this regard, passive micromachined silicon lowpass filter structures (spring-mass-damper) have been developed and demonstrated. However, low damping (especially if operated in near-vacuum environments) and a lack of tunability after fabrication has limited the effectiveness and general applicability of such systems. Through the integration of a electrostatic actuator, a relative velocity sensor and the passive filter structure, an active micromachined mechanical lowpass vibration isolation filter can be realized where the damping and resonant frequency can be tuned. This paper presents the development and validation of a key component of the micromachined active filter, a sensor for measuring the relative velocity between micromachined structures.

A new power concept has been contemplated for High Altitude Airship (HAA) under the consideration of direct energy conversion cycles, such as photovoltaic (PV) cells and advanced thermoelectric (ATE) generator. The HAA has various potential applications and mission scenarios that require onboard energy harvesting and power distribution systems. Both PV cells and an ATE system were briefly compared to identify the advantages of ATE for HAA applications in this study. Utilizing the estimated high efficiency of a threestaged ATE in a tandem mode, the ATE generates a higher quantity of harvested energy than PV cells for mission scenarios. The ATE's performance figure of merit of 5 was considered to estimate the cascaded efficiency of a three-staged ATE system. The estimated efficiency of a tandem system appears to be greater than 60%. Based on this estimated efficiency, the configuration of a HAA and the power utility modules are defined. Conventional photovoltaic cells have been used for NASA's long duration airplanes, the solar-powered Pathfinder, and remotely piloted aircraft [1]. However, the cost and weight of high efficiency photovoltaic cells pose a shortcoming for wide and unlimited applications. Among others is the fuel cell, but it is a fuel-carrying power generation system. A conceptual study for the HAA power budget plan has been done at NASA Langley Research Center by utilizing new nanomaterials for solar power harvesting.

Microelectromechanical System (MEMS) switches offer outstanding performance over wide bandwidth, minimum weight, sue, and power consumption, and significantly improved reliability unmatched by any other electronic switches deploying GaAS FETs or GaAs PIN-diodes or GaAs HEMTs. These switches are best suited for applications that require high signal purity in terms of signal linearity, insertion loss, isolation, and power consumption. RF-MEMS switches offer reliability exceeding ten billion life cycles and low insertion loss and high isolation while operating over uh-wideband. Design parameters and fabrication aspects of RF-MEMS shunt and series switches are investigated, which will permit switch operation over 60 to 94 GHz range.

This paper reports a Ka-band microstrip patch antenna fabricated using post-CMOS compatible process technology. The antenna uses an air cavity underneath the patch radiator that is supported on thin membrane. To start with, a thin dielectric film of silicon dioxide is deposited on <100> single crystal silicon substrates by RF sputtering process. The membrane is then realized using bulk micromachining technology. The antenna structure was analyzed and optimized using the finite-element method (FEM) based Ansoft High Frequency Structure Simulator software (version 9). The antenna structure mounted on a test jig with K-connector was used for testing its performance. The measured results of the fabricated prototype antenna agree quite closely with the simulated results. The fabricated antenna resonated at 36 GHz with -10 dB return loss bandwidth of 1.2 GHz. In the absence of access to well-established MEMS foundry, the RF sputtering process reported here can be advantageously used for rapid prototyping of many antenna structures.