This PDF file contains the front matter associated with SPIE Proceedings Volume 6414, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The state estimation of a non-linear model of a piezoelectric stack actuator showing hysteresis is proposed. Model uncertainties related to hysteresis effect in piezoelectric stack actuators, most prominently in higher frequency zone; can make the closed-loop control system unstable. Furthermore it may lead to inaccurate open-loop control frequently causing harmonic distortions when the stack is driven with sinusoidal input signals. In order to solve the above issues, it is very important to determine an accurate non-linear model of the piezoelectric stack actuator. The Unscented Kalman Filter (UKF) algorithm is used to accurately estimate the states of the non-linear model of the piezo-electric stack actuator such that hysteresis effect can be accurately predicted. The states of the piezo-electric stack actuator model are assumed to be zero-mean Gaussian random variables (GRV). The UKF uses the Unscented Transformation (UT) method to choose the minimal number of samples points such that the true mean and covariance of the GRV is completely captured. On propagation through the true non-linear model of the piezo-electric stack actuator, these sample points capture the posterior mean and covariance accurately to third order for Gaussian inputs. The accurately estimated model thereby assists studies aiming at a better understanding of the hysteresis effect as well as is useful in robust control system design. Preliminary results of this investigation are presented.

Ternary Content Addressable Memory (TCAM) has been an emerging technology for fast packet forwarding, commonly used in longest prefix match routing. Large table size requirements and wider lookup table data widths have led to higher capacity TCAM designs. However, the fully parallel characteristic of TCAM makes large TCAM design more challenging and limits its capacity due to intensive power consumption. This paper proposes 3D IC technology as a solution to reduce the power consumption by reducing the interconnect capacitances of TCAM. In 3D IC, multiple wafers are stacked on top of each other, and the tiers are vertically connected through 3D vias. 3D vias reduce metal interconnect lengths and parasitic capacitances, resulting in power reduction. In this paper, 3D vias are used to replace matchlines, whose transition during parallel search operations is a major source of high power consumption in TCAM. An analysis of parasitic interconnect capacitance has been done using a quasi-static electromagnetic field simulation tool, Ansoft's Q3D Extractor, on a TCAM memory core in both conventional 2D IC structure and 3D IC structure with the process parameters of the MIT Lincoln Labs 0.18μm FDSOI process. Field analysis and spice simulation results using a capacitance model for interconnects show that a 40% matchline capacitance reduction and a 23% power reduction can be achieved by using a 3-tier 3D IC structure instead of the conventional 2D approach.

Butler matrices can be used in antenna beam-forming networks to provide a linear phase distribution across the elements of an array. The development of an 8 to 18GHz micro-strip implementation of a 4-input 4-ouput Butler matrix is described. The designed Butler matrix uses March hybrids, Schiffman phase shifters and wire-bond crossovers integrated on a single 60mm x 70mm alumina substrate.

This paper presents an optimised low-power low-phase-noise Voltage Controlled Oscillator (VCO) for Bluetooth wireless applications. The system level design issues and tradeoffs related to Direct Conversion Receiver (DCR) and Low Intermediate Frequency (IF) architecture for Bluetooth are discussed. Subsequently, for a low IF architecture, the critical VCO performance parameters are derived from system specifications. The VCO presented in the paper is optimised by implementing a novel biasing circuit that employs two current mirrors, one at the top and the other one at the bottom of the cross-coupled complementary VCO, to give the exact replica of the current in both the arms of current mirror circuit. This approach, therefore, significantly reduces the system power consumption as well as improves the system performance. Results show that, the VCO consumes only 281μW of power at 2V supply. Its phase noise performance are -115dBc/Hz, -130dBc/Hz and -141dBc/Hz at the offset frequency of 1MHz, 3MHz and 5MHz respectively. Results indicate that 31% reduction in power consumption is achieved as compared to the traditional VCO design. These characteristics make the designed VCO a better candidate for Bluetooth wireless application where power consumption is the major issue.

High speed frequency dividers are critical parts of frequency synthesisers in wireless systems. These dividers allow the output frequency from a voltage controlled oscillator to be compared with a much lower external reference frequency that is commonly used in these synthesisers. Common trade-offs in high frequency dividers are speed of division, power consumption, real estate area, and output signal dynamic range. In this paper we demonstrate the design of a high frequency, low power divider in 0.18 µm SiGe BiCMOS technology. Three dividers are presented, which are a regenerative divider, a master-slave divider, and a combination of regenerative and master-slave dividers to perform a divide-by-8 chain. The dividers are used as part of a 60 GHz frequency synthesizer. The simulation results are in agreement with measured performance of the regenerative divider. At 48 GHz the divider consumes 18 mW from a 1.8 V supply voltage. The master-slave divider operates up to 36 GHz from a very low supply voltage, 1.8 V. The divide-by-8 operates successfully from 40 GHz to 50 GHz.

In this study, strain sensors consisting of a pentacene-carbon nanotubes (CNTs) composite layer are fabricated on flexible substrates, Kapton polyimide films, employing Wheatstone bridge configuration. The sensors were characterized with bending at 45° with respect to the bridge bias direction for two different bending radii of 50, and 40mm that corresponds to strains of 1, and 1.25 %, respectively. It was noted that the output signal of the sensors is substantially enhanced with the addition of CNTs, resulting from the improvement in conductivity of the sensing active layer. This strain sensor using CNTs-organic semiconductor matrix composite as the active layer fabricated on flexible substrates is expected to possess better reliability as compared with conventional metallic foils and inorganic semiconductor strain sensors because of their low Young's modulus (~5GPa). For instance, the high Young's modulus of micro crystalline silicon (~200GPa) limits its applications for sensors when fabricated on polymeric substrates due to the large modulus mismatch between them.

Modern advances in sensor technology, digital electronics and radio frequency design have enabled the development of cheap, small, low-power sensory devices, integrating sensing, processing and communication capabilities. This work aims to present an overview of the benefits and of the most recent advances in antenna technologies, investigating the possibility of integrating enhanced solutions in a large distributed wireless sensor network for the environmental monitoring. The antenna in fact is the key element in order to fully integrate a wireless microsystemon a single chip. The integration requires a small antenna on a low-loss substratematerial compatible with the microelectronic devices. In fact, communication is usually the most energy intensive operation a node performs. Therefore, at each terminal the application of integrated and miniaturized antennas can have a significant impact, in terms of not only system performance but also cost, energy consumptions and terminal physical size. An integrated design technique of a microstrip antenna on a complex dielectric substrate is here presented. For small bit rate wireless networks, microstrip antennas are a good choice. The simplicity of realization, the low cost, the flexibility of use and the reduced dimensions make perfect for the on-chip integration. These objectives are instrumental in selecting elements that can conform to the geometry of the device. The optimization of the wireless device is also presented, to carefully adjust also parameters as the shape and dimensions of the antenna, in order to develop different layers of communication in the same device, thus endowing with multiband capabilities.

Defence Science and Technology Organisation (DSTO) is engaged in the development of sensor systems to monitor the environment and condition of high value structures and machinery. The development of this technology promises to contain escalating costs associated with the through-life support of major capital platforms, including high-rise buildings, bridges, aircraft, ships and offshore oil/gas structures. As part of this work a laser micromachining process for fabricating thin foil sensors has been developed. Laser micromachining has some inherent advantages over other processes such as metal deposition and chemical etching for the production of thin foil sensors. A chief advantage of the process is the ability to make relatively thick (100 µm) micro-patterned sensors (20 µm features) out of a very wide variety of metals with only minor changes to the process. This last feature makes feasible the manufacture of sensors out of the same material as the bulk structure that is being monitored. This paper presents results for some laser micromachined thin foil corrosion and environmental sensors and compares these with similar sensors made using different fabrication processes.

Reliable power sources are needed for portable micro-electromechanical systems (MEMS) devices such as wireless automobile tire pressure sensors. Vibration is an ubiquitous energy source that maybe 'harvested' as electrical energy at the site of the MEMS device. Existing vibration energy harvesting systems use either a piezoelectric or an electromagnetic transducer to convert vibrations into electrical energy. This electrical energy is then conditioned using a passive rectifier dc-dc converter circuit. Such vibration harvesting techniques have focused on optimising circuit efficiency and, hence, have ignored the system efficiency i.e. mechanical-to-electrical efficiency. Results obtained in the laboratory can be extrapolated to predict potential system efficiencies for MEMS vibration energy harvesting systems. Results to date, using a standard speaker as the electromagnetic transducer, have demonstrated system efficiencies of greater than 14%. Initial estimates suggest a MEMS system efficiency of more than 80% could be achieved with a high performance transducer. Research is continuing to demonstrate these higher system efficiencies with the experimental apparatus.

In this paper, an infinite IPMC cylindrical shell filled with steady-flow fluid is studied. An electric signal is applied on the electrode of IPMC, resulting in vibration of the shell-fluid coupled system. Analytical solutions are obtained by the wave propagation method for the displacement field of the cylindrical shell and the pressure in the contained liquid. The velocity field of the contained liquid due to electric potential excitation is also derived. The numerical example shows that the flow velocity can be enhanced by the applied electric potential. This model may be useful for devices using IPMC cylindrical shell structures with or without contained liquids.

This paper presents an integrated MicroPhotonic beamformer that processes RF-modulated optical signals to adaptively synthesise multiple broadband nulls in smart phased-array antennas. The beamformer is designed to operate at centre frequency of 5.6 GHz with 1 GHz bandwidth. Designs of the different photonic and RF components are presented. Simulation results show that a 4-element MicroPhotonic broadband smart antenna beamformer operating in the 5.1-6.1- GHz range can generate three broadband nulls, with less than 1.121° beam squint.

In this paper, we will investigate microwire fibers for low-loss terahertz transmission. Microwires, air-clad wire waveguides with diameter smaller than the operating wavelength (a few μm), have an enhanced evanescent field and tight wave confinement resulting in a low loss waveguide structure for the terahertz (T-ray) frequency regime. Based on our experimental data for the bulk material absorption of four glasses (F2, SF6, SF57 and Bismuth) and a polymer (PMMA), we calculate the normalized field distribution, power fraction outside the wire and effective loss. It will be shown that regardless of material, the effective loss of all microwires converges to the same order < 0.01 cm^-1.

This paper presents a short-distance reconfigurable high-speed optical interconnects architecture employing a Vertical Cavity Surface Emitting Laser (VCSEL) array, Opto-very-large-scale-integrated (Opto-VLSI) processors, and a photodetector (PD) array. The core component of the architecture is the Opto-VLSI processor which can be driven by digital phase steering and multicasting holograms that reconfigure the optical interconnects between the input and output ports. The optical interconnects architecture is experimentally demonstrated at 2.5 Gbps using high-speed 1×3 VCSEL array and 1×3 photoreceiver array in conjunction with two 1×4096 pixel Opto-VLSI processors. The minimisation of the crosstalk between the output ports is achieved by appropriately aligning the VCSEL and PD elements with respect to the Opto-VLSI processors and driving the latter with optimal steering phase holograms.

The ability of a liquid-crystal spatial light modulator (LC-SLM) to generate lens and lens arrays of variable focal lengths and selectable fields of view (FOV) makes them excellent candidates for many adaptive optics applications including free-space optical telecommunications, astronomy and retinal imaging. In this paper, we report a range of dynamic lens and lens array designs and optimization using a LC-SLM as an adaptive Hartmann-Shack wavefront sensor. The measured wavefront aberration is reconstructed using Zernike polynomials through the application of its conjugated wavefront onto the LC-SLM to achieve dynamic wavefront detection and correction. Computer algorithms based on Fourier transformation for lens synthesis have been developed to address the LC-SLM and to generate appropriate phase holograms that emulate lens and/or lenslet arrays with programmable focal lengths, tilting angles and diameters. The classic least-square (LS) method is used to determine the Zernike polynomial coefficients for the reconstruction of the aberrated wavefront. Experimental results demonstrate the dynamic generation of lens arrays of variable focal lengths. We also experimentally characterize the phase modulation performance and wavefront generation performance of the LC-SLM through the application of Zernike functions and as diffractive optical elements (DOEs) for dynamic wavefront generation.

Terahertz (THz) imaging offers many attractive advantages over existing modalities especially in its ability to obtain spectroscopic information. In particular, THz spectra are extremely sensitive to small changes of the molecular structure and different isomeric and intermolecular configurations. With a comparatively longer wavelength (0.3 mm at 1 THz), THz images suffer from the problem of low spatial resolution, as determined by Rayleigh's criterion and proves to be a major limitation. This paper reviews the existing THz near-field methods and recent developments for identifying potential areas of research.

The tunneling phenomenon assumes significant role in devices, which are put to use in information processing, data storage and transmission, digital functioning etc. The requirements call for low dimensions, low weight, low power consumption, high frequency etc. Template synthesis is an elegant approach for synthesizing nano/micro sized resonant tunneling diodes (RTDs). Using track-etch membranes as templates, we report here on the nano/micro fabrication of RTDs using binary systems like Cu-Se, Zn-Se etc and present their I-V characteristics, besides the effect of temperature and size variation of the structures.

Recently, a number of researches about linear magnetorheological(MR) damper using valve-mode characteristics of MR fluid have sufficiently undertaken, but researches about rotary MR damper using shear-mode characteristics of MR fluid are not enough. In this paper, we performed vibration control of shear-mode MR damper for unlimited rotating actuator of mobile robot. Also fuzzy logic based vibration control for shear-mode MR damper is suggested. The parameters, like scaling factor of input/output and center of the triangular membership functions associated with the different linguistic variables, are tuned by genetic algorithm. Experimental results demonstrate the effectiveness of the fuzzy-skyhook controller for vibration control of shear-mode MR damper under impact force.

Perfluorosulfonic Acid (PFSA) film, commonly used in the Polymer Electrolyte Fuel Cells (PEFC), indicates conductance of proton and permeability of H₂O. In this study a mechanical composite mover device with this PFSA and hydrogen storage alloy (HSA) thin films was made up for expecting the movement driven by volume change in the course of hydrogen migration between PFSA and HSA layers. Hydrogen storage alloy, such as LaNi₅ indicates as much as 25% of volume change in the course of H₂ absorption in gas phase. Using this characteristics, a mechanical mover device was made of PFSA film of an electrolyte polymer sandwiched by hydrogen storage alloy thin films with Au-Pd intermediate layers. The mover device was operated by migrating hydrogen ions from the PFSA layer to the HSA layer, which were generated by electrolysis of H₂O in a PFSA layer. Electrical potential was given from the outsides lead wires. All experiments were carried out in the water. We confirmed large interesting movement generated by migration of hydrogen ion by applying electric potentials.

Electro-Acoustic and Acousto-Optic communications channels have been investigated. The communications channels are intended for use by robotic agents in the Non-Destructive Evaluation (NDE) of structures containing distributed Acoustic Emission (AE) sensors. The AE sensors can be either piezoelectric or optical fibre sensors. The communications channel comprises of a piezoelectric transducer as the transmitter, an aluminium panel as the transmission medium, and either a second piezoelectric transducer or a fibre optics sensor as the receiver. The electroacoustic communications channel uses the piezoelectric transducers as the transmitter and the receiver. The acousto-optic communications channel uses a piezoelectric transducer as the transmitter, and a fibre optic sensor as the receiver. Acoustic communications represents a wireless communications method that does not require any additional hardware, as piezoelectric transducers are commonly used in the NDE of materials. Phase Shift Keying (PSK) was used for the communications encoding. Successful communications was achieved using both the piezoelectric and fibre optic receivers. The fibre optic sensor used was a Fibre Bragg Grating (FBG), and the piezoelectric transducers were Lead Zirconate Titanate (PZT) piezoceramic disc transducers. The electro-acoustic communications channel gave a data rate of 200kbps with a 1MHz square wave carrier. The acousto-optic communications channel gave a data rate of 6.3568kbps with a 635.68kHz carrier wave.

The cellulose solution dissolved in dimethylacetamide (DMAc) and LiCl was spin-coated to the silicon wafer and removed DMAc solvent using 2-propanol and deionized water. The various metal electrodes were fabricated on the DMAc-cellulose using the following several different soft lithography processes. For the first process, gold electrodes were deposited onto the polydimethylsilane (PDMS). Self-assembly monolayer (SAM) of 3-(mercaptopropyl)trimethoxysilane (MPTMS) were fabricated on the cellulose surface using vacuum deposition method before stamping the gold electrode. Since the cellulose/SAM layer method created nano-defects on the metal electrode, tetrahydrofurane (THF)/MPTMS, toluene/MPTMS, and 2-propanol/MPTMS solution method were utilized for MPTMS SAM layer fabrication. 2-Propanol/MPTMS combination exhibited minimum defects on the metal electrodes. This result may be due to the minimum diffusion of the solvent into the stamp. For the next process, gold electrodes were deposited onto the PDMS stamp, and SAM layer of MPTMS was fabricated on the gold electrodes instead of cellulose paper. This result shows that there was no defect on the metal electrode even on the nano-scale field emission scanning electron microscope (FESEM) images. Liftoff lithography with over-developing process provided high quality metal electrodes surface and edge without nano-scale defects. This modified lithography process opened the new fabrication method of various metal electrodes to the electro-active paper (EAPap).

In this paper, we report the dynamic behavior of a ferro fluid droplet in time-dependent magnetic fields. The magnetic field was generated by an array of planar coils, which were fabricated on a double-sided printed circuit board (PCB). The permanent magnetic moment of the ferro fluid droplet was created using the field of a pair of permanent magnets. The motion of the ferro fluid droplet is further aligned with the permanent magnetic field of a pair of planar coils. Two other in serial connected planar coils on the other side of the PCB displaces the droplet along a line. The direction of the droplet motion can be controlled by switching the electric current passing through them. Different paprameters affecting the motion of the ferro fluid droplet such as the droplet size, the viscosity of the surrounding medium, the electric current, and the switching frequency were investigated.

A wireless microvalve would have a wide range of applications, including biomedical applications such as fertility control and nano-litre drug delivery. Arguably the most important aspect for such a device is a secure method to actuate the valve, such that it is not actuated through the spectrum of electromagnetic radiation already present in the surrounding environment. Additionally, many of the possible applications are sensitive to electromagnetic (EM) radiation so the device should be designed to only require the minimum amount of EM input to actuate the valve. To overcome this problem, we propose the use of a coded interdigital transducer (IDT) to respond only to a coded signal. For the wireless microvalve to be useful in biomedical applications, the IDT's response to a specifically coded RF signal must be much greater than its response to another coded RF signal, even if the two codes are very similar, i.e. improve the signal ratio of the device. In this research we demonstrate a number of code sequences that have a correlation function such that the peak response is unique and can be used to provide a high signal-to-noise ratio (SNR) surface acoustic wave. That results in a unique activation of the device when the interrogating RF signal code sequence matches the stored code sequence in the device. Also we will investigate the trade-off between the needed code length to ensure secure operation and the area constrain of the device within the context of biomedical application. For this purpose, the IDT is modelled as a pulse compression filter, which correlates the input signal with a stored replica.

Structural health monitoring (SHM) technology may be applied to composite bonded repairs to enable the continuous through-life assessment of the repair's efficacy. This paper describes an SHM technique for the detection of debonding in composite bonded patches based on frequency response. The external doubler repair, commonly used to patch aircraft structures, is examined in this paper. An experimental investigation was conducted using carbon/epoxy doubler repairs bonded to carbon/epoxy substrates, with piezoelectric devices used to measure variations in the frequency response of the repaired structure due to debonding of the external doubler. Three piezoelectric devices were adhered to the structure; the actuator to the external doubler and two sensors to the parent panel. To simulate real repair design requirements (minimum surface perturbation) piezoelectric devices were installed on 'internal' surfaces. Clearance for the actuator was created by the removal of damaged material. The frequency response signature of the repaired structure with simulated debonds is analysed with respect to the response of fully bonded repairs. Results are discussed with implications for the development of a technique to monitor the integrity of external bonded repairs.

Piezoceramic (PZT) transducers are extensively used in the electromechanical impedance (EMI) based structural health monitoring (SHM) of engineering structures. In the EMI technique, the PZT transducers are generally surface bonded to the host structure and subjected to electric actuation, so as to interrogate the structure for the desired frequency range. The interrogation results in the prediction of PZT electromechanical (EM) admittance signatures, from which the mechanical impedance of the structure can be extracted. These signatures serve as indicator to predict the health/integrity of the structure, as any change in the signature is indication of crack or damage or degradation in the structure. However in real life, the structural components such as slabs, beams and columns are constantly subjected to some forms of external loading. Thus, the application of EMI technique for damage assessment of structures should take into account the influence of imposed loads since the EM admittance signature obtained for such a constantly loaded structure is different from the one obtained when damages are present in the structure. That is, the properties of the EM admittance signature obtained due to the imposed loads are different from that obtained due to damages. This paper presents an experimental investigation to show their differences. The objective is to investigate the influence of loading on the EM admittance signature. In addition, the effects of structural stiffness and EM properties of the PZT transducer on the EM admittance signature are also studied. In the experimental test, an impedance analyzer is employed to actuate the PZT transducer and simultaneously record the EM admittance signature. Different lab-sized specimens are loaded for various magnitudes of external loading. The results are expected to be useful for the non-destructive evaluation of engineering structures with imposed loads.

Most residential heating, ventilating, and air-conditioning (HVAC) systems utilize a single zone for conditioning air throughout the entire house. While inexpensive, these systems lead to wide temperature distributions and inefficient cooling due to the difference in thermal loads in different rooms. The end result is additional cost to the end user because the house is over conditioned. To reduce the total amount of energy used in a home and to increase occupant comfort there is a need for a better control system using multiple temperature zones. Typical multi-zone systems are costly and require extensive infrastructure to function. Recent advances in wireless sensor networks (WSNs) have enabled a low cost drop-in wireless vent register control system. The register control system is controlled by a master controller unit, which collects sensor data from a distributed wireless sensor network. Each sensor node samples local settings (occupancy, light, humidity and temperature) and reports the data back to the master control unit. The master control unit compiles the incoming data and then actuates the vent resisters to control the airflow throughout the house. The control system also utilizes a smart thermostat with a movable set point to enable the user to define their given comfort levels. The new system can reduce the run time of the HVAC system and thus decreasing the amount of energy used and increasing the comfort of the home occupations.

Defence Science and Technology Organisation (DSTO) has developed a low power RS485 sensor network that can be hardware configured at design time from a number of modules, depending on its final application. The core predesigned module includes network communications, microprocessor control and digital input/output. A number of analogue sensor interface modules can easily be added to this core. In addition, the software is also of modular design consisting of a set of core operating routines and a set of routines for controlling sensor operations that can be downloaded or upgraded in the field. Prime consideration in this development has been given to the need for small size, low weight, low power and versatility of operation. The hardware is based around the Texas Instruments MSP430® micro-controller. This paper will present some of the considerations leading to the design and examples of applications of the sensor network.

This report describes an open source VHDL description of a 64-bit MIPS-based processor. The pipeline can execute most instructions from the MIPS III instruction set architecture (ISA). The full pipeline is made available to digital VLSI engineers as a platform to test cell designs as a part of a complete computing system. The pipeline is an 8-stage RISC based on the MIPS R4000 series of processors, and includes common arithmetic operations on 32- and 64-bit operands, and full IEEE 754 floating point support. This report describes the architecture and components of the MIPS-based processor.

Real-time signal processing and control applications are commonly expressed in terms of matrix or vector algorithms. This paper presents a novel decoupled architecture for these algorithms. The matrix data management layer (MDML) architecture presented separates data processing from data management. It implements functions for memory sequencing and inter-processor communications that are tuned for matrix applications. This separation allows greater flexibility in the choice of data processor to find a suitable trade-off in speed, core size, power consumption and functionality.

Active Fiber Composites (AFC) possess desirable characteristics over a wide range of smart structure applications, such as vibration, shape and flow control as well as structural health monitoring. This type of material, capable of collocated actuation and sensing, can be used in smart structures with self-sensing circuits. This paper proposes four novel applications of AFC structures undergoing torsion: sensors and actuators shaped as strips and tubes; and concludes with a preliminary failure analysis. To enable this, a powerful mathematical technique, the Variational Asymptotic Method (VAM) was used to perform cross-sectional analyses of thin generally anisotropic AFC beams. The resulting closed form expressions have been utilized in the applications presented herein.

The change in extension-twist coupling due to delamination in antisymmetric laminates is experimentally measured. Experimental results are compared with the results from analytical expression existing in literature and finite element analysis. The application of the Macro-Fiber Composite (MFC) developed at the NASA Langley Research Center for sensing the delamination in the laminates is investigated. While many applications have been reported in the literature using the MFC as an actuator, here its use as a twist sensor has been studied. The real-life application envisaged is structural health monitoring of laminated composite flexbeams taking advantage of the symmetry in the structure. Apart from the defect detection under symmetric conditions, other methods of health monitoring for the same structure are reported for further validation. Results show that MFC works well as a sensor.

With the increasing development of material technology and electronic integration technology, optical fiber and its using in smart structure have become hot in the field of material research. And liquid-core optical fiber is a special kind of optical fiber, which is made using liquid material as core and polymer material as optical layer and protective covering, and it has the characteristics of large core diameter, high numerical aperture, large-scope and efficient spectrum transmission and long life for using. So the liquid-core optical fiber is very suitable for spectrum cure, ultraviolet solidification, fluorescence detection, criminal investigation and evidence obtainment, etc, and especially as light transfer element in some new structures for the measurement of some signals, such as concentration, voltage, temperature, light intensity and so on. In this paper, the novel liquid-core optical fiber is self-made, and then through the test of its light transmission performance in free state, the relation between axial micro-bend and light-intensity loss are presented. When the liquid-core optical fiber is micro-bent axially, along with the axial displacement's increase, output power of light is reducing increasingly, and approximately has linear relation to micro-displacement in a range. According to the results liquid-core fiber-optic micro-bend sensor can be designed to measure micro-displacement of the tested objects. Experimental data and analysis provide experimental basis for further application of liquid-core optical fiber.

The range of luminance levels in the natural world varies in the order of 10⁸, significantly larger than the 8-bits employed by most digital imaging systems. To overcome their limited dynamic range traditional systems rely on the fact that the dynamic range of a scene is typically much lower, and by adjusting a global gain factor (shutter speed) it is possible to acquire usable images. However in many situations 8-bits of dynamic range is insufficient, meaning potentially useful information, lying outside of the dynamic range of the device, is lost. Traditional approaches to solving this have involved using nonlinear gamma tables to compress the range, hence reducing contrast in the digitized scene, or using 16-bit imaging devices, which use more bandwidth and are incompatible with most recording media and software post-processing techniques. This paper describes an algorithm, based on biological vision, which overcomes many of these problems. The algorithm reduces the redundancy of visual information and compresses the data observed in the real world into a significantly lower bandwidth signal, better suited for traditional 8-bit image processing and display. However, most importantly, no potentially useful information is lost and the contrast of the scene is enhanced in areas of high informational content (where there are changes) and reduced in areas containing low information content (where there are no changes). Thus making higher-order tasks, such as object identification and tracking, easier as redundant information has already been removed.

This paper discusses progress in the development of a new generation of passive infrared (PIR) security sensors for the high volume military, industrial and consumer markets. Recent work on patented sensor technology is described, including the mosaic pixel focal plane array concept (MP-FPA), which enables enhanced sensor performance to be achieved with low cost optics and cheap packaging. MOEMS technology is employed for fabrication of silicon microbolometer detector arrays, which are integrated on-chip with a CMOS readout integrated circuit, and can be fabricated by large scale production methods in a silicon-based MEMS foundry. The paper addresses the application of this technology to PIR security sensors.

Traditional approaches to calculating self-motion from visual information in artificial devices have generally relied on object identification and/or correlation of image sections between successive frames. Such calculations are computationally expensive and real-time digital implementation requires powerful processors. In contrast flies arrive at essentially the same outcome, the estimation of self-motion, in a much smaller package using vastly less power. Despite the potential advantages and a few notable successes, few neuromorphic analog VLSI devices based on biological vision have been employed in practical applications to date. This paper describes a hardware implementation in aVLSI of our recently developed adaptive model for motion detection. The chip integrates motion over a linear array of local motion processors to give a single voltage output. Although the device lacks on-chip photodetectors, it includes bias circuits to use currents from external photodiodes, and we have integrated it with a ring-array of 40 photodiodes to form a visual rotation sensor. The ring configuration reduces pattern noise and combined with the pixel-wise adaptive characteristic of the underlying circuitry, permits a robust output that is proportional to image rotational velocity over a large range of speeds, and is largely independent of either mean luminance or the spatial structure of the image viewed. In principle, such devices could be used as an element of a velocity-based servo to replace or augment inertial guidance systems in applications such as mUAVs.

A case-based reasoning (CBR) knowledge base has been incorporated into a Micro-Electro-Mechanical Systems (MEMS) design tool that uses a multi-objective genetic algorithm (MOGA) to synthesize and optimize conceptual designs. CBR utilizes previously successful MEMS designs and sub-assemblies as building blocks stored in an indexed case library, which serves as the knowledge base for the synthesis process. Designs in the case library are represented in a parameterized object-oriented format, incorporating MEMS domain knowledge into the design synthesis loop as well as restrictions for the genetic operations of mutation and crossover for MOGA optimization. Reasoning tools locate cases in the design library with solved problems similar to the current design problem and suggest promising conceptual designs which have the potential to be starting design populations for a MOGA evolutionary optimization process, to further generate more MEMS designs concepts. Surface micro-machined resonators are used as an example to introduce this integrated MEMS design synthesis process. The results of testing on resonator case studies demonstrate how the combination of CBR and MOGA synthesis tools can help increase the number of optimal design concepts presented to MEMS designers.

Recently we proposed a mechanical mover device in a unimorph structure with powder hydrogen storage alloy dispersed. A silicone rubber sheet with the alloy was piled up on another pure silicone rubber sheet, then mechanical movement was generated by hydrogen gas absorption and desorption. Because the response of the movement was slow, therefore, in this research we tested the additive effect of catalyst of Pd-Al₂O₃ powder into the hydrogen storage alloy powder before mixing with rubber. The mover device with the catalyst indicated drastically modified responses, such as higher initial moving rate and also larger displacement. The results suggested the possibility of the device for medical purpose such as catheter because of a powerful but tender characteristic of the device.

Silicides have been used in CMOS technology for some years mainly to reduce sheet resistance in the source and drain regions. This paper discusses in detail the formation of nickel silicide (NiSi) and titanium silicide (TiSi₂). The composition of silicides formed using sputtered and evaporated metals are compared. Metal films (titanium or nickel) on silicon deposited by DC magnetron sputtering or electron beam evaporation were vacuum annealed to form corresponding metal silicide thin films. The problem of oxygen contamination during silicidation is also discussed. Analyses of the silicide thin films formed were carried out using Auger Electron Spectroscopy (AES) depth profiles, Atomic Force Microscopy (AFM) surface scans, and surface profilometry for measurement of feature heights. The average surface roughness of the silicide thin films is also compared, and it was observed that nickel silicide thin films were much smoother than titanium silicide thin films.

As infrared light is radiated, the CMOS Readout IC (ROIC) for the microbolometer type infrared sensor detects voltage or current when the resistance value in the bolometer sensor varies. One of the serious problems in designing the ROIC is that resistances in the bolometer and replica resistor have process variation. This means that each pixel does not have the same resistance, causing serious fixed pattern noise problems in sensor operations. In this paper, differential input stage readout architecture is suggested for bias offset reduction, noise immunity and high sensing margin. In addition, using this scheme the effects of a process variation problem and various other bias heating noise problems, are reduced. In this paper, a prototype ROICs, intended for uncooled microbolometer infrared focal plane array, is designed and fabricated. The proposed architecture is demonstrated by fabrication of a prototype consisting of 32 x 32 pixels fabricated in a 0.25-μm CMOS process.

In this paper, a reconfigurable photonic bandpass RF filter employing a semiconductor optical amplifier (SOA) and an Opto-VLSI processor is proposed where a high coherent RF modulated laser carrier is fed into the SOA and through cross-gain modulation, a low coherence RF-modulated amplified spontaneous emission (ASE) can be generated. By spectrally slicing the ASE with an optical comb filter, RF-modulated wavebands of different centre wavelengths are generated. These RF-modulated wavebands are then processed by an Opto-VLSI processor which arbitrarily shapes the intensity profile of the wavebands. A high-dispersion optical fibre introduces linear true-time delays between the different wavebands so that after photodetection a photonic bandpass RF filter with multiple taps is realised. The proof-of- concept of the photonic bandpass filter is experimentally demonstrated, and results show that the filter can operate at 3.6 GHz with more than 25 dB rejection and its working frequency can be tuned by reconfigurable holograms generated by the Opto-VLSI processor. The filter can work with the laser carrier wavelength in the range of 1523nm to 1566nm without any optical coherence noises.

In this paper, we report thin silicon shadow masks used for vacuum thermal evaporation (VTE) for manufacturing compact-size OLED (organic light emitting diodes) displays. Currently, the OLED displays attract many research attentions because of novel organic materials for emitting the light at relative low cost. The fabrication processes of OLED make use of shadow masks for thermal deposition of organic materials due to etching difficulties. The metal shadow masks are widely used because of easy access. However, the openings of the metal shadow masks are limited to vertical sidewall, which cause the rounded profile at the top surface of deposited organic layers. This may cause potential step coverage problem and non-uniform device efficiency. In order to overcome the deposition profile of organic materials, we propose to use thin silicon shadow masks. Due to the crystal orientation of (100) silicon wafers, the etched aperture slope of the silicon shadow mask has approximately 54 degree sidewalls. This slope increases the accepting angle of the openings around the edge that results in a better profile of deposited organic materials. The simulation model for deposition profile is based on basic physical equation. The simulation results show flat profile at the top surface by using silicon shadow masks with the wedged openings; which could overcome the potential problem listed above. The silicon shadow masks are fabricated by micromachining techniques and are used in the vacuum deposition of aluminum and organic polymers. The scanning electron microscopy (SEM) pictures of organic films and side profiles measured by alpha stepper will be applied to verify the simulation models and to optimize the deposition factor. We demonstrate that the thin silicon shadow masks can provide deposition advantages over traditional metal shadow masks in terms of deposition profiles of aluminum and organic layers for making OLED displays.

Actuators are finding increasing use in the various fields. And, it is one of the most important parts of machine in motion because of determine its performance. Recently, the demands for various actuators are smaller size, higher output power, lower input electrical power, and so on. To realize these demands, the key technology is processing of microfabrication. We achieved development of the three-dimensional deep X-ray lithography technique for the spiral micro coil with a high inductance. Therefore, we have fabricated and estimated the solenoidal electromagnetic type microactuator of a low driving power by using this technique. This actuator having the high aspect ratio of coil line is also expected a great force in spite of miniature size. Now, we have obtained the coil line with the width of 10 μm and the aspect ratio of 5. We have also fabricated the measurement system for suction force of electromagnetic actuator. The coil model was measured by this system, and results were relatively in good agreement with simulation results. Using this high aspect coil made by X-ray lithography technique, the electromagnetic actuators have been expected to manufacture with high output force in smaller size.

This paper presents details of a novel photoelectric system for intelligent structural health monitoring in aircrafts. Through light intensity-based experiments about loads and damages of an aircraft composite structure conducted in this paper, the potential for structural health monitoring of the composite material is discussed. Firstly, the paper demonstrates the design of a novel photoelectric system including an optical part and a circuit part. The former part consists of a light resource group and fiber optical sensors. And the latter part of this system is composed of a monitoring host and a computer, both of which work together under the instructions given by self-designed software. The schematic hardware diagram and the flow chart of the main program of the software are specified in this paper. In order to assess the monitoring effect, the loads experiments are carried out at different locations of a test object in which special optical fibers are buried. Finally, the degrees of loads and damages are measured and the experimental results are discussed. Results obtained offer feasibilities of employing the proposed photoelectric system as a monitoring device for load and damage detection in intelligent composite structures.

By introducing structure perturbation coefficients with different levels, relevant effects on PBG and density of mode (DOM) in 1D photonic crystal had been detailedly discussed under specifying numbers of bilayer and contrast of refractive index in this paper. Numerical simulation indicates that there are remarkable influences on optical properties of 1D photonic crystal resulted by structure perturbation, especially for PBG location and DOM at band edge. Generally, both PBG shifting and shrinking occurs due to disruptive periodicity. In specific case, especially along with perturbation coefficient increasing, it is found that PBG is extended obviously and the higher DOM at the band edge also can be obtained. According to this, some conclusions had been drawn which are significant to developing omnidirectional reflectors, band edge lasers and other devices based 1D photonic crystals.

Solid-state dye lasers have been developed as compact and easy-to-handle coherent light sources. In particular, distributed feedback (DFB) solid-state dye lasers are able to emit narrow-banded single-mode laser beams. In DFB lasers, the diffraction grating is a key device for selecting the laser oscillation wavelength from a fluorescent band of organic dye. We adopted an "etchless process" and fabricated gratings for DFB solid-state dye lasers quickly and at low cost. In this study, we attempted to fabricate a multi-beam DFB solid-state dye laser combining pitch-different gratings and dye-doped silica xero-gel. We succeeded at obtaining narrow-banded triple-beam laser oscillations in the same optical axis with the three-wavelength DFB solid-state dye laser device.

A moire pattern appears when two or more periodic patterns are superimposed with a small rotation angle. We focused on this phenomenon and fabricated moiré gratings by an "etchless" process. This process utilizes two-beam interference exposure with a He-Cd laser to fabricate holographic gratings quickly and at low cost. Experimental results show that the moire gratings had a diffraction efficiency sufficient to allow them to serve as resonators for DFB solid-state dye lasers. We then prepared a DFB solid-state dye laser device with moire gratings and pumped the device with a second harmonic generation (SHG) of a Nd:YAG laser. This resulted in narrow-banded DFB laser oscillation in the red wavelength region.

Ferroelectrics, which exhibit electric field dependent dielectric constant, have been of interest for possible applications on electrically controllable devices. Especially, dielectric constant of ferroelectrics could be adjusted in few microseconds to response on externally applied electric field, which made it possible ferroelectrics being used in microwave tunable devices. In this paper, Effect of BaSrTiO₂/Li₂CO₃ on low temperature sintering and BaSrTiO₂/MgO on dielectric property of thick films has been investigated for variable capacitor on RF frequency band. The thick films were fabricated by the tape casting and then the structural and dielectric properties as a function of an addition composition of plastic-sizer ratio and sintering temperature were studied. For the thick film sintered at 1100°C, it was densified to 96 % of BaSrTiO₂ theoretical density by the addition of 3 and 10 w% BaSrTiO₂/Li₂CO₃. Dielectric constant increased and tuning range increased with the increased of BaSrTiO₂/Li₂CO₃ content, which probably can be explained by the substitution of Ba³⁺, Li¹⁺ on BaTiO₃ lattice. The tunability and dielectric loss of the BaSrTiO₂/Li₂CO₃ thick film, sintered at 1150°C, were about 43 % and 0.234 at 10~15 MHz respectively. In case of BaSrTiO₂/MgO, Dielectric constant decreased and tunability increased with the added of BaSrTiO₂/MgO.

Although coordinate metrology has reached a very high state of development concerning versatility and accuracy for common engineering parts, a high precision capability with nano scale resolution and accuracy is often hard to achieve when it is required to measure very small parts and features. The limiting component is the bulky probing system of traditional coordinate measuring machines (CMMs). In order to satisfy increasing demand for highly accurate geometrical measurements on small parts and small structures, a new measuring probe of high sensitivity and small geometrical dimension with low contact forces needs to be developed. In this paper, a probing system, which combines a Fibre Bragg grating (FBG) embedded optical fibre tactile probe with an optical sensing technique, has been used. A novel simple wavelength shift demodulation system is tested which incorporates using the single mode light launched from a laser diode (LD) forming an external cavity between the LD and the FBG sensor to detect the Bragg wavelength shift induced by the strain on the FBG sensor. This demodulation method can be used to detect the strain-induced wavelength shift of the FBG. A strain resolution of 0.6 με is achieved. With the sensor elements integrated into the probe tip directly, the system sensitivity can be increased significantly.

A template-free, rapidly-mixed reaction was employed to synthesize polyaniline nanofibers using chemical oxidative polymerization of aniline. Camphor sulfonic acid (CSA) was used in the synthesis to obtain 50 nm average diameter polyaniline nanofibers. The nanofibers were deposited onto a 64^o YX LiNbO₃ SAW transducer. The sensor was tested towards hydrogen (H₂) gas while operating at room temperature. A fast response and recovery with high sensitivity and good repeatability were observed.

Accurate characterisation of transmission lines is essential in enabling the design of Monolithic Microwave Integrated Circuits (MMICs) or Radio Frequency Integrated Circuits (RFICs). One RFIC technology currently being pursued is Silicon on Sapphire Complementary Metal Oxide Semiconductor (CMOS) technology. CMOS processes typically involve stacked metal layer structures and the correct method of modelling coplanar waveguides in CMOS is unclear. This paper reports on preliminary studies into electromagnetic design, with an emphasis on correctly predicting losses associated with these structures.

A small low-cost motion detector would have widespread applications in visual control systems such as miniature unmanned aerial vehicles and collision avoidance systems. In the last 20 years a number of analog VLSI chips have been developed which incorporate both photodetection and motion computation on the same chip. Nevertheless, artificial real-time vision and simple seeing systems remain a massive challenge mainly because the environment greatly impacts on their performance. On the other hand, biological systems have, through years of evolution, come up with a number of simple but clever solutions. The Reichardt Correlator is a biologically inspired model for motion detection. However, the basic model is not a robust estimator of velocity. The accuracy and reliability of this model can be significantly improved through various elaborations. VLSI is ideally suited to the parallel processing seen in nature because it allows for high device integration density and complex implementation of complex functions. Howsoever, VLSI poses some serious bounds on the types of elaborations that can be implemented. We have explored this problem and will present a number of improved models with robust outputs that are practical in terms of real time implementation in microchips.

The response resolution of the stacked gradient homojunction vertical single junction photodiode can be improved further by including a laterally stacked gradient homojunction in the form of inter-pixel nested ridges that extend from each epilayer towards the frontwall of the photodiode (Fig 4). In this study, we have simulated the effect of inter-pixel ridge height and width on the response resolution of a two dimensional CMOS compatible stacked gradient homojunction photodiode array. The results demonstrate enhanced relative crosstalk suppression and slightly enhanced maximum quantum efficiency compared to all photodiodes previously simulated by the authors, except for the double junction photodiode which demonstrated better crosstalk suppression though being much reduced in sensitivity. As inter-pixel nesting of ridges increases with increase in ridge height, the relative crosstalk reduces and the maximum quantum efficiency is improved to a constant level above that of the conventional stacked gradient homojunction photodiode. As the lateral gap between nested ridges increases and the ridges' widths reduce more rapidly through the underlying epilayers, the relative crosstalk deceases while the maximum quantum efficiency remains constant. Frontwall illumination is advantaged in reduced crosstalk due to the immediacy of illumination to the depletion region and being far from the substrate. Backwall illumination is superior in sensitivity due to more carriers being photogenerated outside the well and being focused into the depletion region by the two minority carrier mirrors.

Terahertz (THz) radiation has many far reaching applications - of specific interest is that many non-metallic and non-polar substances are transparent in the THz frequency range. This provides many practical uses for security purposes, where it is possible to detect and determine various substances that may be hidden or undetectable via conventional methods such as X-rays. In addition to this property, terahertz radiation can either be used in reflection or transmission modes. This paper will look into the use of transmission techniques to detect various substances using a terahertz system. Common materials used in bags and suitcases such as nylon, polycarbonate (PC), and polyethylene (PE) are tested for transparency. These materials then sandwich various illicit substances, and are scanned by the terahertz system to obtain spectral data, simulating the probing of a suitcase. The sample materials are then subtracted from the obtained data, which is then compared with previously obtained data of known substances, and an examination of features in the sample is carried out to determine if a particular substance is present in the sample.

We fabricated an infrared wire-grid polarizer that was made of a tungsten silicide (WSi) grating on a Si substrate. The photolithography by the use of the two-beam interference was conducted for generating the short-period grating structure. This photoresist pattern was used as a mask for the reactive ion etching of the WSi coating and the Si substrate. Consequently, we could fabricate the WSi/Si grating with 400-nm period and 550-nm depth that acted as a wire-grid polarizer. The transmittance of TM polarization was 58% at 4-μm wavelength, which exceeded the theoretical transmittance of Si (54%). This enhancement of the transmittance was caused by the reduction in the reflectance due to the subwavelength-grating structure. The extinction ratio at 2.7-μm wavelength was 20 dB. We also measured the extinction coefficient κ of WSi, and verified that WSi was a suitable polarizing material in the mid-infrared range.

This paper presents the design and implementation of an optimised MEMS-based reconfigurable VCO for a multi-standard mobile terminal for GSM900, DCS1800 and WCDMA standards. In this VCO design, the passive components, including inductors, capacitors and switches are replaced by MEMS components, to improve the system performance and reduce the system power consumption. Moreover, a phase noise optimisation algorithm is also proposed to optimise the VCO design for optimum system phase noise and minimum power consumption. Results show that a 50% reduction of power consumption is achieved when the MEMS components are used instead of the passive components. A 31% further reduction of power consumption is also achieved when the tail-current optimisation algorithm is applied. This characteristic makes the VCO a better candidate for wireless communication applications where power consumption is the major factor.