This PDF file contains the front matter associated with SPIE Proceedings Volume 6931, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Micro sensors offer the potential solution to cost, size, and weight issues associated with smart networked sensor systems designed for environmental/missile health monitoring and rocket out-gassing/fuel leak detection, as well as situational awareness on the battlefield. In collaboration with the University of Arkansas (Fayetteville), University of Alabama (Tuscaloosa and Birmingham), Alabama A&M University (Normal), and Streamline Automation (Huntsville, AL), scientists and engineers at the Army Aviation & Missile Research, Development, and Engineering Center (AMRDEC) are investigating several nano-based technologies to solve the problem of sensing extremely small levels of toxic gases associated with both chemical warfare agents (in air and liquids) and potential rocket motor leaks. Innovative techniques are being devised to adapt voltammetry, which is a well established technique for the detection and quantification of substances dissolved in liquids, to low-cost micro sensors for detecting airborne chemical agents and potential missile propellant leakages. In addition, a surface enhanced Raman scattering (SERS) technique, which enhances Raman scattered light by excitation of surface plasmons on nanoporous metal surfaces (nanospheres), is being investigated to develop novel smart sensors for the detection of chemical agents (including rocket motor out-gassing) and potential detection of home-made explosive devices. In this paper, results are delineated that are associated with experimental studies, which are conducted for the aforementioned cases and for several other nano-based technology approaches. The design challenges of each micro sensor technology approach are discussed. Finally, a comparative analysis of the various innovative micro-sensor techniques is provided.

pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages in specific applications. It is difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to size limitation and no deformability. In this paper, we present design and fabrication processes of a miniature iridium oxide thin film pH sensor array on flexible polymer substrates. The amorphous iridium oxide thin film was used as the sensing material. A sol-gel dip-coating process of iridium oxide film was demonstrated in this paper. A super-Nernstian response has been measured on individual sensors of the array with a slope of -71.6±3 mV/pH at 25°C within the pH range between 2.83 and 11.04.

The paper describes a disposable electrochemical biosensor for glucose monitoring. The sensor is based on carbon paste immobilized with glucose oxidase and upon screen printed electrodes. The sensor has been tested effectively for the blood glucose levels corresponding to normal (70 to 99 mg/dL or 3.9 to5.5 mmol/L), pre-diabetic (100 to 125 mg/dL or 5.6 to 6.9 mmol/L) and diabetic (>126 mg/dL or 7.0 mmol/L). The calibration curve and the sensitivity of the sensor were measured.

Materials with nanoscale features have new or improved properties compared to bulk materials. These properties depend on the composition, size, and shape of the material, and include high specific strength and modulus, low melting point, high electrical and thermal conductivity, a large surface area to volume ratio, nearly defect-free structure, magnetic and optical properties, and sensing and actuation properties. This talk will discuss synthesis, processing, and application of nanoscale materials for engineering and medicine. Recent advances in nanoparticle synthesis include development of "Black Cotton" which is centimeter long carbon nanotubes grown in arrays, improved carbon nanofiber material, and development of carbon nanosphere chain material which has the morphology of carbon onions chained together. Applications of these materials under development include spinning Black Cotton into thread to produce a new smart material with reinforcement, sensing, and actuation properties, use of nanotube arrays for electrodes and biosensors, catalyst loaded nanotubes for medical contrast agents, and nanosphere chains for manufacturing composite materials. Overall, this paper shows that "Nanoizing" materials and structures is a hot new technological science that is going to improve many aspects of our lives. These new materials are also generating intellectual property and new opportunities for small companies and universities.

Current transport in carbon nanotube field effect transistors (CNT-FETs) has been modeled from charge distributions and the potential inside the carbon nanotube. Analytical equations describing I-V characteristics of the CNT-FETs have been obtained from the combination of diffusion and drift mechanisms in the channel region for normal and sub-threshold operations. It is shown that the electronic transport in semiconducting single-walled carbon nanotubes and field effect transistors can provide better understanding of their bio- and chemical sensing for the detection of traces of agents at molecular levels.

There is a strong interest in the use of conductive shape memory polymer (SMP) for actuation by passing an electrical current. This paper presents a systematic study on the effect of multi-walled carbon nanotubes (MWCNTs) and carbon nanoparticles on the electro activate shape memory polymer (SMP). The first is the fabrication and characterization of styrene-based SMP filled with MWCNTs was investigated. Then the resistivity of 8 wt% MWNTs sample is 80 ohm•cm obtained by using four-point probe Van De Pawn method, and for 8.0×2.0×0.2 cm³ rectangle sheet, it can be triggered by passing an electrical current with a constant voltage of 200 V. The second is focused on the effect of conductive particulate and fibrous fillers on the electrical property of composite. The electrical conductivity of the composites achieves 8.73×10^-2, 9.63×10^-2 and 1.13×10^-1 S/cm by DC measurement and 0.12, 1.05 and 3 S/cm by four-point probe Van De Pauw method. Their shape recovery can be activated by passing an electrical current of 25 V voltages. In this paper, the sensors using conducting SMP composites testified by the temperature-dependent resistance and strain-dependent resistance tests. At the same time, the shape self-recovery of SMPs and their composites when heated above transition temperature acts as actuator.

Significant amount of pentacene can be dissolved in N-methylpyrrolidone (NMP) solvent. The solution color changed from deep purple to intense yellow. As the dissolution time increased, UV-visible absorption increased and several new absorption peaks were appeared. The solution was mixed with poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS). PEDOT:PSS or PEDOT:PSS doped with pentacene was spin-coated to the Al coated substrate. Au-electrode was fabricated on top of the semiconductor. Three-layered Schottkys diode comprised of Al, PEDOT:PSS or PEDOT:PSS-pentacene, and Au with thickness of 150nm, 420nm, and 1200nm, respectively were fabricated. The current densities of 4.8μA/cm² at 2.5MV/m and 440μA/cm² at 1.9MV/m were obtained for the Au/PEDOT:PSS/Al and Au/PEDOT:PSS-pentacene (3.2 mg)/Al Schottky diodes, respectively. The current density of Schottky diode enhanced about two order of magnitude by doping pentacene to PEDOT:PSS.

A major concern in the development of microelectromechanical systems (MEMS) is the presence of residual stress. This stress, which is produced during the fabrication of multi-layer thin-film structures, can significantly affect the performance of micro-scale devices. Though experimental measurement techniques are accurate, actual stress measurements can vary dramatically from run to run and wafer to wafer. For this reason, the modeling of this stress can be a challenging task. Past work has often focused on experimental, static techniques for determining residual-stress levels in single-layer and bi-layer structures. In addition, in prior studies, the focus has primarily been on residual-stress measurements in thin films as they are being deposited and prior to the release of a particular device. In this effort, residual stresses in MEMS resonators are characterized pre- and post-micro-machining and release of the structures. This is accomplished by applying three residual-stress identification techniques. The first technique, which is based on wafer-bow measurements and Stoney's formula, is suited for determining the residual stresses in thin film layers as they are being deposited and before the occurrence of a micro-machining or release process. In the second technique, a static parametric identification technique, device deflection data is made use of to approximate individual device residual stress immediately after release of a structure. The third technique, a dynamic parametric identification technique, which can be based on linear or nonlinear frequency response data can be used to estimate device residual stress immediately after release and after the device has been polarized. The results obtained by using these techniques are used to develop an understanding of how geometry, fabrication, release and polarization of resonators affect the stress state in a piezoelectric device. The results, which show that the stress levels can be quite different after a device has been released and poled, point to the importance of considering parameter identification schemes such as those described in this effort for identifying residual stresses in multi-layer, micro-structures.

A cellulose solution was prepared using N,N-dimethylacetamide (DMAc), LiCl, and natural pulp. Transparent and smooth surface of the cellulose films were obtained after spin-coating and drying process. The cellulose films can be utilized as a biodegradable and flexible microelectromechanical system (MEMS) due to its electro-active and actuation properties. However, it is difficult to apply conventional lithography process to fabricate MEMS device because of its hydrophilic and flexible nature. Therefore, we applied unconventional lithography process to overcome those problems. Since polydimethylsiloxane (PDMS) has a modulus less than 10MPa, it is not suitable to fabricate high aspect ratio mold. Polyurethaneacrylate (PUA) having a modulus in the range of several hundred was utilized as a mold for micro-contact printing (MCP) process. Although high modulus PUA mold having more than 300MPa had edge defects during the mold-releasing process from the photoresist, the PUA mold having a modulus between 100MPa and 300MPa did not have the edge defect problem. Therefore, PUA mold with a modulus of 200MPa was used in this investigation. Gold was deposited onto the PUA mold, and mercaptopropyltrimethoxysilane (MPTMS) self-assembly monolayer (SAM) was fabricated to the gold surface. The gold was transferred to the cellulose film. The characteristics of the transferred gold electrode on cellulose film were investigated using field emission scanning electron microscope (FESEM).

Shape memory polymer (SMP) receives increasing attention along with its derivants - SMP composite and SMP foam in recent years. In this paper, after fabricating thermoset styrene-based SMP, SMP/carbon black (CB) composite and SMP foam, we studied their shape recovery speed in bending. Different from those reported in the literature, we propose a new approach, i.e., using infrared light, for actuating SMP materials for shape recovery. The results show that SMP, SMP/CB composite and SMP foam can recover to their original shape perfectly in a wide temperature range. Shape recovery speed of SMP composite is not uniform during the overall recovery process, and it is the same trend with SMP but not prominent with SMP foam. Repeatability of shape recovery speed for styrene-based SMP and SMP/CB composite are similarly stable and the former is the better, but it is so worse for SMP foam. Temperature-dependent of shape recovery speed test for styrene-based SMP and SMP/CB composite reveal that higher temperature increases their shape recovery speed.

The paper describes the synthesis of vertically aligned CNTs and the development of magnetic nanotube substrates for biological applications. The vertical alignment of the CNTs on a silicon substrate for the use in biological sensor systems has been explored. The preliminary experiments to determine the binding and growth of biological samples with CNTs have been described. The potential to use the CNTs as electrode for elctrical stimulation is explored. The growth of magnetic nanotubes and the possibility of utilizing them as scaffold for cellular growth is demonstrated. The paper also described the sythesis and development of the magnetic carbon nanotubes, combining the salient features of the CNTs and MNTs. All the nanotubes are optically charaterizd using SEM and TEM techniques. The magentization of the nanotubes are evaluated using the VSM. Cellular binding is determined using SEM and flourescent microscopy images.

Cellulose is a beneficial material that has low cost, light weight, high compatibility, and biodegradability. Recently electro-active paper (EAPap) composed with cellulose was discovered as a smart material for application to variety industrial fields such as smart wall-paper, actuator, and magic carpet. It also exhibited actuator property through ion migration and piezoelectric effect. Since cellulose acetate (CA) film has optically transparent property, we focused on optical field application, such as electronic paper, prismsheet, and polarized film. Since CA can be easily dissolved in variety of organic solvent, various weight % (from 1 to 25 wt. %) of CA solution in acetone was prepared. Polydimethylsilane (PDMS) master pattern was fabricated on the silicone wafer. CA solution was poured to the master mold and dried using spin-coating or tape casting method. Various shape and height patterns, such as circle, honeycomb, and rectangular patterns were fabricated using 12 wt. % CA solution. The resulting pattern showed uniform size in the large area without defect. These patterns can be utilized as a substrate and cell pattern for the electronic paper. To investigate saponification (SA) effect to convert CA to regenerated cellulose, CA film was immersed into the sodium methoxide solution in methanol for various times. The fabricated CA films were stretched and immersed into the sodium methoxide solution in methanol to desubstitute the acetate group. These regenerated cellulose films have larger mechanical strength than CA films. Although the UV-visible transmittance was decreased as increasing SA time, the transmittance of the further SA process and stretched film backed up near untreated CA film. Although the cross-sectional image of the saponified and unstretched CA film did not have specific directional structure, the cross-sectional FESEM image of the saponified and stretched CA film had one directional fiber structure. The fiber was aligned to the stretched direction. Most of the compositions were one directional ordered nanofibers having diameter of approximately 30nm.

Myocardial Ischemia is a condition which affects millions of people in the U.S. It is known that a rise in levels of extracellular potassium indicates the onset of this condition. This presentation demonstrates the fabrication of a unique potassium sensing device which combines a conducting polymer, polypyrrole, with micro/nano fabrication and nanowire technology. We discuss the fabrication of gold/polypyrrole electrodes on a flexible polyimide substrate. Conducting polymers offer numerous advantages when it comes to ion sensing including increased stability in response while micro/nanofabrication aids in the overall miniaturization. The small size and flexibility makes this device suitable for future biomedical applications involving implantation. In this presentation, various electrode structures including nanowire electrodes ware investigated. Testing is conducted with an electrochemical analyzer where changes in open circuit potentials reflect changes in potassium ion concentration.

Ion Sensitive Field Effect Transistors (ISFETs) for sensing change in ionic concentration in biological systems can be used for detecting critical conditions like Myocardial Ischemia. Having the ability to yield steady signal characteristics can be used to observe the ionic concentration gradients which mark the onset of ischemia. Two ionic concentrations, pH and [K⁺], have been considered as the indicator for Myocardial Ischemia in this study. The ISFETs in this study have an organic semi-conductor film as the electronically active component. Poly-3 hexylthiophene was chosen for its compatibility to the solution processing, which is a simple and economical method of thin film fabrication. The gate electrode, which regulates the current in the active layer, has been employed as the sensor element. The devices under study here were fabricated on a flexible substrate PEN. The pH sensor was designed with the Tantalum Oxide gate dielectric as the ion selective component. The charge accumulated on the surface of the metal oxide acts as the source of the effecter electric field. The device was tested for pH values between 6.5 and 7.5, which comprises the variation observed during ischemic attack. The potassium ion sensor has got a floating gate electrode which is functionalized to be selective to potassium ion. The device was tested for potassium ion concentration between 5 and 25 mM, which constitutes the variation in extra cellular potassium ion concentration during ischemic attack. The device incorporated a monolayer of Valinomycin, a potassium specific ionophore, on top of the gate electrode.

Wearable health monitoring systems have recently attracted widespread interest for their application in long term patient monitoring. Wireless wearable technology enables continuous observation of patients while they perform their normal everyday activities. This involves the development of flexible and conformable sensors that could be easily integrated to the smart fabrics. Carbon nanotubes are found to be one of the ideal candidate materials for the design of multifunctional e-textiles because of their capability to change conductance based on any mechanical deformation as well as surface functionalization. This paper presents the development and characterization of a carbon nanotube (CNT)-polymer nanocomposite flexible strain sensor for wearable health monitoring applications. These strain sensors can be used to measure the respiration rhythm which is a vital signal required in health monitoring. A number of strain sensor prototypes with different CNT compositions have been fabricated and their characteristics for both static as well as dynamic strain have been measured.

In this study, a high performance peristaltic micropump has been developed and investigated. The micropump has three cylinder chambers which are connected through micro-channels for high pumping pressure performance. A circular-shaped mini LIPCA has been designed and manufactured for actuating diaphragm. In this LIPCA, a 0.1mm thickness PZT ceramic is used as an active layer. As a result, the actuator has shown to produce large out of plane deflection and consumed low power. During the design process, a coupled field analysis was conducted to predict the actuating behavior of a diaphragm and pumping performance. MEMS technique was used to fabricate the peristaltic micropump. Pumping performance of the present micropump was investigated both numerically and experimentally. The present peristaltic micropump was shown to have higher performance than the same kind of micropump developed else where.

Flexible dipole rectenna devices offer an attractive source for the delivery of power to high altitude airships, MAVs (Micro-Aero Vehicles), and smart robots. The power converted by the rectenna can vary due to the distance and receiving angle of the source. Regulating the voltage and current delivered to the system will be critical to the proper operation of the remote device. There are various choices for the regulation of the power received and their applicability was explored. Several available regulators were explored in this research. Zener diodes, series pass regulators, three terminal and switching mode regulators were tested to determine which produced the best performance for the application of powering a remote controlled airship. The present research sought to provide stable voltage and current delivered by an array of rectenna.

This paper presents millimeter wave identification (MMID) concept, which extends the Radio frequency identification (RFID) systems to millimeter wave frequencies. The MMID system is described as well as experimental demonstrations are presented both at 60 GHz and 77 GHz.

The capsule endoscope, a new application area of digital imaging, is growing rapidly but needs the versatile imaging capabilities such as auto-focusing and zoom-in to be an active diagnostic tool. The liquid lens based on MEMS technology can be a strong candidate because it is able to be small enough. In this paper, a cylinder-type liquid lens was designed based on Young-Lippmann model and then fabricated with MEMS technology combining the silicon thin-film process and the wafer bonding process. The focal length of the lens module including the fabricated liquid lens was changed reproducibly as a function of the applied voltage. With the change of 30V in the applied bias, the focal length of the constructed lens module could be tuned in the range of about 42cm. The fabricated liquid lens was also proven to be small enough to be adopted in the capsule endoscope, which means the liquid lens can be utilized for the imaging capability improvement of the capsule endoscope.

This paper details the improvement of image quality of the previously developed piezoelectric driven 2D Optical Display system using an optical fiber waveguide. The current display system is able to produce a desired image (FPGA input) via the oscillation of a micro-fabricated cantilever waveguide or an optical fiber "pixel" driven by two piezoelectric actuators in perpendicular arrangements; however, the image produced is blurred and unstable. To sharpen the image and allow a more detailed image to be displayed, a more refined output "pixel" is needed. To obtain such a "pixel", optical fibers with a tapered tip and metallic deposits is to be used on the output end. The use of the tapered fiber as a waveguide reduces the light that was being misguided by the cladding of the fiber and produces a finer "pixel" at each point of the image, reducing the blurriness of the displayed image. A closed loop feedback control was also added because the existing system requires manual frequency calibration to find the proper frequency to display the image after each system reset. The added control will find the proper frequency by matching the input image and the output image via image recognition coding in MATLAB and adjust the system to the optimal display frequency at the initialization of the system.

Carbon nanotube based electrodes can overcome the drawbacks posed by the conventional wet electrodes, used for physiological monitoring. Here, multiwalled CNT arrays were grown on highly doped n-type Si-wafers with Fe-catalyst layer, using a thermal CVD system. Acetylene was used as the carbon source gas, while Ammonia was the reducing gas and Argon was the purging inert gas, in these experiments. The thermal annealing of the catalyst layer and the carbon nanotube growth schedule, were optimized to get a dense and uniform multiwalled CNT array. SEM images reveal dense uniform growth of multiwalled carbon nanotubes over the entire catalyst deposited area. The cross-sectional images reveal a quasi-vertical alignment.

The bioelectrical potentials generated within the human body are the result of electrochemical activity in the excitable cells of the nervous, muscular or glandular tissues. The ionic potentials are measured using biopotential electrodes which convert ionic potentials to electronic potentials. The commonly monitored biopotential signals are Electrocardiogram (ECG), Electroencephalogram (EEG) and Electromyogram (EMG). The electrodes used to monitor biopotential signals are Ag-AgCl and gold, which require skin preparation by means of scrubbing to remove the dead cells and application of electrolytic gel to reduce the skin contact resistance. The gels used in biopotential recordings dry out when used for longer durations and add noise to the signals and also prolonged use of gels cause irritations and rashes to skin. Also noises such as motion artifact and baseline wander are added to the biopotential signals as the electrode floats over the electrolytic gel during monitoring. To overcome these drawbacks, dry electrodes are used, where the electrodes are held against the skin surface to establish contact with the skin without the need for electrolytic fluids or gels. The major drawback associated with the dry electrodes is the high skin-electrode impedance in the low frequency range between 0.1-120 Hz, which makes it difficult to acquire clean and noise free biopotential signals. The paper presents the design and development of biopotential data acquisition and processing system to acquire biopotential signals from dry electrodes. The electrode-skin-electrode- impedance (ESEI) measurements was carried out for the dry electrodes by impedance spectroscopy. The biopotential signals are processed using an instrumentation amplifier with high CMRR and high input impedance achieved by boot strapping the input terminals. The signals are band limited by means of a second order Butterworth band pass filters to eliminate noise. The processed biopotential signals are digitized and transmitted wirelessly to a remote monitoring station.

This paper presents a starting study of carbon nanotube usefulness in microwave applications, mainly in the field of nano-antenna and nano-switches. We reviewed first the main structural, mechanical, thermal and electrical properties of carbon nanotubes. Then we started studying the possibilities offered by metallic carbon nanotubes as nano-antennas in the E- and W- bands and further comparison with macroscopic wire antennas and the major advantages brought by nanotubes but also the technical issues to be addressed. Finally we are looking into the integration of carbon nanotubes in nano-electro-mechanical-systems (NEMS) through nano-switches. The contribution of carbon nanotubes is detailed with a state-of-the-art as well as our future approaches for such nano devices.

As the power consumption of modern electronics and wireless circuits decreases to a few hundred microwatts, it becomes possible to power these electronic devices by using ambient energy harvested from the environment. Mechanical vibration is among the more pervasive ambient available energy forms. Recent works in vibration-to-electrical energy harvesters have been centered on high frequency vibration applications. Although high-frequency mechanical vibrations are more energy rich, for some situations the local ambient environmental vibrations tend to occur at lower-frequencies. For example, the highway vibration frequencies are mainly between 10 ~ 20 Hz. This paper discusses the development of a miniature vibration-to-electrical energy harvester based on electromagnetic methods using MEMS technology, targeted on the low vibration frequency regime in the 15 ~ 20 Hz range for potential use in highway structural health monitoring (HSHM) purposes or in other applications. Innovative design considerations need to be addressed to achieve this goal in a miniature package. For example, a highly pliant material and a heavy seismic mass are needed. In our design, SU-8 is chosen as a part of the composite material for the cantilever beam, micro-coil, and seismic mass fabrication. The mechanical characteristics of the energy harvester are simulated. The power generation capability of the designed energy harvester is calculated.