This PDF file contains the front matter associated with SPIE Proceedings Volume 7291, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing

In a time when homemade explosive devices are being used against soldiers and in the homeland security environment, it is becoming increasingly evident that there is an urgent need for high-tech chemical sensor packages to be mounted aboard ground and air vehicles to aid soldiers in determining the location of explosive devices and the origin of bio-chemical warfare agents associated with terrorist activities from a safe distance. Current technologies utilize relatively large handheld detection systems that are housed on sizeable robotic vehicles. Research and development efforts are underway at the Army Aviation & Missile Research, Development, and Engineering Center (AMRDEC) to develop novel and less expensive nano-based chemical sensors for detecting explosives and chemical agents used against the soldier. More specifically, an array of chemical sensors integrated with an electronics control module on a flexible substrate that can conform to and be surface-mounted to manned or unmanned vehicles to detect harmful species from bio-chemical warfare and other explosive devices is being developed. The sensor system under development is a voltammetry-based sensor system capable of aiding in the detection of any chemical agent and in the optimization of sensor microarray geometry to provide nonlinear Fourier algorithms to characterize target area background (e.g., footprint areas). The status of the research project is reviewed in this paper. Critical technical challenges associated with achieving system cost, size, and performance requirements are discussed. The results obtained from field tests using an unmanned remote controlled vehicle that houses a CO₂/chemical sensor, which detects harmful chemical agents and wirelessly transmits warning signals back to the warfighter, are presented. Finally, the technical barriers associated with employing the sensor array system aboard small air vehicles will be discussed.

Tubular nanomaterials possess hollow structures as well as high aspect ratios. In addition to their unique physical and chemical properties induced by their nanoscale dimensions, their inner voids and outer surfaces make them ideal candidates for a number of biomedical applications. In this work, three types of tubular nanomaterials including carbon nanotubes, hematite nanotubes, and maghemite nanotubes, were synthesized by different chemical techniques. Their structural and crystalline properties were characterized. For potential bioapplications of tubular nanomaterials, experimental investigations were carried out to demonstrate the feasibility of using carbon nanotubes, hematite nanotubes, and maghemite nanotubes in glucose sensing, neuronal growth, and drug delivery, respectively. Preliminary results show the promise of tubular nanomaterials in future biomedical applications.

Nanometer-sized particles have novel optical, electronic, magnetic or structural properties and are currently under intense development for application in cancer, cardiovascular diseases, and degenerative neurological disorders such as alzheimer's disease. Targeted nanoparticle drugs offer significant advantages in improving cancer therapeutic efficacy and simultaneously reducing drug toxicity. We report here the synthesis, characterization and toxicity test of FeCo and Eu: Gd₂O₃ nanoparticles. Chemical routes, such ad coprecipitation and sol-gel techniques were used for the synthesis of the nanoparticles, and the surface of the nanoparticles was coated with silica. Structural and microstructural studies reveal that both type of nanoparticles 20 nm in size with very narrow size distribution. These nanoparticles demonstrate strong magnetic and optical properties at room temperature. Toxicity test shows that FeCo nanoparticles are very toxic, however toxicity decreases when the nanoparticles were coated with a thin layer of silica. However toxicity decreases when the nanoparticles were coated with a thin layer of silica. However, both uncoated and coated Eu:Gd₂O₃ nanoparticles show significantly reduced toxicity. Our results suggest that these nanoparticles are useful for biomedical applications. The detail of the results will be presented.

Wireless Nanosensors and Systems research project has been investigating a systems approach to designing sensors systems. The effort is multifaceted and ranges from the design of low-cost sensors for various applications, such as biomedical or structural health monitoring, to the design of wireless interfaces and protocols with suitable networking and design of protocols to transmit sensor data from one place to another securely and to the design of appropriate applications themselves. The research team has been developing a system-engineering framework that forms the basis for collaborative activities across three campuses, University of Arkansas at Fayetteville, University of Arkansas at Little Rock and Arkansas State University, that captures the relationship between sensors, wireless interfaces, the network, the testbed that facilitates applications-level communications.

The emerging field of nanotechnology offers the development of new materials and methods for crucial neuroscience applications namely (a) promoting survival and growth of the neurons, and (b) monitoring physiological signals generated in the nervous system such as excitation, synaptic transmission, release of neurotransmitter molecules and cell-to-cell communication. Such bio-devices will have several novel applications in basic science, laboratory analysis and therapeutic treatments. Our goals in this field of research include (a) development of new biocompatible substrates to guide and promote neuronal growth along specific pathways; (b) designing a neuron-friendly, bio-molecule delivery system for neuroprotection; (c) monitoring of electrical activity from neuron and also from neuronal networks; (d) determining the diffusion and intracellular localization of nanomaterial interacting with neurons at high resolution; and (e) detection of release of neurotransmitter molecules by means of newly designed nanosensors. Here we describe the fabrication and use of magnetic nanotubes and nanowire electrode arrays in studies using a cell culture model of neuronally differentiating rat pheochromocytoma (PC 12) cells. The magnetic nanotubes were fabricated by a template method yielding hematite (α-Fe₂O₃) nanotubes. These nanotubes were coupled with nerve growth factor (NGF). Vertically aligned nanowires were fabricated on glass substrates using the lithography-assisted template bonding (LATB) method. Rat pheochromocytoma (PC12) cells were cultured on these nanotubes and polylysine coated nanowire electrodes. Our results showed that magnetic nanotube bound NGF was available to PC12 cells as they showed significant differentiation into neurons. PC12 cells growing on nanowires in the presence of NGF differentiated into neurons capable of synthesis and release of dopamine upon stimulation. The neurons grew healthy neurites appearing to form synapses with other neurons in the dish. These results show that the magnetic nanotubes were capable of delivering neurotrophic molecules and the nanowire electrodes are neuron-friendly, promote cell to cell communication and can be used as bio-sensors in the nervous system.

Magnetic nanomaterials, especially nanoparticles and nanotubes, are among the most widely used nanomaterials for biomedical applications, and they are also the most promising nanomaterials for clinical treatments. This paper starts with the fundamentals for nanomedicine and magnetic nanomedicine. After discussing the basic requirements for the biomedical applications, the properties and the biomedical applications of magnetic nanoparticles and nanotubes are discussed. Our results indicate that, with suitable functionalization, iron oxide nanomaterials are non-toxic to biological systems, and they are ideal drug carriers which can be remotely controlled by external magnetic fields. At the final part of this paper, the challenges and our approach for targeted drug delivery with controlled release are discussed.

According to a report by the American Heart Association, there are approximately 3-4 million Americans that may experience silent Myocardial Ischemia (MI). Silent MI is a serious heart condition that can progress to a severe heart attack without any warning and the consequences of such an event can turn fatal quickly. Therefore, there is a strong need for a sensor that can continuously monitor the onset of the condition to prevent high risk individuals from deadly heart attacks. An increase in extracellular potassium levels is the first sign of MI and timely sensing with an implantable potassium sensing biosensor could play a critical role in detecting and expediting care. There are challenges in the development of an implantable potassium sensing electrode one of which includes signal drift. The incorporation of novel nanostructures and smarter materials hold the potential to combat these problems. This paper presents a unique design for an all-solid-state potassium sensing device which offers miniaturization along with enhanced signal transduction. These characteristics are important when it comes to implantable devices and signal drift. Sensor design details along with fabrication processes and sensing results are discussed.

This research discusses the development of biosensors with vertically aligned nanowires, and the evaluation of their physical properties, electrochemical performance and biocompatibility. The developments include neurotransmitter (dopamine) sensors, glucose sensors for continuous monitoring, potassium ion sensors and integration of those sensors. A hemi-cylindrical nanocavity structure has been developed for dopamine sensing using redox cycling with radial diffusion within the cavities. By immobilization of enzymes in a conducting polymer matrix on vertically aligned nanowires, glucose sensing electrodes have been obtained with high sensitivity and selectivity. In addition, potassium sensing, potentially useful for monitoring changes of extracellular potassium concentration during myocardial ischemia, has been demonstrated using ion selective membranes (ISM) on nanowires. Sensor developments and measurement results are included in the presentation along with descriptions of top-down and bottom-up nano-/micro-fabrication technologies such as lithography and thin film deposition.

MEMS technology could be an option for the development of a pressure sensor which allows the monitoring of several electronic signals in humans. In this work, a comparison is made between the typical elasticity curves of several arteries in the human body and the elasticity obtained for MEMS silicon microstructures such as membranes and cantilevers employing Finite Element analysis tools. The purpose is to identify which types of microstructures are mechanically compatible with human arteries. The goal is to integrate a blood pressure sensor which can be implanted in proximity with an artery. The expected benefits for this type of sensor are mainly to reduce the problems associated with the use of bulk devices through the day and during several days. Such a sensor could give precise blood pressure readings in a continuous or periodic form, i.e. information that is especially important for some critical cases of hypertension patients.

Phospholipid molecules are the fundamental building blocks of cell membranes in living organisms. These molecules are amphipathic with two hydrophobic fatty acid chains (tails) linked to a phosphate containing hydrophilic group (head) that can spontaneously form a bilayer lipid membrane (BLM) with a 6-10 nm thickness in water. BLMs have been classified using some porous synthetic substrate for support. Droplet interface bilayers (DIB) have allowed researchers to study BLMs formed without the use of a porous synthetic substrate. The DIBs are formed at the interface of water droplets and a non-polar solvent. The phospholipids will form a monolayer around the water droplets and when two droplets are brought into contact with each other, a single bilayer will form. DIBs have been used to form networks of BLMs that can be used for multiple purposes. The exact size of the BLM between two droplets is inferred from electrical measurements. The two droplets can be connected through a pore in a synthetic substrate of known dimensions that can limit the area of the BLM. This paper will present the results of forming a BLM on a synthetic substrate by using the DIB method of formation.

A fabrication process and multi project wafer run (MPW) service has been developed for realizing integrated passive devices. The fabrication process is simple and low cost ranging applications from consumer electronics to instrumentation and measurement as well as defense and scientific applications. The fabrication process is offered as an MPW service for all types of organizations being suitable for scientific experiments, product prototyping or optimization. The technology has used for realizing microwave and millimeter wave components. Measured result show that the technology as well as accurate design result in loss less than 1.1 dB at 60 GHz for an integrated band-pass filter.

The design of nanosensor networks and systems encompass multiple areas of research, which include: Design of nanosensors and modeling; Design of wireless interfaces; Design of reliable sensor networks that sense and collect data reliably; Design of backbone networks capable of reliably transporting collected data to remote servers; Design of secure servers for data transfer. This paper provides a systems engineering framework and provides insights into the above design issues.

Potassium ion monitoring, in human body, is important for diagnostic and therapeutic purposes. The dynamic response of potassium selective ISFET sensors is instrumental in formulating calibration schema and signal compensations to correct systematic errors. In the research reported here, response characteristics of potassium selective ISFETs were studied. The range of detection was set between 1mM and 25mM to cover all the physiological potassium concentrations. The signals were obtained from an array of sensors, with different aspect ratios, by varying potassium ion concentrations in a time dependent fashion. Normalization of the drain current was used to compensation for variance in order of magnitude observed in different sensors. Sensor response time and linear response range were analyzed, in relation to difference in aspect ratios. Probable modifications in calibration scheme and compensation technique, subjective to the findings, have been suggested.

In this work, a current transport model for the carbon nanotube field effect transistor has been built, which includes both static and dynamic behavior. A model of carbon nanotube as an interconnection in integrated circuits has also been presented, which is based on quasi one-dimensional fluid theory and combined with the current transport model of carbon nanotube field effect transistors to study the performance of carbon nanotube based integrated circuits. Verilog- AMS in combination with Cadence/Spectre has been used in characterizing carbon nanotube field effect transistors and all carbon nanotube based integrated circuits. It is shown through thionyl chloride and DNA detection at molecular levels that the transient behavior of carbon nanotube based circuits can be used for bio- and chemical sensing applications.

The surface of directly coated TiO₂ nanoparticles on the Al-electrode has many nanoscale holes and cracks. The defects of the TiO₂ layers can be removed via coating PEDOT:PSS on top of the TiO₂ layer. Schottky diodes having various thicknesses of the TiO₂ layers and PEDOT:PSS layers were fabricated. The normalized forward current densities were almost the same for the Schottky diodes fabricated with various thicknesses of the TiO₂ layers. The current densities of the Schottky diodes with double coatings have large deviation. The log(J) vs. log(V) and shows nonlinear J-V characteristics representing the multiple electron emission mechanisms such as space-charge limited conduction, Poole- Frenkel emission, or thermoionic emission. The plots of log(J) vs. E^1/2 and log(J/E) vs. E^1/2 show nonlinear behavior and with two distinctive slopes. Based on these results, the electron emission mechanism may have two distinctive mechanisms including Schottky emission mechanism and Poole-Frenkel emission mechanism.

NASA Langley Research Center has developed several breakthrough materials technologies using bio and nanotechnology specifically for device applications. With their expertise and strength in device-specific materials technologies, Langley researchers have identified innovative methods and newly designed materials, such as rhombohedral single crystal silicon-germanium, twin-lattice structures of silicon-germanium for thermoelectric applications, smart optical materials, and size-controlled metallic nanoparticles. These new materials have offered new opportunities to develop devices and power systems, such as micro spectrometers, quantum-apertures, wireless power transmission systems, smart optics, bionanobatteries, and biofuel cells. An overview of these technologies will be given at the meeting.

Sample transport is an important requirement for In-situ analysis of samples in NASA planetary exploration missions. Tests have shown that powders or liquid drops on a surface can be transported by surface acoustic waves (SAW) that are generated on the surface using interdigital transducers. The phenomena were investigated experimentally and to generate SAWs interdigital electrodes were deposited on wafers of 128° rotated Y-cut LiNbO₃. Transporting capability of the SAW device was tested using particles of various sizes and drops of various viscosities liquids. Because of different interaction mechanisms with the SAWs, the powders and the liquid drops were observed to move in opposite directions. In the preliminary tests, a speed of 180 mm/s was achieved for powder transportation. The detailed experimental setup and results are presented in this paper. The transporting mechanism can potentially be applied to miniaturize sample analysis system or "lab-on-chip" devices.

Sensor arrays for bio/chemical sensing generally incorporate different types of sensors with different substrate coatings, enabling increased sensor sensitivity and selectivity. However, a challenge in using multiple sensor systems is integration with RF electronic circuitry. This work presents the development of flexural plate wave (FPW) acoustic devices implemented in a sensor array and co-integrated on a Si-CMOS circuit. FPWs are highly sensitive to surface perturbations and indirectly sense analytes by detecting mass changes on the sensing plate surface. The sensors are placed in an oscillating circuit, where changes in the oscillation frequency are used to determine changes in the wave velocity due to mass loading by the analyte [1, 2]. Since FPWs are generated in thin plates, these devices are highly sensitive to loading and exhibit the highest mass sensitivities of any acoustic wave device [1, 2]. In the work presented, FPWs are fabricated on Si/SiO₂/Si native substrates, with the interdigitated transducers (IDTs) isolated from the active sensing surface. This innovative design enables the sensors to be fabricated and then separated from the native substrate, transferred, and bonded to the host Si-CMOS circuit. Thus, a new approach for the heterogeneous integration of FPW sensors and circuitry is provided. Following integration, the FPWs can be customized with either chemical membranes or biological functionalization. Moreover, this novel approach allows each sensor to be optimized independently before being connected to the host substrate. This paper presents the design, development, and integration process of an FPW sensor on Si-CMOS circuitry.

Cobalt and iron nanoparticles are doped in carbon nanotube (CNT)/polymer matrix composites and studied for strain and magnetic field sensing properties. Characterization of these samples is done for various volume fractions of each constituent (Co and Fe nanoparticles and CNTs) and also for cases when only either of the metallic components is present. The relation between the magnetic field and polarization-induced strain are exploited. The electronic bandgap change in the CNTs is obtained by a simplified tight-binding formulation in terms of strain and magnetic field. A nonlinear constitutive model of glassy polymer is employed to account for (1) electric bias field dependent softening/hardening (2) CNT orientations as a statistical ensemble and (3) CNT volume fraction. An effective medium theory is then employed where the CNTs and nanoparticles are treated as inclusions. The intensity of the applied magnetic field is read indirectly as the change in resistance of the sample. Very small magnetic fields can be detected using this technique since the resistance is highly sensitive to strain. Its sensitivity due to the CNT volume fraction is also discussed. The advantage of this sensor lies in the fact that it can be molded into desirable shape and can be used in fabrication of embedded sensors where the material can detect external magnetic fields on its own. Besides, the stress-controlled hysteresis of the sample can be used in designing memory devices. These composites have potential for use in magnetic encoders, which are made of a magnetic field sensor and a barcode.

Surgeons in various medical areas (orthopedic surgery, neurosurgery, dentistry etc.) are using motor-driven drilling tools to make perforations in hard tissues (bone, enamel, dentine, cementum etc.) When the penetration requires very precise angles and accurate alignment with respect to different targets, precision cannot be obtained by using visual estimation and hand-held tools. Robots have been designed to allow for very accurate relative positioning of the patient and the surgical tools, and in certain classes of applications the location of bone target and inclination of the surgical tool can be accurately specified with respect to an inertial frame of reference. However, patient positioning errors as well as position changes during surgery can jeopardize the precision of the operation, and drilling parameters have to be dynamically adjusted. In this paper the authors present a quantitative method to evaluate the corrected position and inclination of the drilling tool, to account for translational and rotational errors in displaced target position. The compensation algorithm applies principles of inverse kinematics wherein a faulty axis in space caused by the translational and rotational errors of the target position is identified with an imaginary true axis in space by enforcing identity through a modified trajectory. In the absence of any specific application, this algorithm is verified on Solid Works, a commercial CAD tool and found to be correct. An example problem given at the end vindicates this statement.

Various conbinations of TiO₂ sol-gel were prepared to fabricate Schottky diodes. Pure TiO₂ sol-gel was spin-coated to the various substrates such as glass, silicon wafer, and cellulose. The sol-gel driven TiO₂ films were generated cracks all over the surface during the annealing process. To prevent cracks, polyethylene glycol (PEG) was added to TiO₂ sol-gel solution. TiO₂-PEG sol-gel was spin-coated to the substrate and heat treated at 100, 200, and 300°C for 1 h. The film thicknesses were 230, 190, and 129 nm for the sample heated at 100, 200, and 300°C, respectively, and no cracks were observed. The FTIR pesk at 3380 cm^-1 corresponds to -OH stretching mode and disappeared as the heating temperature increased. The characteristic peaks of PEG at 2875 and 1120 cm^-1 also disappeared as the heating temperature increased. The Schottky diodes comprised of Al/PEG-TiO₂/Au with various heat treatment were fabricated. The forward current was drastically increased as the annealing temperature increased. The plots of parabolic conduction curves based on Schottky conduction model, Poole-Frenkel conduction model, and space charge limitted conduction model show nonlinear relationship. These nonlinear relationship indicates that the conduction mechanism is not purely single conduction mechanism.

A polymeric SU8 rib waveguide Bragg grating filterfabricated using reactive ion etching (RIE) and solvent assisted microcontact molding (SAMIM) is presented. SAMIM is one kind of soft lithography. The technique is unique in which that a composite hPDMS/PDMS stamp was used to transfer the grating pattern onto an inverted SU8 rib waveguide system. The composite grating stamp can be used repeatedly several times with degradation. Using this stamp and inverter rib waveguide structure, the Bragg grating filter fabrication can be significantly simplified.

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. 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. In this paper these electrical signals are modeled through a nano/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. The simulated circuit can be easily be modified by adding some more ionic channels and the results can be used to predict necessary external stimulus needed for stimulation of neurons affected by the Parkinson's disease (PD). Implementing such a model in PD patients could predict the necessary voltages required for the electrical stimulation of the sub-thalamus region for the control tremor motion.

Bacterial cellulose and chitosan blends have been successfully prepared by immersing wet bacterial cellulose pellicle in chitosan solution followed by freeze-drying. By changing chitosan concentration and immersion time, the chitosan content in the blends is ranged from 12% to 45%. The products look like a foam structure. SEM images show that chitosan molecules can penetrate into bacterial cellulose forming multilayer structure. The foam has very well interconnected porous network structure and large aspect surface. By incorporation of chitosan in bacterial cellulose, XRD patterns indicate that crystalline structure does not change but crystallinity decreases from 82% to 61% with chitosan content increasing from 12% to 45%. According to TGA results, the thermal stability has been improved. At the same time, the mechanical properties of bacterial cellulose and chitosan blends are good enough for potential biomedical application such as tissue engineering scaffold and would dressing material.

The possibility as a vibration sensor of Electro-Active paper (EAPap) based on piezoelectricity was investigated in the present paper. The EAPap was fabricated by regenerating and tape casting cellulose. The sample was coated by thin laminating film for packaging. The capacitance of EAPap was measured and compared with commercial PVDF. Relative permittivity of EAPap was 12, which was same as commercially available PVDF. This reveals that EAPap has similar sensing potential of synthetic piezo polymer film. The simple aluminum cantilevered beam was used for the vibration testing and EAPap was attached on the beam. The original EAPap sensor without grounding and shielding has greatly affected by the surrounding noise such as power noise especially. The power noise reduced dramatically with grounding and shielding of EAPap. The impulsive response of EAPap provided correct dynamic characteristics of the beam. Especially, twisting mode of the beam was clearly observed even though the EAPap was attached at the center of the beam. This is because the sensing capability of EAPap is based on piezoelectricity which is bidirectional strain characteristics. EAPap sensor based on piezoelectricity provided a great potential as a vibration sensor.

Novel smart materials have been suggested for various sensor applications such as chemical sensor, bio sensor, wireless communication, and radio frequency identification (RF-ID) devices. It was reported that bio-compatible and as well as bio-degradable, naturally abundant, and flexible piezoelectric cellulose electro-active paper (EAPap) had a great industrial potential due to its piezoelectricity. Here we studied the feasibility of surface acoustic wave (SAW) devices using thin piezoelectric cellulose EAPap. The single inter-digit transducer (IDT) pattern with 10 μm finger width was designed and fabricated on thin piezoelectric EAPap using lift-off technique. The frequency response to different vapor dose of isopropyl alcohol under will be presented.

We studied the wireless power transmission capabilities of microwave through human skin-tissue. Microwave transmission through simulated human skins was tested with rectenna array as a power receiver located under the simulated human skin tissue. Most of transplanted medical devices and sensors require power to operate autonomously but currently by imbedded battery. Wireless power transmission alleviates the needs of imbedded power source and hard-wire power network. We used human skin-like materials, such as various polyurethanes and pork skin, under X-band microwave exposure. Transmission rate through various polyurethanes under the threshold limit value (TLV) and dielectric constant was measured in this experiment. It is also critical to measure specific absorption rates (SAR) of polyurethanes and transmission rates through polyurethanes as well as pork skin. This paper presents power transmission rates under varying thickness of polyurethanes, and effectiveness and efficiency of rectennas under the TLV of microwave power. In addition, we will discuss milimeter wave thermograph and hazards the absorption characteristics of human skin under 8-13 GHz using the results of polyurethanes and pork skin.

Peer-to-Peer (P2P) networks have been used efficiently as building blocks as overlay networks for large-scale distributed network applications with Internet Protocol (IP) based bottom layer networks. With large scale Wireless Sensor Networks (WSNs) becoming increasingly realistic, it is important to overlay networks with WSNs in the bottom layer. The suitable mathematical (stochastic) model that can model the overlay network over WSNs is Queuing Networks with Multi-Class customers. In this paper, we discuss how these mathematical network models can be simulated using the object oriented simulation package OMNeT++. We discuss the Graphical User Interface (GUI) which is developed to accept the input parameter files and execute the simulation using this interface. We compare the simulation results with analytical formulas available in the literature for these mathematical models.

Ferroelectrics in microwave antenna systems offer benefits of electronic tunability, compact size and light weight, speed of operation, high power-handling, low dc power consumption, and potential for low loss and cost. Ferroelectrics allow for the tuning of microwave devices by virtue of the nonlinear dependence of their dielectric permittivity on an applied electric field. Experiments on the field-polarization dependence of ferroelectric thin films show variation in dielectric permittivity of up to 50%. This is in contrast to the conventional dielectric materials used in electrical devices which have a relatively constant permittivity, indicative of the linear field-polarization curve. Ferroelectrics, with their variable dielectric constant introduce greater flexibility in correction and control of beam shapes and beam direction of antenna structures. The motivation behind this research is applying ferroelectrics to mechanical load bearing antenna structures, but in order to develop such structures, we need to understand not just the field-permittivity dependence, but also the coupled electro-thermo-mechanical behavior of ferroelectrics. In this paper, two models are discussed: a nonlinear phenomenological model relating the applied fields, strains and temperature to the dielectric permittivity based on the Devonshire thermodynamic framework, and a phenomenological model relating applied fields and temperature to the dielectric loss tangent. The models attempt to integrate the observed field-permittivity, strain-permittivity and temperature-permittivity behavior into one single unified model and extend the resulting model to better fit experimental data. Promising matches with experimental data are obtained. These relations, coupled with the expression for operating frequency vs. the permittivity are then used to understand the bias field vs. frequency behavior of the antenna. Finally, the effect of the macroscopic variables on the antenna radiation efficiency is discussed.

Many types of wireless modules are being developed to enhance wireless performance with low power consumption, compact size, high data rates, and wide range coverage. However trade-offs must be taken into consideration in order to satisfy all aspects of wireless performance. For example, in order to increase the data rate and wide range coverage, power consumption should be sacrificed. To overcome these drawbacks, the paper presents a wireless client module which offers low power consumption along with a wireless receiver module that has the strength to provide high data rates and wide range coverage. Adopting Zigbee protocol in the wireless client module, the power consumption performance is enhanced so that it plays a part of the mobile device. On the other hand, the wireless receiver module, as adopting Zigbee and Wi-Fi protocol, provides high data rate, wide range coverage, and easy connection to the existing Internet network so that it plays a part of the portable device. This module demonstrates monitoring of gait analysis. The results show that the sensing data being measured can be monitored in any remote place with access to the Internet network.

We introduce a novel method for low substrate temperature carbon nanotube (CNT) deposition utilizing photo-chemical vapor deposition (PCVD). Aluminum and nickel catalyst layers are deposited on thermally oxidized silicon substrates for CNT growth. The catalyst layers of varying thicknesses are deposited by electron beam evaporation. Different catalyst annealing temperatures and pressures are investigated. The CNT deposition is carried out immediately following the annealing process. The presence of light source during CNT deposition assists in fragmentation of the CCl₄ precursor molecules used, thereby permitting a lower substrate temperature during growth. We have successfully deposited CNTs at substrate temperatures as low as 400 °C by this technique.