Ferroelectric thin film is the target of the interest in micro electromechanical system, memory etc. Smart MEMS is to be developed with such smart materials thin films. In spite of the success in commercialization of FRAM application, MEMS application is still under R&D state. Despite to their promising properties, there are only few reports on the use of such layers as MEMS devices. Problems for application are mainly caused by the necessary very small dimension of such devices, in contrast to limitations and tolerances of the used micro-technologies. Although deposition of piezoelectric PZTlayer using different thin-film technologies has reached an advanced state, the layers of more than 1 micron thickness needed for MEMS applications is still difficult to deposit. To deal with these problems, the structure or the function of the devices has to be coped with such technologically caused constraints, like thickness deviation and deformation by residual stress, as well as optimization of materials processing parameters. As an application of the thin films, Piezoelectric SFM and scanning mirror device are designed and fabricated as examples of the target MEMS devices with special emphases placed on materials, processing and device structure optimization. Sol gel deposited as well as Pulsed Laser Ablation Deposited PZT layers have been developed and applied for the devices. To compensate the deformation of the devices, bimorph PZT actuator is also presented. A piezoelectric SPM is expected to provide a promising answer to High density data storage devices, as the piezoelectric layer serves as a actuator for the cantilever as well as a force sensor. This paper describes a novel probe arrays integrated with micro-heaters for the AFM thermal mechanical data storage. The probes have cantilevers 3um thick, 100-200um long, and 30-70um wide, and have micro-heater integrated on the triangle end of the cantilever. The cantilever consists of a piezoelectric layer on a silicon base for the heater actuation and force sensing. The Lead-Titanate-Zirconate (PZT) is selected as the piezoelectric material for its high piezoelectric coefficients comparing to crystal materials (for example, ZnO2). We design the heater on the triangle end of the cantilever, and shape the apex part as the narrowest to get the biggest power dissipation. The prototype of the device has been fabricated and characterized.

Control of the sound reflection from an underwater object is a very important issue. Active piezoelectric layers properly coated on the external surface of the object can control the reflection of incident sound waves. In many active control systems, a sensing device must be employed for the detection of the incident sound. The detected signal is then fed to properly controlled actuators to produce a sound wave to cancel the sound reflection. Multi-layered active coatings are therefore employed, which includes layers of acoustic sensor, layers of actuators and layers of encapsulant. The paper addresses the applications of the active acoustic coating with piezoelectric sensors and actuators for the cancellation of underwater sound reflection and transmission in the frequency domain. Computational techniques are reviewed on analyzing multi-layered active coating systems and on calculating the voltages required for the piezoelectric layers to cancel underwater sound reflections and/or transmissions. Non-reflective piezoelectric coatings are discussed for a oblique and/or normal plane sound wave incidence. The formulations such as surface impedance tensor approach and transfer matrix approach are introduced. They account for the complex interaction between the sound waves and the submerged active coating. The design criterion of imbedded sensors in the multi-layered active non-reflective coating is considered.

This paper deals with a newly developed piezoelectric motor that generates precise stepping motion using a piezoelectric torsional actuator and a pair of one-way clutch bearings. The torsional actuator consists of a piezoelectric cylinder that produces rotation motion invoking shear mode of piezoelectric materials and a torsion bar that magnifies the rotation angle produced from the piezoelectric cylinder. Inner one-way clutch bearing is fit on the torsion bar and outer bearing is mounted outside of the inner bearing such that when the torsion bar rotates in one direction, the inner bearing moves together while the outer one slips. When the torsion bar rotates in opposite direction, the inner bearing slips against the torsion bar while the outer bearing locks the inner bearing so as to accumulate the rotation angle. Because the elaborate piezoelectric torsional actuator functions as the driving source at high frequency, a precise step motion with high speed can be produced. The optimum condition for driving the motor is investigated in terms of excitation frequency, electrical impedance and the location of the bearing set. The rotation speed and torque of the motor is investigated, and 350rpm and 0. l9mNm torque are observed in maximum.

The theory of dynamic antiplane piezoelectricity is applied to solve the problem of a circular piezoelectric inclusion embedded in an infinite piezoelectric matrix subjected to horizontally polarized shear waves and a steady-state inplane electrical load. The problem is formulated by means of the wave function expansion method. Numerical values on the dynamic stress and electric field concentrations are obtained, and the results are displayed graphically to exhibit the electroelastic interactions.

It has been shown in our previous work that 28GHz microwave sintering process can improve the performances of piezoelectric actuators. The improved performances include larger output force, higher strength and larger electromechanical coupling factor. The improvement in performances is attributed to the repression of grain growth due to rapid heating and improvement of microstructure because of internal heating. The sintering time was reduced to 1/10 of the time needed for the traditional technology due to the lager power and uniform heating in the microwave sintering process. In this study, the microwave sintering process was combined with hot-press sintering process for further improvement of the performances of PZT actuators and the sintering conditions of the hybrid process were investigated. It has been confirmed that the combination of microwave and hot-press can further improve the performance of sintered PZT actuators by 30%. This process was also successfully used in the sintering of large samples.

Piezoelectric transducer (PZT) patches can be attached to a structure in order to reduce vibration. The PZT patches essentially convert vibrational mechanical energy into electrical energy. The electrical energy can be dissipated via an electrical impedance. Currently, impedance designs require experimental tuning of resistance values by minimizing the H2 norm of the damped system. After the design process, shunt circuits are normally implemented using discrete reasonable performance has been an ongoing and unaddressed problem in shunt damping. A new approach to implementing piezoelectric shunt circuits is presented. A synthetic impedance, consisting of a voltage controlled circuit source and DSP system, is used to synthesize the terminal impedance of a shunt network. A two mode shunt circuit is designed and implemented for an experimental simply supported beam. The second and third structural modes of the beam are reduced in magnitude by 22 and 18 dB.

This paper presents two new designs for a differential-type SMA actuator for a silicon micro gripper. The basic structure of the micro gripper is fabricated by silicon dry etching. The SMA actuators have been realized by machining a NiTi foil with a thickness of 50 ?m. It has been cut by direct laserwriting using a Q-switched Nd:YAG-laser followed by a wet chemical etch step to remove the heat affected zone (HAT). The first design is an advance of a recently presented actuation system with an optimized configuration of the SMA actuator. A critical aspect is the high force necessary to imply the low temperature shape of the inactive actuator which has to be transmitted by the gripper gear. This problem has been overcome by the second design where these high forces are transmitted directly between the active and the inactive actuator of the differential-type actuator. Tests of this new actuator and a new gipper design modified to meet the requirements of the actuator are described.

In this paper, a novel micro assembly method using Shape Memory Alloy (SMA) is investigated. The principle of this method and its advantages are briefly discussed. A finite element package, ANSYS, is used to simulate the whole assembly process. A special material element is used for modeling the behavior of SMA.

Since the phase change in SMA-based devices such as actuators is accompanied by a significant heat exchange with the surroundings, different concepts to heat/cool SMAs have been proposed in the literature. Most of these concepts require the analysis of a multilayered (e.g., "sandwich"-type) structure where the SMA layer is placed between layers with another material. In this paper we propose a mathematical model and an efficient numerical method for this analysis. Although our approach can be applied to a wide range of different designs of multilayered actuators, the basic idea of the model construction is explained in this paper for a specific design based on the introduction of semiconductor "heat pump" modules into the device and the Peltier effect for the heat exchange. The dynamics of thermomechanical fields is studied with a coupled system of PDEs based on conservation laws. The system, supplemented by constitutive relationships in the Falk form, is reduced to a differential-algebraic (DA) model and solved with an effective DA solver developed in our previous works. Numerical results on thermomechanical behaviour of SMA components in multilayered actuators are presented.

This paper describes our investigation of the dynamic, information rich, mOlecular structure of the ultimate smart interface — human skin - by coupling advances in biological, Microsystems, and information technology. The outer layer of human skin, the stratum comeum, is a biologically complex thin film that has unique molecular mechanisms that allow it to function simultaneously as a structural and as a perceptual interface. It is continuously "sampled" by the brain in terms of visual, tactile, and olfactory cues. It interfaces the organism with its environment and has unique micro/nano architecture from an engineering standpoint; e.g., it simultaneously retains and uses water to plasticize the membrane for flexibility. This paper focuses on the development of a sampling interface and MEMS components for a freestanding, multifunctional, multimode, microfluidics-based sensor system for real time physiological monitoring. This research will enable us to gain an insight into the functioning of the human at a fundamental level (from cellular to population) that has not been possible before.

An innovative production technique is described for the low-cost production of arrays of interdigitated electrode (IDE) structures. The resulting polymer chips form the basis of a new type of diagnostic device allowing for the impedimetric detection of either hybridisation or immuno-affinity binding of antibody-antigen combinations. Sensitivity of the IDEs is maximised by focusing the field of sensitivity to the molecules of interest by lowering the electrode dimensions and spacing to the sub-micron region. This has been achieved using a unique combination of state-of-the-art micro-structuring of polymers and the directionality of metal-deposition by evaporation. Subsequently, polymer based arrays of IDEs with micron to sub-micron electrode widths can be realised using a single metallisation step, completely omitting any sophisticated photolithography.

A small Platinum (Pt) electrode (geometric area: ~O.43 mm2) was treated in an electrochemical etching process, to produce a highly porous columnar thin layer (~6OO nm) on the surface of the electrode. The modified Pt electrode (Pt-p) showed similar electrical properties to a platinum-black electrode but with high mechanical integrity. Previous studies of chronic stimulation had also shown good biocompatibility and surface stability over several months implantation. This paper discusses the potential applications of the modified electrode as an implanted bio-sensor: (1) as a recording electrode compared to an untreated Pt electrode. (2) as a probe in detecting electrical characteristics of living biological material adjacent to the electrode in vivo, which may correlate to inflammation or trauma repair. Results of electrochemical impedance spectroscopy (EIS) revealed much lower electrode interface polarisation impedance, reduced overall electrode impedance, and a largely constant impedance above 100 Hz for the Pt-p electrode compared with untreated Pt electrodes. This provides a platform for recording biological events with low noise interference. Results of AC. impedance spectroscopy of the high surface area electrode only reflect changes in the surrounding biological environment in the frequency range (1 kHz to 100 kHz), interference from electrode polarisation impedance can be neglected. The results imply that the surface-modified electrode is a good candidate for application to implantable biosensors for detecting bio-electric events. The modification procedure and its high surface area concept could have application to a smart MEMS device or microelectrode.

Development of a micromachined electrode array for cochlear implant application is presented. The device is constructed from a silicon substrate with sputtered platinum electrodes and connection tracks. Electrochemical impedance spectroscopy (EIS) is used to study the properties of the electrode, and to identify potential problems caused by the micromachining process and materials. A variety of insulators are studied and a two part epoxy is identified as an adequate insulator for operation under harsh electrochemical testing conditions. The semiconducting silicon substrate is found to contribute to the total impedance of the device at high frequencies due to the thin insulating oxide between the substrate and conducting tracks. This is a potential problem for micromachined electrodes operating under high frequencies or using square stimulating pulses. The charge-delivery properties are studied using electrochemical impedance spectroscopy. It is found that platinum sputtered under particular conditions results in excellent surface conditions for optimum charge-delivery.

We report on the use of fiber Bragg grating (FBG) foot sensors to study the reaction of human being subjected to floor vibration. The entire testing system comprises the multiplexed FBG foot sensors, the communication link between the sensors and the vibrating slab, the control and synchronization software, the graphical user interface, and the data acquisition and analysis system. The pressure distributions over different parts of the foot are obtained at different floor vibrating frequencies and with different distances from the vibrating source. These results show great potential in the application of the FBG foot sensors to study the biomechanics of balancing on a vibrating floor. It has also been demonstrated that the system is robust and able to work under harsh conditions. Further development towards practical implementation of the system is proposed.

Magnetic MEMS technology, by exploiting the special properties of magnetic materials, offers many challenging possibilities for useful device development in the future. In this paper we explore some of the magnetic materials used in MEMS devices, and methods of fabricating them. Some of the key design issues are briefly addressed and applications of this technology to electromagnetic devices developed at RMIT and to thermally controlled magnetic devices, which are of increasing interest, are examined.

The main problem with Shape Memory Alloy (SMA) actuators is their slow response speed. Current SMA actuators work in tens of seconds though they can generate large force and displacement outputs. The objective ofthe research in this paper is to improve the response speed of SMA actuators to 1 0 milliseconds or less. SMA actuators are driven by thermal energy and their slow response is attributed to the inefficient heat transfer. To improve the response, direct Ohmic heating was used in the experiments. The SMA actuators used in this study are Ti-Ni-Cu columns of ?5x5O mm with residual strain produced upon unloading after 5.3% axial compression. The transient displacement response of the SMA actuators without axial constraint and the transient force response of the actuators under axial constraint were measured with direct heating. The shortest response time achieved for unconstrained actuators is 4.6 ms and that for constrained actuators is 6.5 ms. The average value of maximum recovery force is 1 O.8kN, which corresponds to 55OMPa of recovery stress. It was also found that constrained actuators need about 50% more energy for heating than unconstrained actuators.

System-on-a-package (SOP) or multi-domain module (MDM), next generation multichip module (MCM) philosophy, offers significant performance promises, and new set of packaging and integration challenges. In packaging and integrating SOP, the drive is not only to increase electrical density, increase operating speed and reduce cost per part but also the major advantage is to make system SMART by increasing functional density per unit area and/or per unit volume. Functional spectrum not only includes electrical domain with elements such as control, processing, memory, etc. but also, various other domains or signals such as mechanical, optical, chemical, magnetic, biological for sensing and/or for actuation. MEMS and related microsystems are used for various mechanical, optical, chemical and biological sensing and actuation, and are the important elements of SOPs. This paper discusses packaging and integration advantages and challenges of MEMS and related microsystems for SOP. Philosophical difference in packaging IC versus MEMS is that IC really never wants to "touch" media where MEMS and related systems are designed to integrate with media for sensing jnd actuation. Various MEMS and micro-systems packaging related issues are dicing, handling, wafer-level packaging, media compatibility, outgassing and vacuum packaging, interconnection, etc. This paper will discuss SOP related MEMS and microsystem packaging and integration issues.

In This report, Silicon wafer based print circuit board is presented as an example of application of this technique, where the metal was filled into ICP fabricated through holes to make electrical feed through. The target application of this work is Silicon based print circuit board. The electrical feed through was fabricated by casting the Ag (80 wt %) + Cu (20 wt %) mixed with binder into the small diameter through holes in oxidized silicon wafer. A multi-component binder system comprising of EVA (Ethylene Vinyl Acetate 35 wt %) + PW (Paraffin Wax 65 wt %) was used. Super critical debinding method is applied prior to final sintering process. The ratio of metal powder and binder was 9:1. SEM observation shows that the through holes are filled with metal powders. Conventional debinding process resulted in scattering the metal powder onto the Si wafer during debinding process and final sintering process. Very slow temperature elevation heating and super critical debinding process resulted in good formation of electrical feed through. The feed through formed with small bumps because of expansion of the metal powder area. The electrical conductivity test was sufficient between top and bottom. Several Feed through formation methods have been proposed. The electroplating and vacuum casting method are well known processes. Compared with these methods, this is rather rapid and economical, and provides desired shape of bumps and no need of eliminating the unnecessary part.

The development of an on line computer based classification system for the real time classification of different composites is addressed in this study. Different parameters were collected simultaneously when embeded sensors (dielectric, optical fiber, and piezoelectric sensors) were used within two different composite matrices during the curing process. The measurements were used by an algorithm software as a logged data file, resulting in to inducing a decision tree. Later, a systematic software is designed based on the rules derived from this decision tree, to recognise the type of composites used in the experiment together with recognition of their physical and mechanical characteristics. This is a new approach to data acquisition in intelligent materials produced by smart manufacturing system.

The reflection of ultrasonic Lamb waves produced by a periodic array of thin conducting or mass loading strips is investigated both theoretically as well as experimentally. A repetitively mismatched transmission line model is used to analyze the performance of the reflector. It is found that Lamb waves propagating in thin elastic plates can be reflected much more efficiently than surface acoustic waves (SAWs). Efficient reflectors can therefore be realized with relatively few strips in the array. The characteristics of a number of reflectors fabricated on thin plates of lithium niobate have been evaluated and found to be in good agreement with theory. The reflectors have been used to realize various useful devices such as unidirectional transducers, low loss, wide bandwidth delay lines, and Lamb wave resonators.

Smart structures incorporate sensors, actuators and control electronics that permit the structures to tailor their response to changes in the environment in an optimal fashion. The sensors and actuators are constructed from functional materials such as piezoelectric, electrostrictive, shape memory alloys and magnetostrictive materials and more recently using MEMS (Micro Electro Mechanical Systems) devices. All functional materials and devices therefrom involve coupled fields involving elastodynamic, viscoelastic, electric, magnetic and thermal fields. The materials are anisotropic and often nonlinear. Finite element modeling has been successfully used to model these complex structures. More recently, closed ioop numerical simulation of the tailored response of a smart structure has become possible by combining the finite element equations of the sensor response to applied dynamical and/or thermal loads to the input voltage or current to the actuators via a control algorithm. This hybrid approach permits us to simulate the response of the structure with feedback control. Simple feedback controllers have now been replaced by robust controllers that provide stability under a range of uncertainties and do not require a very accurate system model. The talk will present an overview of the approaches of various researchers and consider numerical applications and comparison with experiments for active vibration damping, noise control and shape modification.

Limiting structural response by increasing damping with passive devices it is attractive because these elements, even if they fail to work properly, will never introduce mechanical energy into the structure. Thus although active control results more efficient, nevertheless possible malfunction of the control system or the changed properties of mechanical components, during lifetime, may cause the control system itself to trouble the structure dynamics. That is especially true in space, where external operations are difficult or even impossible and the system must work for lifetimes of years in the space environment (radiations, space debris, etc.). In this paper piezoceramic materials, suitably loaded with either resistors or resistors and inductors, are considered. The similarity of the piezo device complex stiffness with the ones used for viscoelastic material models allows one to simulate, with relative ease, the behaviour of a structure equipped with passive piezo devices by the use of general purpose finite element codes. Finite element models of a beam and one model of a plate are considered as test cases. Estimations of the damping coefficients, introduced by the passive devices, are in excellent agreement in the different models of the beam considered and are consistent in the case of the plate.

This paper presents a new method to identify the vibration model for large smart structures. A large structure typically has low frequency vibrations, unique distributed dynamic characteristics, and no simple control model. Study of composite aircraft fuselage vibration suppression required the identification of a distributed parameter control method. Artificial neural networks were used to identify structural vibration characteristics in distinct neighborhoods. Neural networks were trained and compared using a plate model.

Elastic instability is often the limiting factor in the design of thin-walled structural components, accentuated by the imperfections typical of real structures. Smart structures have the potential to use piezoelectric or shape memory materials to actively generate stabilizing internal forces. These smart materials can be made into in-plane actuator layers and added to both surfaces of the structure to generate bending couples. In spite of the interest in smart structures, the potential of active tailoring and control of buckling has received scant attention. This paper examines the capacity of such actuator layer pairs to change the compression buckling loads of thin structures by interfering with the development of incipient buckling mode shapes. Amo del is formulated that idealizes the actuator layers as nonlinear springs that impede or promote out-of-plane bending until a saturation bending moment is reached. Acommercial finite element software package is used to solve the resulting non-linear equilibrium equations for a selection of materials, geometries, and structure sizes, to investigate the sensitivities of the buckling suppression effect. Overall the results show that smart laminates can actively interact with their instabilities and minimize the effect of imperfections. Although substantial gains in buckling load can be achieved in some cases, the relative effectiveness of active stabilization control is strongly dependent on the characteristics of structure, sensors and actuators.

Two kinds ofsmart force sensors for the force distribution measurements are presented in this paper. The force distribution testing technique is widely used in intelligent control of robot and biomechanics. Usually a sensor matrix that includes hundreds to thousands micro sensor elements is adopted and that will provides the precise force distribution information for the different requirements. Two kinds of sensor material the piezoelectric ceramic, PVDF and piezo-resistance sensor conducting rubber are introduced in this paper. The requirements ofthe smart structure and the signal processing technique are discussed. Three smart force sensor systems are developed for the robot and biomechanics applications. Some image processing techniques are developed for the signal analysis and data processing.

Measurement of temperature using optical methods has been successfully employed in industrial environments where conventional techniques become unreliable. The sensor shows sufficient sensitivity to thermal variations whilst being substantially insensitive to strain. The most promising rare-earth elements for further development have been identified.

It is known that certain design consideration must be given to the concrete structures to cater for possible ambient temperature variations. The thermal stress that results from these changes can cause damage in concrete structures ifthey are restrained or ignored in the design stage. The thermal effects in concrete structures are mainly due to the surrounding environmental conditions and some other special effects, such as the heat of hydration during construction and casting of the bitumen. In this paper, we present our preliminary results on monitoring the non-linear temperature profiles of simulated bridge decks due to various environmental contributing factors using fiber Bragg grating (FBG) sensors and thermocouples. We will also present the data on the variations of the temperature profiles in the concrete due to different thickness of the bitumen topping.

Metallophthalocyanines synthesized for different metals such as Ni, Cr, Ag, Mg, Cu, Cd, Al, etc by chemical methods were characterized with FTIR, TGA etc. Sensing of humidity and different gases such as NOx, H2, O2, CO2. N2, ammonia, alcohol vapours etc were checked with 2-probe technique with monitoring change in resistance change. These samples have excellent stability against heat, light, air, and hence it has considerable attention for environmentally stable gas sensor. The electrical property of these samples were investigated at room teniperature and at normal atmospheric pressure from low to 98% relative Humidity. It was observed that these samples shows good response and recovery for humidity sensing.

Polyaniline(PANI) was doped with different dopants like camphosulphonic acid (CSA), diphenyl phosphate(DPPH), suiphonic acid(S), and Maleic acid (MAC) by chemical method. The samples were prepared in the form of pellets as well as films. Polyaniline doped with Maleic acid was found to be mechanically and chemically stable as compared to other dopants and therefore the effect of humidity on conductivity was further investigated. Films prepared out of styrene butyl acrylate copolymer with different concentrations of PANT Maleic acid were used for sensing humidity ranging between 20% to 90% relative humidity. A maximum change in the conductivity of three to four orders of magnitude was obtained for the Maleic acid doped polyaniline pellet while two order of magnitude change was obtained for the film samples over the range of humidity measured.

Electrostrictive actuators are a relatively new development in the field of smart material actuators. However, a major deficiency of electrostrictive actuators is their limitation of motion accuracy due to inherent non-linearity and hysteresis. This paper presents a new iterative learning control approach to improve the positioning/tracking accuracy of electrostrictive actuators. In this scheme, the iterative gain is not fixed but variable according to previous trial result and the nominal input/output relationship of the electrostrictive actuator. The convergence to the desired position/trajectory is theoretically proved. The effectiveness ofthis control scheme is experimentally demonstrated through actual positioning and tracking control ofa stacked electrostrictive actuator. The results show that using this variable gain iterative learning control scheme, not only can the stability of precision positioning be obviously improved, but also precise and non-delay tracking can be achieved.

There is considerable interest in the use of piezoelectric ceramic actuators for vibration suppression of thin lightly damped structures. One technique receiving much attention is to 'actively' drive the piezoelectric ceramic to control the out-of-plane vibration of the structure, this technique requires an external power source. Another technique involves using an R-L resonant shunt, with the piezoelectric element, to achieve single-mode passive vibration control of the structure - analogous to a mechanically tuned mass damper. The R-L resonant shunt scheme requires large inductors making this technique difficult to implement unless an active inductance, requiring an external power supply, is used. This paper looks at the concept of a self -powered discrete time piezoelectric damper that uses piezoelectric elements as the power source, sensor and actuator. The device uses a small portion of the electrical energy produced by the piezoelectric elements to power the electronic circuitry, thus eliminating the requirement for an external power source. The circuit controls the transfer of electrical energy between a storage device (capacitor) and the piezoelectric elements, which also operate as an actuator to suppress vibration. This approach does not need large value inductors such as required for passive tuned R-L resonant shunt damper and does not require tuning to the structural resonant frequency. The design concepts of a self-powered discrete time piezoelectric vibration damper are discussed in this paper. This device is referred to as a STrain Amplitude Minimisation Patch (STAMP) damper. Initial experimental results have shown that a concept demonstrator of the non-optimised STAMP damper system had better damping than the simple resistor shunt damper but not as good as the tuned R-L resonant shunt damper. This paper outlines, in more detail, the theoretical analysis of the STAMP damper system thus illustrating the fundamental differences between more conventional passive techniques such as resistor and R-L resonant shunts with piezoceramic elements. The aim of the paper is to theoretically show the benefits of the STAMP damper compared to other piezoceramic-based vibration damping concepts. A case study of the operation of the three systems, resistor, R-L resonant shunt and STAMP system, on a cantilevered beam system is undertaken. The case study quantifies the vibration reduction mechanisms of each system studied. It is shown that, as expected, the resistor shunt system dissipates energy in the resistor element to achieve vibration suppression. However, both the tuned R-L resonant shunt and the STAMP systems achieve their significant vibration reduction by producing a voltage component across the piezoceramic elements which is in-phase with the system velocity, rather than by power dissipated in the purely resistive components. The "STAMP" circuit has no intentional dissipation element, instead using the "harvested" power to drive the piezoelectric ceramic element, thus it generated the largest in-phase piezoelectric voltage component and thus, potentially, the largest effect on damping (of the methodologies analysed). The tuning requirements were also examined, illustrating the relatively narrow range of effective operating frequencies for the R-L damper scheme compared with the pure resistor or STAMP techniques.

Due to economic pressures both commercial and military aircraft fleets are operating a greater number of ageing aircraft. It can therefore be expected that the occurrence of structurally significant defects will significantly increase in the future. In the Australian context, a significant portion of the Royal Australian Air Force fleet are being operated well past the designed life. For example the F-111C fleet will be in service till the year 2015 which is about 20 years more than the original design life of the aircraft. As fleets get older a greater share of the operator's resources need to be used on through-life-support of the airframe. One way of reducing costs and increasing aircraft availability is through the use of smart materials technology. Smart materials are materials with the ability to respond to changes in the operating environment or to other stimuli in an intelligent way. This ability may be achieved from sensors and actuators embedded in or attached to the structure or, more simply, from an inherent response mechanism in the material. In the context of ageing airframes, smart materials/structures technology has excellent potential to provide improvements in through-life support, including health and usage monitoring (HUMS), with the eventual aim of allowing condition based maintenance procedures to be adopted rather then relying on current expensive time-based maintenance procedures. This paper discusses the development and evaluation in DSTO of smart structure technologies to be applied to structural health monitoring of aircraft structures. Systems are being developed by DSTO with the specific aim of retro-fitting to existing airframe structures (e.g. smart repairs and reinforcements with the ability to self-monitor patch system integrity), where the systems need to be autonomous, distributed, robust and reliable. The paper expands on the health monitoring techniques being developed and evaluated, including the use of electrical-resistance foil strain gauges, piezoelectric elements and optical fibre sensors. Since the emphasis here is on retrofitting systems to existing structures the paper also touches on ftilly-autonomous systems which incorporate self-powering and wireless access techniques.

Large vibrations in structures are normally unwanted due to corresponding large displacements and accelerations. Other deleterious effects may be caused by the large stresses which are coexistent with these large vibrations; resulting in ultimate failure or at the very least a dramatic reduction in the fatigue life of the structure. A possible solution to this problem is to adopt a "smart structures" approach by using piezoceramic actuators in a feedback control loop to reduce these unwanted vibrations. Two distinct problems will be considered here (although distinct they are of equal importance to the whole control system ).The first problem is the optimal placement of piezoceramics for a given amount of material so as to obtain "maximum modal controllability". A cantilevered plate is examined as an example. The second problem considered is the design of robust optimal controllers which maximize the damping of the lightest damped mode in the closed ioop system. Restricting the position of the poles of the controller to lie within a certain domain effectively limits the bandwidth of the controller and ensures robustness. The non-linear problem of maximizing the minimum damping using only a certain amount of control energy whilst the controller is restricted in the aforementioned way is solved. In the case of expensive control energy which motivates our study it is seen that the results agree with our intuition via some simple examples.

Piezo-electric (PVDF) sensors were applied to a specifically prepared two-sided composite specimen. The specimen was fatigued with a 3Hz cyclic load until the adhesive bond between composite patch and aluminium failed. During the cyclic loading period the output from the PVDF sensors were monitored by a prototype "Smart Patch Device". The Smart Patch Device measured outputs from two PVDF sensors, one on the "patch" and one in the "far-field" from which was calculated a "Patch state of health". The Smart Patch Device successfully detected the composite patch disbonding from the aluminium. The effect of the adhesive spew fillet, which can produce significant strains in disbonded sections of patch, is considered. Finally a number of points in relation to the use of the strain ratio technique for patch state of health monitoring are elucidated..

LQR vibration control of piezoelectric composite plates is investigated via the finite element method. Laminated composite plates with bounded or embedded piezoelectric sensors (PVDFs) and actuators (PZTs) are discretized by an isoparametric element and the governing equations of motion are derived by using the Hamilton's principle. The optimal LQR method is used to couple the discrete distributed actuation and sensing. The Algebraic Riccati Equation (ARE) is solved by MATLAB. To avoid possible numerical difficulty, in the present study only Potter's method rather than MATLAB 's control toolbox functions is used. More emphasis is put on appropriate selection of the weighting matrices of the optimal quadratic objective functions. The present study tried to relate the quadratic functions with some physical meanings to avoid the usual trial and error procedure. The quadratic functions are assumed to consist of independent strain energy, kinetic energy and actuators' input energy. The frequency matrix and the identity matrix are used as the relative weight of the strain energy and the kinetic energy and the actuators' input energy with an adjustable coefficient for each actuator is used as the relative weight of the actuators' input energy. Numerical results show that this method works fairly well for either the output constraint control (0CC) or input constraint control (ICC) and the active damping effect is more sensitive when approaching the breakdown voltages of the actuators.

In this paper, the snap-down phenomenon in an electrostatically-actuated torsional micromirror is investigated. Based on the static actuation relation of torsional micromirrors, the relationship between snap-down angle and the structural parameters of the torsional micromirror is derived. It is shown that the snap-down angle is mainly determined by the size and position of the electrodes. Most importantly, it is found that the product of the normalized snap-down angle and the normalized size of the electrode is equal to a constant of 0.4404, which is universal for all torsional micromirrors of this kind of configuration, and is very useful for micromirror design. The relationship between the maximum driving voltage and the snap-down angle is also studied. Finally, a group of torsional micromirrors has been fabricated using multi-layer polysilicon processes, and then been tested to verify the analysis.

The use of Bragg grating optical fibre sensors for damage detection and health monitoring of highly loaded structural features in diverse stress fields is evaluated numerically. A composite patch bonded to a metallic 'crotch' specimen is considered. The specimen is representative of both high and low load transfer regions, with areas of high peel and shear. Sensors distributed along two optical fibres embedded in the composite patch, one near the surface and the other near the bond-line, are capable of detecting disbond damage between the substrate plate and the patch under tensile and residual (thermal) loading. Damage detection sensitivity is investigated in various regions along the bond-line. The axial strains in the optical fibre are used as the primary indicator of damage but shear strains can be equally effective, given the availability of suitable sensor technology. The presence of damage is indicated by discrepancies between the strain readings across the thickness of the patch (jatch bending) or by discontinuities in strain distribution along the fibre. Also the response of the Bragg grating to the various strain gradients is also numerically modelled in order to understand the effects of the severe strain gradients on the reflected Bragg grating optical spectrum.

In this paper we critique the first order quantum efficiency and modulation transfer function (MTF) analysis for photocollection in both a finite and semi-infinite slab of semiconducting material. We derive the correct equations from first principles and perform a case study comparing photodetection in silicon and GaAs. This is of interest in the first order design of GaAs and silicon optical smart sensors and solid-state imagers.

T-ray systems o er an exciting range of capabilities for chemical and biological diagnostics using the emerging technology of terahertz pulse imaging.1,2 We report results from the rst Australian T-ray program and discuss how MOEMS techniques can be applied to decrease the system size.3 A small portable T-Ray system will cost less and is needed, for example, in endoscopic applications.4

This paper is concerned with the development of an active palpation sensor for detecting the prostatic cancer and hypertrophy. The receptor of the sensor is a polyvinylidene fluoride (PVDF) film placed on the surface of a sponge rubber layer. It is mounted on a linear z-translation bar and inserted into the examinee's rectum being protected by a medical rubber glove. After positioned faced to the prostate gland, the sensor probe is driven sinusoidally at about 50Hz with peak-to-peak amplitude 2mm. The voltage signal from the PVDF film is integrated over the sampling period and used as the output of sensor for extracting the features of the collected data. The evaluation of stiffness by the sensor on 27 normal and unhealthy prostate glands are compared with the results of diagnosis by the doctor's palpation. It is shown that the output of sensor becomes greater with an increase of the stiffness of the prostate gland, which has good correlation with the doctor's evaluation on the stiffness. Further results on the laboratory test reconfirm that the present sensor well discriminates the stiffness of the prostate glands in vivo and non-invasively.

The plasma membrane, that exists as part of many animal and plant cells, is a regulator for the transport of ions and small molecules across cell boundaries. Two main components involved are the phospholipid bilayer and the transport proteins. This paper details the construction of a micromachined support for bilayers (MSB) as a first step towards the development of highly selective and highly sensitive ion-channel based biosensors. The device consists of a ~100 ?m hole in a polymeric support above a cavity that can hold ~25 nL of electrolyte. Electrodes attached to the structure allow the resistance of the membranes to be measured using d.c. conductivity. The MSB is made in two halves, using SU8 ultra-thick resist, which are subsequently bonded together to make the final structure. A layer of gold, surrounding the aperture, enables self-assembled monolayers of alkanethiols to be used to make the polymeric structure biocompatible. Lipid membranes have been formed over these holes with resistances comparable with those of natural membranes >107 ?cm2. The ion-channel gramicidin has successfully been incorporated into the bilayer and its activity monitored. It is proposed that this type of device could be used not only for studying membrane transport phenomena but also as part of an ion-channel based biosensor.

This paper reports on an experimental program aimed at assessing the feasibility of monitoring crack growth by means of a surface-mounted piezotransducer array. The host structure is interrogated using lamb-waves generated and sensed by elements in the array. An example is described involving a uniaxial edge-notched specimen subject to cyclic loading where the array is shown to be capable of detecting on a sustained basis crack growth increments of less than 0.1 mm. Although the piezoceramic elements were exposed to cyclic stress there was no measurable indication of element degradation,indica ting good fatigue durability properties under the loading regime considered. Experimental results are also shown that demonstrate a strong crack-state dependence,hig hlighting the need for care when interpreting signals from the piezotransducers.

This work investigates a radical new approach for plasma display production that is potentially easier to produce and results in plasma displays that are of significantly higher resolution. Most of the current modern plasma displays operate on essentially the same principle as a cathode ray tube. Using this technique, plasma displays are capable of resolutions of 1024 by 1024 pixels on a 42-inch display [1]. This is equivalent to 215 pixels per square cm. In this paper we propose a new application of the Coherent Porous Silicon enabled fabrication technique that can be used to develop a display that contains 250,000 discharge lamps per square centimeter. This is over three orders of magnitude better density than the current displays. The core CPS technology at the heart of this application can be used to produce substrates with over 1,000,000 pores per square centimeter, allowing development of even higher density displays. The paper discusses the fabrication technology and underlying experiments that have been successfully conducted to validate the concept and reports on the feasibility studies that have been carried out.

Thick-insulating-ceramic-type thin-film electroluminescent (TFEL) devices with an oxide phosphor thin-film emitting layer have been fabricated by a sol-gel process that uses various source materials and eliminates the need for vacuum processes. The oxide phosphor thin-film emitting layer consisted of host materials such as Ga2O3, SnO2, ZnGa2O4 and (Ga2O3-Al2O3) multicomponent oxides activated with a transition metal element such as Mn and Cr or a rare earth element such as Eu. High luminances were obtained in TFEL devices with a Ga2O3:Mn, Ga2O3:Cr, SnO2:Eu, ZnGa2O4:Mn or (Ga2O3-Al2O3):Mn phosphor thin-film emitting layer. Luminances above 400 cd/m2 were obtained in green-emitting TFEL devices using Ga2O3:Mn thin films prepared by the sol-gel process, irrespective of source materials, when driven at 60 Hz. It was found that the EL characteristics of oxide phosphor TFEL devices improved as the driving frequency was increased from 60 Hz to 1 kHz. In a Mn- and Cr-co-doped Ga2O3 phosphor TFEL device, an emission color change from green to red as well as high luminances above 100 cd/m2 were obtained when driven at 10 kHz.

Vehicle suspension is normally used to attenuate unwanted vibration from various road conditions. The successful suppression of the vibration leads to the improvement of ride comfort as well as steering stability. One of attractive candidates to formulate successful vehicle suspension is to use ER(electrorheological) fluid damper. This paper presents robust control performances of ER suspension system subjected to mass and time constant uncertainties. After identifying dynamic bandwidth of a cylindrical ER damper associated with two different ER fluids(one has fast response characteristic, while the other has slow response characteristic), a quarter car model is established by incorporating with time constant of the damping force. A robust H? controller, which compensates mass and time constant uncertainties, is designed in order to suppress unwanted vibration of the vehicle suspension. Control responses such as vertical acceleration are presented in time domain. In addition, the effect of time constant of the damping force on the vibration control performance is investigated via comparative work between fast and slow dynamic characteristics of the ER damper. The control responses presented in this work will provide very useful guidelines in adopting proper ER fluids for right application devices.

Impedance-frequency characteristics of several types of bio-electrodes, platinum (Pt), modified Pt, iridium (Ir), and iridium oxides, are presented in this paper. The study aimed at investigating the effects of bio-electrode array design and biological environments on the impedance behavior. Electrochemical impedance spectra were measured in physiological saline, and additional data were obtained from in vivo animal studies using implanted electrodes. The frequency spectrum can be approximately divided into three regions, in which different factors are dominant. At 1 kHz to 100 kHz or higher, impedance is mainly determined by the electrode geometric area and biological materials adjacent to the electrode. The impedance of a micromachined thin film connector track could contribute in this region. At the low frequency region of 1 Hz (or lower) to 100 Hz, electrode material, the electrode real surface area and electrode potential play a dominant role in the impedance. There is a mix of these factors in the middle frequency region, 100 Hz to 1 kHz. However, the boundaries of the three regions are not fixed, but rather shift depending on the individual electrode. In the case of microelectrodes, the boundaries move towards high frequencies. Results showed that the effect of material selection and surface modification on impedance was more pronounced in the case of smaller electrodes, or when relatively low frequencies were used. The responses of living tissue to implants resulted in changes in the biological environment near the implanted electrodes and this led to a large increase in impedance at high frequencies. The impedance-frequency characteristic provides a guideline for a bio-electrode array design to meet a particular bio-medical application, and also an evaluation method for bio-electrode arrays.

The electric fracture behaviour of a piezoelectric ceramic under applied electric fields has been discussed through experimental and theoretical characterizations. The single –edge precracked beam tests were performed on a commercial lead zirconate titanate ceramic. Mechanical loading was applied by the crosshead displacement control of the screw-driven electromechanical test machine. The fracture initiation loads under different electric fields are obtained from the experiment. It is shown that the crack opens less under a positive electric field (electric field in poling direction) than under a negative electric field. A finite element analysis was also employed to calculate the energy release rate and stress intensity factor, and to study the validity of the electrical boundary conditions at the crack surfaces to the permeable in piezoelectric material. An expression is presented for determining the fracture properties due to electrical effects by experimental and theoretical means. For a given displacement, the energy release rate is lower for positive electric fields and higher for negative electric fields. This is in agreement with the experimental findings. The numerical results under an applied force are in contrast to those under a constant displacement, and consistent with the relevant experimental results.

Recently, there have been extensive investigations on the shape control of beams using piezoelectric actuators. Most studies, however, assumed linear piezoelectric constitutive equations, which are not valid for actuations involving high electric fields. This paper examines the effect of nonlinear behavior of the piezoelectric materials in the shape control of piezoelectric beams. The governing coupled electromechanical equations for nonlinear material behavior is developed for a general three-dimensional structural element using the Gibbs free energy formulation. Nonlinearity is accounted in the analysis by incorporating an adequate number of nonlinear terms in the Gibbs free energy expression. Since many of the higher order material properties are not available for most of the piezoelectric materials, experimental data that are available for the nonlinear relationship between the electric field and the electric displacement are used. A finite element model is developed for the beam with piezoelectric actuators using a modified bilinear four-node quadratic element. The expression for the actuation voltages required for shape control is then obtained by minimizing an error function, defined as the area between the achieved and desired shape. The final system of coupled equations is solved by an iterative finite element procedure. Comparison of numerical results obtained for both linear and nonlinear piezoelectric behaviors showed the importance of incorporating nonlinear effects in the shape control of piezoelectric beams.

Presently the world has entered the era of Smart Structures. India with its recent strides and emphasis on science and technology is looking forward to making in roads into this emerging multidisciplinary technology area. As a major step forward, a national programme is initiated in India to develop this technology and demonstrate systems for various applications. The paper presents some ofthe initiatives taken in India to develop materials and technologies for MEMS.

MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties, and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors. However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophyllic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments. Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS-MMAs) is 10,000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS-MMA applications. A thin film deposition process has been developed that produces phase-pure ultrananocrystalline diamond (UNCD) with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. We have developed lithographic techniques for the fabrication of diamond microstructures including cantilevers and multi-level devices, acting as precursors to micro-bearings and gears, making UNCD a promising material for the development of high performance MEMS devices.

For those working in the MEMS field, creating microscale motion with improved functionality and efficacy is the challenge ahead. This challenge can be met through biomimetics—imitating nature. Nature, after all, has had almost four billion years to perfect its mastery, whereas MEMS engineers and chemists have been at it for no more than a few decades. Nature's solution to the challenge of microscale movement appears to be the polymer-gel phase-transition. The cytoplasm is a gel—it exhibits all ofthe gels' signature characteristics. By undergoing phase-transition, gels generate both solvent and solute movement. It is argued that cells do the same. Two examples are given: the secretory system and the muscle-contraction system. In each case it is shown that the characteristic motions are created as proteins and water undergo transition from an expanded, hydrated state to a contracted, dehydrated state. This transition displaces solutes and solvent. By exploiting these natural principles, MEMS may have the capacity to generate microscale motions of unprecedented efficacy and simplicity.