This PDF file contains the front matter associated with SPIE Proceedings Volume 9802, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Missiles and weaponry-based systems are composed of metal structures that can degrade after prolonged exposure to environmental elements. A particular concern is accumulation of corrosion that generally results from prolonged environmental exposure. Corrosion, defined as the unintended destruction or deterioration of a material due to its interaction with the environment, can negatively affect both equipment and infrastructure. System readiness and safety can be reduced if corrosion is not detected, prevented and managed. The current corrosion recognition methods (Visual, Radiography, Ultrasonics, Eddy Current, and Thermography) are expensive and potentially unreliable. Visual perception is the most commonly used method for determining corrosion in metal. Utilization of an inductance-based sensor system is being proposed as part of the authors’ research. Results from this research will provide a more efficient, economical, and non-destructive sensing approach. Preliminary results demonstrate a highly linear degradation within a corrosive environment due to the increased surface area available on the sensor coupon. The inductance of the devices, which represents a volume property of the coupon, demonstrated sensitivity to corrosion levels. The proposed approach allows a direct mass-loss measurement based on the change in the inductance of the coupon when placed in an alternating magnetic field. Prototype devices have demonstrated highly predictable corrosion rates that are easily measured using low-power small electronic circuits and energy harvesting methods to interrogate the sensor. Preliminary testing demonstrates that the device concept is acceptable and future opportunities for use in low power embedded applications are achievable. Key results in this paper include the assessment of typical Army corrosion cost, degradation patterns of varying metal materials, and application of wireless sensors elements.

Graphene has been extensively investigated as a promising material for various types of high performance sensors due to its large surface-to-volume ratio, remarkably high carrier mobility, high carrier density, high thermal conductivity, extremely high mechanical strength and high signal-to-noise ratio. The power density and the corresponding die temperature can be tremendously high in scaled emerging technology designs, urging the on-chip sensing and controlling of the generated heat in nanometer dimensions. In this paper, we have explored the feasibility of a thin oxide graphene nanoribbon (GNR) as nanometer-size temperature sensor for detecting local on-chip temperature at scaled bias voltages of emerging technology. We have introduced an analytical model for GNR FET for 22nm technology node, which incorporates both thermionic emission of high-energy carriers and band-to-band-tunneling (BTBT) of carriers from drain to channel regions together with different scattering mechanisms due to intrinsic acoustic phonons and optical phonons and line-edge roughness in narrow GNRs. The temperature coefficient of resistivity (TCR) of GNR FET-based temperature sensor shows approximately an order of magnitude higher TCR than large-area graphene FET temperature sensor by accurately choosing of GNR width and bias condition for a temperature set point. At gate bias V_GS = 0.55 V, TCR maximizes at room temperature to 2.1×10⁻² /K, which is also independent of GNR width, allowing the design of width-free GNR FET for room temperature sensing applications.

Hybrid composites with organic and inorganic materials are drawing interest to researchers by adopting advantages of organic materials and inorganic materials. Cellulose is biocompatible, cheap, environmentally friendly, renewable and lightweight material. Nano crystalline form of cellulose (CNC) is a needle like rigid structure with a very high mechanical strength. Graphene, crystalline forms of carbon, provides basic platform for many electronic and optoelectronic devices. This paper introduces the fabrication process of cellulose nanocrystal/graphene oxide blended nanocomposite film. Cellulose nanocrystal/graphene oxide nanocomposite films are prepared by mixing graphene oxide (GO) into cellulose nanocrystal suspension using ultrasonic homogenizer. Scanning electron microscopy is used to study morphology. Optical properties of the composite was characterized to evaluate the change in transparency after addition of GO in CNC.

This paper provides a preliminary study on the piezoresistive effect of a styrene-butadiene Rubber (SBR), one of the main ingredients of automotive tire, dispersed with carbon nanotubes (CNTs) to explore its feasibility as a force sensor embedded in automotive tires. Typically, the application of CNTs has been successfully applied to the mechanical sensing technology such as a stress/strain and impact sensor. In this study, the potential of using the SBR/CNT as a force sensor for monitoring automotive tire deformation is evaluated for the first time. Experimental results show that the electrical resistance of the SBR/CNT composite changes in response to the sinusoidal loading, as well as static compressive load. These piezoresistive responses of the SBR/CNT composite will be used for sensing the tire deformation caused by the vehicle loading or cracks of tires.

In this paper, we have explored the feasibility of a metallic single-walled carbon nanotube (SWCNT) as a radiation detector. The effect of SWCNTs’ exposure to different ion irradiations is considered with the displacement damage dose (DDD) methodology. The analytical model of the irradiated resistance of metallic SWCNT has been developed and verified by the experimental data for increasing DDD from 10¹² MeV/g to 10¹⁷ MeV/g. It has been found that the resistance variation of SWCNT by increasing DDD can be significant depending on the length and diameter of SWCNT, such that the DDD as low as 10¹² (MeV/g) can be detected using the SWCNT with 1cm length and 5nm diameter. Increasing the length and diameter of SWCNT can result in both the higher radiation sensitivity of resistance and the extension of detection range to lower DDD.

Radioisotope thermoelectric generators (RTGs) running off the radioisotope Pu²³⁸ are the current standard in deep space probe power supplies. While reliable, these generators are very inefficient, operating at only ~7% efficiency. As an alternative, more efficient radioisotope thermionic emission generators (RTIGs) are being explored. Like RTGs, current RTIGs concepts use exotic materials for the emitter, limiting applicability to space and other niche applications. The high demand for long-lasting mobile power sources would be satisfied if RTIGs could be produced inexpensively. This work focuses on exposing several common materials, such as Al, stainless steel, W, Si, and Cu, to elevated temperatures under vacuum to determine the efficiency of each material as inexpensive replacements for thermoelectric materials.

Current best practice in epitaxial growth of rhombohedral SiGe onto (0001) sapphire (A_l2O₃) substrate surfaces requires extreme conditions to grow a single crystal SiGe film. Previous models described the sapphire surface reconstruction as the overriding factor in rhombohedral epitaxy, requiring a high temperature Al-terminated surface for high quality films. Temperatures in the 850-1100°C range were thought to be necessary to get SiGe to form coherent atomic matching between the (111) SiGe plane and the (0001) sapphire surface. Such fabrication conditions are difficult and uneconomical, hindering widespread application. This work proposes an alternative model that considers the bulk sapphire structure and determines how the SiGe film nucleates and grows. Accounting for thermal expansion effects, calculations using this new model show that both pure Ge and SiGe can form single crystal films in the 450-550°C temperature range. Experimental results confirm these predictions, where x-ray diffraction and atomic force microscopy show the films fabricated at low temperature rival the high temperature films in crystallographic and surface quality. Finally, an explanation is provided for why films of comparable high quality can be produced in either temperature range.

Nano-mechanical sensing exploiting frequency shift of a cantilever beam to obtain the mass of an object is well established. This paper is aimed at investigating the possibility of sensing mass as well as rotary inertia of an attached object. The rotary inertia of an object gives additional insight into its shape, which is a key motivation of this work. It is shown that by using two modes it is possible to formulate two coupled nonlinear equations, which it turn can be solved to obtain mass and rotary inertia simultaneously from the frequency shifts of first two vibration modes. Analytical results are validated using high fidelity molecular mechanics simulation.

Additive manufacturing or 3D printing techniques are being vigorously investigated as a replacement to the traditional and conventional methods in fabrication to bring forth cost and time effective approaches. Introduction of 3D printing has led to printing micro and nanoscale structures including tissues and organelles, bioelectric sensors and devices, artificial bones and transplants, microfluidic devices, batteries and various other biomaterials. Various microfabrication processes have been developed to fabricate micro components and assemblies at lab scale. 3D Fabrication processes that can accommodate the functional and geometrical requirements to realize complicated structures are becoming feasible through advances in additive manufacturing. This advancement could lead to simpler development mechanisms of novel components and devices exhibiting complex features. For instance, development of microstructure electrodes that can penetrate the epidermis of the skin to collect the bio potential signal may prove very effective than the electrodes that measure signal from the skin’s surface. The micro and nanostructures will have to possess extraordinary material and mechanical properties for its dexterity in the applications. A substantial amount of research being pursued on stretchable and flexible devices based on PDMA, textiles, and organic electronics. Despite the numerous advantages these substrates and techniques could solely offer, 3D printing enables a multi-dimensional approach towards finer and complex applications. This review emphasizes the use of 3D printing to fabricate micro and nanostructures for that can be applied for human healthcare.

In recent years, the fabrication of patient organ replicas using 3D printers has been attracting a great deal of attention in medical fields. However, the cost of these organ replicas is very high as it is necessary to employ very expensive 3D printers and printing materials. Here we present a new gel organ replica, of human kidney, fabricated with a conventional molding technique, using a particle-double network hydrogel (P-DN gel). The replica is transparent and has the feel of a real kidney. It is expected that gel organ replicas produced this way will be a useful tool for the education of trainee surgeons and clinical ultrasonography technologists. In addition to developing a gel organ replica, the internal structure of the P-DN gel used is also discussed. Because the P-DN gel has a complex structure comprised of two different types of network, it has not been possible to investigate them internally in detail. Gels have an inhomogeneous network structure. If it is able to get a more uniform structure, it is considered that this would lead to higher strength in the gel. In the present study we investigate the structure of P-DN gel, using the gel organ replica. We investigated the internal structure of P-DN gel using Scanning Microscopic Light Scattering (SMILS), a non-contacting and non-destructive.

Medical doctors use artificial blood vessels and organ models, which are usually made of plastic, to explain operations to students, or patients awaiting treatment. However, there are some problems such as the high cost of making the model and there is not a realistic feel because the model is hard. These problems can be solved using soft and wet material for instance gel. Gels are materials with unique properties such as transparency, biocompatibility, and low friction. In recent years, high strength gel has been developed and is expected to be applied in medical fields in the future. Artificial models of gel can be produced by 3D gel printers. Our group has been developing a 3D gel printer with 1mm precision in printing, but the shape, size and mechanical strength are not sufficient for medical models. In this study, we overcome these problems and make a gel model which is transparent, mechanically strong with a fine shape. The strength and molding accuracy is improved by changing and preparing the cross linker and ultraviolet absorber. We conducted mechanical and molding tests to confirm that the gel material properties improved.

In our group, highly transparent shape memory gels were successfully synthesized for the first time in the world. These gels have the high strength of 3MPs modulus even with the water content of 40wt% water and high transparency. We consider that these highly transparent and high strength gels can be applied to the optical devices such as intraocular-lenses and optical fibers. In previous research by our group, attempts were made to manufacture the gel intraocular-lenses using highly transparent shape memory gels. However, it was too difficult to print the intraocular-lens finely enough. Here, we focus on a 3D printer, which can produce objects of irregular shape. 3D printers generally we fused deposition modeling (FDM), a stereo lithography apparatus (SLA) and selective laser sintering (SLS). Because highly transparent shape memory gels are gelled by light irradiation, we used 3D printer with stereo lithography apparatus (SLA). In this study, we found the refractive index of highly transparent shape memory gels depend on monomer concentration, and does not depend on the cross-linker or initiator concentration. Furthermore, the cross-linker and initiator concentration can change the gelation progression rate. As a result, we have developed highly transparent shape memory gels, which can have a range of refractive indexes, and we defined the optimal conditions that can be modeling in the 3D printer by changing the cross-linker and initiator concentration. With these discoveries we were able to produce a gel intraocular-lens replica.

A 3D printer is a device which can directly produce objects whose shape is the same as the original 3D digital data. Hydrogels have unique properties such as high water content, low frictional properties, biocompatibility, material permeability and high transparency, which are rare in hard and dry materials. These superior characteristics of gels promise useful medical applications. We have been working on the development of a 3D gel printer, SWIM-ER (Soft and Wet Industrial – Easy Realizer), which can make models of organs and artificial blood vessels with gel material. However, 3D printing has a problem: the mechanical properties of the printed object vary depending on printing conditions, and this matter was investigated with SWIM-ER. In the past, we found that mechanical properties of 3D gel objects depend on the deposition orientation in SWIM-ER. In this study, gels were printed with different laser scanning speeds. The mechanical properties of these gels were investigated by compression tests, water content measurements and SMILS (Scanning Microscopic Light Scattering).

This paper presents the study of propagation of elastic waves in nanostructures using continuum approximation. The wave propagation characteristics in both 1-D and 2-D nanostructures, namely the carbon nanotubes and Graphene are studied in this paper. In particular, the use of various gradient elasticity theories, namely the Eringen’s Stress gradient theory, the second and fourth order strain gradient theories, that brings in atomistic length scale parameters into the continuum governing equations, is used in this paper to study the wave propagation characteristics in the nanostructures. Using these non-local theories, wave propagation in Single and Multi-wall carbon tubes and monolayer Graphene structures are studied. A number of examples are presented that brings out the essential wave propagation features such as escape frequency, cut-off frequencies, phase speeds and group speeds in these structures.

γ-PGA is a versatile multi-functional biopolymer possessing much useful biological functionality. Each biological function is associated with specific properties related to various forms of γ-PGA. However, to date, knowledge about the molecular mechanism to control specific structures of γ-PGA under a certain environmental conditions are unknown. In this study, we used single molecule force spectroscopy (SMFS) method to characterize the structure of γ-PGA in two environmental conditions. A water environment or 0.5 M MgCl₂ salt solution was used to observe the effect of metal ion on γ-PGA structure at room temperature. The obtained results revealed that γ-PGA exists branched and/or cross-linked structure of γ-PGA in water or MgCl₂ salt solution.

The class of fabricated materials known as metamaterials, with its promises for unconventional material properties or characteristics, has opened up a whole new paradigm of possibilities and challenges. The primary enablers have been capabilities at the very low length scale and novel design configurations. Pentamode metamaterials, having fluid like properties, is one such idea to have been realized in recent past. This type of fabricated materials show high bulk modulus but low shear modulus. The fundamental constituent element is a rod like structure tapered down on both ends. Four of such elements meet at any joint, two of which in a plane orthogonal to that of the other two. The dynamics and wave propagation characteristics of such structures have been studied with an aim to obtain band structures formed because of their periodic nature. Here, a methodology has been developed to compute the wave propagation characteristics of such pentamode structures using spectrally formulated finite elements based on frequency domain Ritz method. Bloch theory has also been used to represent the dynamics of an infinite structure through that of a unit cell. The proposed method is computationally more efficient compared to one using conventional finite element. A few variants of pentamodes are also analyzed to arrive at configurations with superior wave propagation characteristics.

In the last decade, several innovative polymer gel materials with enhanced mechanical proper ties have been invented by Japanese researches. In 2003, a most effective but simple way was proposed to synthesize double network gels, with compression fracture stress of about 30MPa, compared to several tens of kPa for common gels. In this study, we evaluate the wear of a double network gel, both with and without water lubrication. In the un-lubricated experiment, the gel surface is worn with a stainless steel ball. In the other experiment with water lubrication, the gel surface is worn by different counter surfaces because the stainless steel ball was too smooth to wear. It was found that frictional vibration of wear gel is transitioning to steady sliding in lubricated. As conventional reduction method of the friction by the contact between general solids, there are surface processing such as the texturing, attachment of lubrication materials. In the case of gel, the minute processing to the surface such as the texturing is difficult, because the gel is soft in comparison with the hard materials such as the metal. By proceeding with this study, the surface processing of low-frictional gels will be enabled.

Advances in the development of novel materials and fabrication processes are resulting in an increased number of flexible and stretchable electronics applications. This evolving technology enables new devices that are not readily fabricated using traditional silicon processes, and has the potential to transform many industries, including personalized healthcare, consumer electronics, and communication. Fabrication of stretchable devices is typically achieved through the use of stretchable polymer-based conductors, or more rigid conductors, such as metals, with patterned geometries that can accommodate stretching. Although the application space for stretchable electronics is extensive, the practicality of these devices can be severely limited by power consumption and cost. Moreover, strict process flows can impede innovation that would otherwise enable new applications. In an effort to overcome these impediments, we present two modified approaches and applications based on a newly developed process for stretchable and flexible electronics fabrication. This includes the development of a metallization pattern stamping process allowing for 1) stretchable interconnects to be directly integrated with stretchable/wearable fabrics, and 2) a process variation enabling aligned multi-layer devices with integrated ferromagnetic nanocomposite polymer components enabling a fully-flexible electromagnetic microactuator for large-magnitude magnetic field generation. The wearable interconnects are measured, showing high conductivity, and can accommodate over 20% strain before experiencing conductive failure. The electromagnetic actuators have been fabricated and initial measurements show well-aligned, highly conductive, isolated metal layers. These two applications demonstrate the versatility of the newly developed process and suggest potential for its furthered use in stretchable electronics and MEMS applications.

Nano-structure of soft and wet materials are making important roles in radiation therapy, as a three-dimensional (3D) gel dosimeter. In the last decades, radiation therapy instruments have had a large progressive of the accuracy, therefore more precise measurements have became important. We study new materials and apparatus, which measure three dimensional absorbed dose distributions. New materials are double network (DN²) gel and improved PAGAT (yDAGAT) gel, the former has several good points, high transparency, high water content, high mechanical strength, and toughness, the later has similar properties of PAGAT gel but will be more tractable. The new type of optical-CT machine is Scanning Microscopic Light Scattering System (SMILS). Usual optical-CT uses the opacity, which is measured by the intensity, however SMILS also uses dynamic light scattering (DLS) theory with original ensemble average method. By using the intensity and DLS information, more accurate information are expected. We have established one-dimensional measurement by SMILS using irradiated DN gel. Additionally, yDAGAT is successfully composed. In the future, we are planning to develop three-dimensional radiation measurement apparatus by 3D printable gel and 3D SMILS.

Ultrasonic imaging transducer is often required to compose a beam pattern of a low sidelobe level and a small beam width over a long focal region to achieve good image resolution. Normal ultrasound transducers have many channels along its azimuth, which allows easy formation of the sound beam into a desired shape. However, micro-array transducers have no control of the beam pattern along their elevation. In this work, a new method is proposed to manipulate the beam pattern by using an acoustic multifocal lens and a shaded electrode on top of the piezoelectric layer. The shading technique split an initial uniform electrode into several segments and combined those segments to compose a desired beam pattern. For a given elevation width and frequency, the optimal pattern of the split electrodes was determined by means of the OptQuest-Nonlinear Program (OQ-NLP) algorithm to achieve the lowest sidelobe level. The requirement to achieve a small beam width with a long focal region was satisfied by employing an acoustic lens of three multiple focuses. Optimal geometry of the multifocal lens such as the radius of curvature and aperture diameter for each focal point was also determined by the OQ-NLP algorithm. For the optimization, a new index was devised to evaluate the on-axis response: focal region ratio = focal region / minimum beam width. The larger was the focal region ratio, the better was the beam pattern. Validity of the design has been verified through fabricating and characterizing an experimental prototype of the transducer.

ZnO nanorods grown cellulose film is a fascinating inorganic-organic hybrid nanocomposite in terms of synergistic properties with semiconductive functionality of ZnO and renewability and flexibility of cellulose film. This paper reports the fabrication and evaluation of cellulose ZnO hybrid nanocomposite (CEZOHN). ZnO nanorod is well grown on a cellulose film by simple chemical reaction with direct seeding and hydrothermal growing. CEZOHN has unique electric, electro-mechanical and photo-electrical behaviors. The performance of CEZOHN is estimated by measuring induced photocurrent under UV exposure. Mechanism of UV sensing and its possible applications for flexible and wearable UV sensor are addressed.

In these days, consumer electronics and medical device for optical diagnosis are minimalized and mobilized. The focusing part is one of crucial parts of optical diagnosis systems to reduce the size and weight. Thus, demand for tunable lens that change the focus itself is increased. To meet the demand, many tunable lens has been studied by utilizing smart materials that responded under mechanical, magnetic, optical, thermal, chemical, electrical or electrochemical stimuli. This paper reports a cellulose nanocrystal (CNC) and poly[di(ethylene glycol) adipate] (PDEGA) blend that is able to respond under electromechanical stimulus. The preparation of CNC/PDEGA and its characterization are illustrated and its actuation behavior is tested . Because the material has high dielectric constant and high reflection index, it is good candidate material for tunable lens.

One of the abundant renewable biomaterials in the world – cellulose is produced from plants forming micro-fibrils which in turn aggregate of form cellulose fibers. These fibers size can be disintegrated from micro-fibrils to nanofibers by physical and chemical methods. Cellulose nanofibers (CNF) can be a new building block of renewable smart materials. The CNF has excellent mechanical strength, dimensional stability, thermal stability and good optical properties on top of their renewable behavior. This paper reports CNF transparent films made by CNF extracted by the physical method: a high pressure physical, so called aqueous counter collision method. Natural behaviors, extraction and film formation of CNF are explained and their characteristics are illustrated, which is suit for IT applications.

Vertically aligned arrays of ZnO nanowire can be used for many applications such as energy harvesters, UV sensors and mechanical sensors. Here we report the feasibility of a miniaturized accelerometer made with ZnO nanowire. For improving the sensitivity of miniaturized piezoelectric accelerometer, size of piezoelectric ceramic should be large which results in heavy accelerometer and low resonance frequency. To resolve the problem for the miniaturized accelerometer fabrication, ZnO nanowire is chosen. ZnO nanowire, which has piezoelectric property with Wurtzite structure. Since it has high aspect ratio, the use of ZnO nanowire leads to increase deformation and piezoelectric response output. The vertically ZnO nanowire array is grown on a copper substrate by hydrothermal synthesis process. Detail Fabrication process of the miniaturized accelerometer is illustrated. To prove the feasibility of the fabricated accelerometer, dynamic response test is performed in comparison with a commercial accelerometer.

Electroactive hydrogels are attractive for soft robotics and reconfigurable lens applications. Here we describe the design and fabrication of cellulose-poly vinyl alcohol based hydrogels. The fabricated hydrogels were confirmed by Fourier transformer spectroscopy, swelling studies, thermal analysis, surface morphology of fabricated hydrogel was study by using scanning electron microscopy. The effect of poly vinyl alcohol concentration on the optical and electrical behavior of hydrogels was studied.

State of the art smart materials such as piezo ceramics or electroactive polymers cannot feature both, mechanical stiffness and high active strain. Moreover, properties like low density, high mechanical stiffness and high strain at the same time driven by low energy play an increasingly important role for their future application. Carbon nanotubes (CNT), show this behavior. Their active behavior was observed 1999 the first time using paper-like mats made of CNT. Therefore the CNT-papers are electrical charged within an electrolyte thus forming a double- layer. The measured deflection of CNT material is based on the interaction between the charged high surface area formed by carbon nanotubes and ions provided by the electrolyte. Although CNT-papers have been extensively analyzed as well at the macro-scale as nano-scale there is still no generally accepted theory for the actuation mechanism. This paper focuses on investigations of the actuation mechanisms of CNT-papers in comparison to vertically aligned CNT-arrays. One reason of divergent results found in literature might be attributed to different types of CNT samples. While CNT-papers represent architectures of short CNTs which need to bridge each other to form the dimensions of the sample, the continuous CNTs of the array feature a length of almost 3 mm, along which the experiments are carried out. Both sample types are tested within an actuated tensile test set-up under different conditions. While the CNT-papers are tested in water-based electrolytes with comparably small redox-windows the hydrophobic CNT-arrays are tested in ionic liquids with comparatively larger redox-ranges. Furthermore an in-situ micro tensile test within an SEM is carried out to prove the optimized orientation of the MWCNTs as result of external load. It was found that the performance of CNT-papers strongly depends on the test conditions. However, the CNT-arrays are almost unaffected by the conditions showing active response at negative and positive voltages. A micro alignment as result of tensile stress can be proven. A comparison of both results point out that the actuation mechanism strongly depends on the weakest bonds of the architectures: Van-der-Waals-bonds vs. covalent C-bonds.

In a dual-carrier vital sign detection system, we have designed a noise suppression scheme that uses phase locked loop (PLL) to automatically suppress the noise induced by range correlation and transmission paths. The system uses two microwave carriers at 5.6 and 5.68 GHz generated by two phase locked signal generators to extract the noise and vital sign respectively. The feedback microwave signals are mixed with local 5.68-GHz signal to transfer to the vial sign signal and low frequency intermediate frequency (IF) signal. When the IF signal corresponding to 5.68 GHz microwave signal is locked to a highly stable low noise reference, the noises of IF signal and vital sign signal are suppressed as their corresponding microwave signals are highly correlated. In this system, the noise suppression performance is related to the bandwidth of the PLL, which needs to be carefully designed. Through the theoretical analysis, initial bandwidth is chosen to be 200 Hz. Then the charge pump current is changed to adjust the bandwidth and the corresponding noise suppression performance is evaluated using experiments. The results show the system with a charge pump current 0.625 mA, which corresponds to about 50 Hz bandwidth, exhibits a better noise performance. In addition, at different bandwidth, the vital sign detection system is compared with a design scheme with unlocked PLL and demonstrates superior performance at all bandwidths.

The integration of wireless power transmission devices using microwaves into the biomedical field is close to a practical reality. Implanted biomedical devices need a long lasting power source or continuous power supply. Recent development of high efficiency rectenna technology enables continuous power supply to these implanted devices. Due to the size limit of most of medical devices, it is imperative to minimize the rectenna as well. The research reported in this paper reviews the effects of close packing the rectenna elements which show the potential of directly empowering the implanted devices, especially within a confined area. The rectenna array is tested in the X band frequency range.

Football players are more to violent impacts and injuries more than any athlete in any other sport. Concussion or mild traumatic brain injuries were one of the lesser known sports injuries until the last decade. With the advent of modern technologies in medical and engineering disciplines, people are now more aware of concussion detection and prevention. These concussions are often overlooked by football players themselves. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. The principle of concussion is based the movement of the brain in the neurocranium and viscerocranium. The brain is encapsulated by the cerebrospinal fluid which acts as a protective layer for the brain. This fluid can protect the brain against minor movements, however, any rapid movements of the brain may mitigate the protective capability of the cerebrospinal fluid. In this paper, we propose a wireless health monitoring helmet that addresses the concerns of the current monitoring methods - it is non-invasive for a football player as helmet is not an additional gear, it is efficient in performance as it is equipped with EEG nanosensors and 3D accelerometer, it does not restrict the movement of the user as it wirelessly communicates to the remote monitoring station, requirement of individual monitoring stations are not required for each player as the ZigBee protocol can couple multiple transmitters with one receiver. A helmet was developed and validated according to the above mentioned parameters.

Neurocardiology is the exploration of neurophysiological, neurological and neuroanatomical facets of neuroscience’s influence in cardiology. The paraphernalia of emotions on the heart and brain are premeditated because of the interaction between the central and peripheral nervous system. This is an investigative attempt to study emotion based neurocardiology and the factors that influence this phenomena. The factors include: interaction between sleep EEG (electroencephalogram) and ECG (electrocardiogram), relationship between emotion and music, psychophysiological coherence between the heart and brain, emotion recognition techniques, and biofeedback mechanisms. Emotions contribute vitally to the mundane life and are quintessential to a numerous biological and everyday-functional modalities of a human being. Emotions are best represented through EEG signals, and to a certain extent, can be observed through ECG and body temperature. Confluence of medical and engineering science has enabled the monitoring and discrimination of emotions influenced by happiness, anxiety, distress, excitement and several other factors that influence the thinking patterns and the electrical activity of the brain. Similarly, HRV (Heart Rate Variability) widely investigated for its provision and discerning characteristics towards EEG and the perception in neurocardiology.

ZnO nanowires (NWs) would provide significant enhancement in sensitivity due to high surface to volume ratio. We investigated the first methodical study on the quantitative relationship between the process parameters of solution concentration ratio, structure, and physical and properties of ZnO NWs grown on different flexible fabric surfaces. To develop a fundamental following concerning various substrates, we controlled the growth speed of ZnO NWs and nanowires on cotton surface with easy and moderate cost fabrication method. Using ammonium hydroxide as the reactant with zinc nitrate hexahydrate, ZnO NWs layer have been grown on metal layers, instead of seed layer. ZnO NWs fabrication was done on different fabric substrates such as wool, nylon and polypropylene (PP). After the ZnO NWs grown to each substrates, we coated insulating layer with polyurethane (PU) and ethyl cellulose for prevent external intervention. Detailed electrical characterization was subsequently performed to reveal the working characteristics of the hybrid fabric. For electrical verification of fabricated ZnO NWs, we implemented measurement impact test and material properties with FFT analyzer and LCR meter.

T wave alternans (TWA) is the variation of the T-wave in electrocardiogram that is observed between periodic beats. TWA is one of the important precursors used to diagnose sudden cardiac death (SCD). Several clinical studies have tried to determine the significance of using TWA analysis to detect abnormalities that may lead to Ventricular Arrhythmias, as well as establish metrics to perform risk stratification for cardiovascular patients with prior cardiac episodes. The statistical significance of TWA in predicting ventricular arrhythmias has been established in patients across several diagnoses. Studies have also shown the significance of the predictive value of TWA analysis in post myocardial infarction patients, risk of SCD, congestive heart failure, ischemic cardiomyopathy, and Chagas disease.

A good night's sleep plays a vital role in physical and mental wellbeing by performing the recuperative function for the brain and the body. Notwithstanding the fact that, good sleep is an essential part of a person's life, an increasing number of people are experiencing sleep disorders and loss of sleep. According to the research by the National Institutes of Health (NIH), 50 to 70 million Americans suffer from sleep disorders and sleep deprivation. Although sleep disorder is a highly prevalent condition like diabetes or asthma, 80 to 90 percent of the cases remain undiagnosed. The short-term effects of sleep disorder are morning headaches, excessive daytime sleepiness, shot-term memory loss and depression, but the cumulative long-term effects result in severe health consequences like heart attacks and strokes. In addition, people suffering from sleep disorders are 7.5 times more likely to have a higher body mass index and 2.5 times more likely to have diabetes. Further, undiagnosed and untreated sleep disorders have a significant direct and indirect economic impact. The costs associated with untreated sleep disorders are far higher than the costs for adequate treatment. According to the survey, approximately 16 billion of dollars are spent on medical expenses associated with repeated doctor visits, prescriptions and medications.

Detection of sleepiness and drowsiness in human beings has been a daunting task for both engineering and medical technologies. Accuracy, precision and promptness of detection have always been an issue that has to be dealt by technologists. Generally, the bio potential signals – ECG, EOG, EEG and EMG are used to classify and discriminate sleep from being awake. However, the potential drawbacks may be high false detections, low precision, obtrusiveness, aftermath analysis, etc. To overcome the disadvantages, this paper reviews the design aspects of a wireless and a real time monitoring system to track sleep and detect fatigue. This concept involves the use of EOG and EEG to measure the blink rate and asses the person’s condition. In this user friendly and intuitive approach, EOG and EEG signals are obtained by the textile based nanosensors mounted on the inner side of a flexible headband. The acquired signals are then electrically transmitted to the data processing and transmission unit, which transmits the processed data to the receiver/monitoring module through ZigBee communication. This system is equipped with a software program to process, feature extract, analyze, display and store the information. Thereby, immediate detection of a person falling asleep is made feasible and, tracking the sleep cycle continuously provides an insight about the fatigue level. This approach of using a wireless, real time, dry sensor on a flexible substrate mitigates obtrusiveness that is expected from a wearable system. We have previously presented the results of the aforementioned wearable systems. This paper aims to extend our work conceptually through a review of engineering and medical techniques involved in wearable systems to detect drowsiness.

Dynamic characteristics of smart composite laminate with partially debonded piezoelectric sensor are investigated. Improved layerwise theory with Heaviside’s unit step function is used to model the discontinuous displacement field with jumps owing to the in-plane slipping and out-of-plane opening at the debonded interface. Higher order electric potential field is employed to describe the potential variation through the thickness of piezoelectric patches. Finite element method and extended Hamilton’s principle are used to derive the governing equation of motion. The governing equation is solved in time domain using Newmark time integration algorithm. The developed model is numerically implemented on a laminated composite plate with surface bonded piezoelectric actuator and partially debonded sensor. The sensing capability is evaluated in the presence of partial inner and edge debonding in the piezoelectric sensor.

The detection of explosives and their residues is of great importance in public health, antiterrorism and homeland security applications. The vapor pressures of most explosive compounds are extremely low and attenuation of the available vapor is often great due to diffusion in the environment, making direct vapor detection difficult. In this paper, a photonic-microfluidic integrated sensor for highly sensitive 2,4,6-trinitrotoluene (TNT) detection is described based on an in-fiber Mach-Zehnder interferometer (MZI) in a photonic crystal fiber (PCF). A segment of PCF is inserted between standard single-mode fibers (SMF) via butt coupling to form a modal interferometer, in which the cladding modes are excited and interfere with the fundamental core mode. Due to butt coupling, the small air gap between SMF and PCF forms a coupling region and also serves as an inlet/outlet for the gas. The sensor is fabricated by immobilizing a chemo-recognition coating on the inner surface of the holey region of the PCF, which selectively and reversibly binds TNT molecules on the sensitized surface. The sensing mechanism is based on the determination of the TNT-induced wavelength shift of interference peaks due to the refractive index change of the holey-layer. The sensor device therefore is capable of field operation.

In modern Minimally Invasive Spine Surgery (MISS), lack of visualization and haptic feedback information are the main obstacles. The spinal cord is a part of the central nervous system (CNS). It is a continuation of the brain stem, carries motor and sensory messages between CNS and the rest of body, and mediates numerous spinal reflexes. Spinal cord and spinal nerves are of great importance but vulnerable, once injured it may result in severe consequences to patients, e.g. paralysis. Raman Spectroscopy has been proved to be an effective and powerful tool in biological and biomedical applications as it works in a rapid, non-invasive and label-free way. It can provide molecular vibrational features of tissue samples and reflect content and proportion of protein, nucleic acids lipids etc. Due to the distinct chemical compositions spinal nerves have, we proposed that spinal nerves can be identified from other types of tissues by using Raman spectroscopy. Ex vivo experiments were first done on samples taken from swine backbones. Comparative spectral data of swine spinal cord, spinal nerves and adjacent tissues (i.e. membrane layer of the spinal cord, muscle, bone and fatty tissue) are obtained by a Raman micro-spectroscopic system and the peak assignment is done. Then the average spectra of all categories of samples are averaged and normalized to the same scale to see the difference against each other. The results verified the feasibility of spinal cord and spinal nerves identification by using Raman spectroscopy. Besides, a fiber-optic Raman sensing system including a miniature Raman sensor for future study is also introduced. This Raman sensor can be embedded into surgical tools for MISS.

The main focus of the paper is the development of technological route of the production of complex 3D microstructure, from designing it by the method of computer generated holography till its physical 3D patterning by exploiting the process of electron beam lithography and thermal replication which is used for biomedical application. A phase data of a complex 3D microstructure was generated by using Gerchberg-Saxton algorithm which later was used to produce a computer generated hologram. Physical implementation of microstructure was done using a single layer polymethyl methacrylate (PMMA) as a basis for 3D microstructure, which was exposed using e-beam lithography system e-Line and replicated, using high frequency vibration. Manufactured 3D microstructure is used for designing micro sensor for biomedical applications.

Light microscopy can not only address various diagnosis needs such as aquatic parasites and bacteria such as E. coli in water, but also provide a method for the screening of red tide. Traditional microscope based on the smartphone created by adding lens couldn’t keep the tradeoff between field-of-view(FOV) and the resolution. In this paper, we demonstrate a non-contact, light and cost-effective microscope platform, that can image highly dense samples with a spatial resolution of ~0.8um over a field-of-view(FOV) of >1mm². After captured the direct images, we performed the pixel super-resolution algorithm to improve the image resolution and overcome the hardware interference. The system would be a good point-of-care diagnostic solution in resource limited settings. We validated the performance of the system by imaging resolution test targets, the squamous cell cancer(SqCC) and green algae that necessary to detect the squamous carcinoma and red tide

Simple, reliable, lightweight, and inexpensive thin films based sensors are still in intense development and high demand in many applications such as biomedical, industrial, environmental, military, and consumer products. One important class of sensors is the optical pH sensor. In addition, conformal thin film based sensors extend the range of application for pH optical sensors. We present the results on the fabrication and characterization of optical pH sensing coatings made through ionic self-assembled technique. These thin films are based on the combination of a polyelectrolyte and water-soluble organic dye molecule Direct Yellow 4. A series of films was fabricated and characterized in order to determine the optimized parameters of the polymer and of the organic dye solutions. The optical pH responses of these films were also studied. The transparent films were immersed in solutions at various temperature and pH values. The films are stable when immersed in solutions with pH below 9.0 and temperatures below 90 °C and they maintain their performance after longer immersion times. We also demonstrate the functionality of these coatings as conformal films.

This paper presents modeling, analysis techniques and experiment of foam metal metamaterial panel for Broadband Vibration Absorption. For a unit cell of an infinite foam metal metamaterial panel, governing equations are derived using the extended Hamilton principle. The concepts of negative effective mass and stiffness and how the spring-mass-damper subsystems create a stopband are explained in detail. Numerical simulations reveal that the actual working mechanism of the proposed metamaterial panel is based on the concept of conventional mechanical vibration absorbers. It uses the incoming elastic wave in the panel to resonate the integrated membrane-mass-damper absorbers to vibrate in their optical mode at frequencies close to but above their local resonance frequencies to create shear forces and bending moments to straighten the panel and stop the wave propagation. Moreover, a two-dimension acoustic foam metal metamaterial panel consisting of lumped mass and elastic membrane is proposed in the lab. We do experiments on the model and The results validate the concept and show that, for two-dimension acoustic foam metal metamaterial panel do exist two vibration modes. For the wave absorption, the mass of each cell should be considered in the design. With appropriate design calculations, the proposed two-dimension acoustic foam metal metamaterial panel can be used for absorption of low-frequency waves and hence expensive micro-manufacturing techniques are not needed for design and manufacturing of such foam metal metamaterial panel for low-frequency waves absorption/isolation.

Ultrasonic haptics actuator is a device that can create a haptic feedback to user’s hand. The modulation of ultrasonic frequency can give different textures to the users. In this study, a feasibility of the ultrasonic haptic actuator made on a flexible piezoelectric substrate is investigated. As the piezoelectric substrate helps to propagate flexural waves, a pair of interdigital transducer (IDT) with reflectors can produce standing waves, which can increase the vibrational displacement of the actuator. A pair of IDT pattern was fabricated on a piezoelectric polymer substrate. A finite element analysis is at first performed to design the actuator. A sinusoidal excitation voltage is applied on IDT electrodes at ultrasonic frequencies and the displacement waveforms are found. The displacement waveforms clearly represent how ultrasonic waves propagate through the piezoelectric substrate.

The aim of this article is to investigate the effect of two different fixation hardware materials on bone remodeling after a mandibular reconstruction surgery and to restore the mandible’s function, healthy appearance, mastication, swallowing, breathing, and speech. The hypothesis is that using fixation hardware with stiffness close to that of the surrounding bone will result in a more successful healing process in the mandible bone. The finite element model includes the material properties and forces of the cancellous bone, cortical bone, ligaments, muscles, and teeth. The reconstruction surgery is modeled by including the fixation hardware and the grafted bone. In the sectioned mandible, to best mimic the geometry of the mandible, two single barrel grafts are placed at the top of each other to form a double barrel graft set. Two different materials were used as the mandibular fixation parts, stiff Ti-6Al-4V, and porous superelastic Nickel-Titanium (NiTi) alloys. A comparison of these two alloys demonstrates that using porous NiTi alloy as the fixation part results in a faster healing pace. Furthermore, the density distribution in the mandibular bone after the healing process is more similar to the normal mandible density distribution. The simulations results indicate that the porous superelastic NiTi fixation hardware transfers and distributes the existing forces on the mandible bone more favorably. The probability of stress shielding and/or stress concentration decrease. This type of fixation hardware, therefore, is more appropriate for mandible bone reconstruction surgery. These predictions are in agreement with the clinical observations.

Proton exchange membrane (PEM) fuel cells are considered to be the promising alternatives of natural resources for generating electricity and power. An optimal water management in the gas diffusion layers (GDL) is critical to high fuel cell performance. Its basic functions include transportation of the reactant gas from flow channels to catalyst effectively, draining out the liquid water from catalyst layer to flow channels, and conducting electrons with low humidity. In this study, polyacrylonitrile (PAN) was dissolved in a solvent and electrospun at various conditions to produce PAN nanofibers prior to the stabilization at 280 °C for 1 hour in the atmospheric pressure and carbonization at 850 °C for 1 hour. The surface hydrophobicity values of the carbonized PAN nanofibers were adjusted using superhydrophobic and hydrophilic agents. The thermal, mechanical, and electrical properties of the new GDLs depicted much better results compared to the conventionally used ones. The water condensation tests on the surfaces (superhydrophobic and hydrophilic) of the GDL showed a crucial step towards improved water managements in the fuel cell. This study may open up new possibilities for developing high- performing GDL materials for future PEM fuel cell applications.