In this thesis, the author proposes and presents a novel simulation technique for the analysis of multilayered Flexural Plate Wave (FPW) devices based on the convergence of the Finite Element method (FEM) with classical Surface Acoustic Wave (SAW) analysis techniques and related procedures. Excellent agreement has been obtained between the author's approach and other more conventional modelling techniques. Utilisation of the FEM allows the performance characteristics of a FPW structure to be critically investigated and refined before undertaking the costly task of fabrication. Based on a series of guidelines developed by the author, it is believed the proposed technique can also be applied to other acoustic wave devices. The modelling process developed is quite unique as it is independent of the problem geometry as verified by both two and three dimensional simulations. A critical review of FEM simulation parameters is presented and their effect on the frequency domain response of a FPW transducer given. The technique is also capable of simultaneously modelling various second-order effects, such as triple transit, diffraction and electromagnetic feedthrough, which often requires the application of several different analysis methodologies. To verify the results obtained by the author's novel approach, several commonly used numerical techniques are discussed and their limitations investigated. The author initially considers the Transmission Matrix method, where it is shown that an inherent numerical instability prevents solution convergence when applied to large frequency-thickness products and complex material properties which are characteristic of liquids. In addition the Stiffness Matrix method is investigated, which is shown to be unconditionally stable. Based on this technique, particle displacement profiles and mass sensitivity are presented for multilayered FPW structures and compared against simpler single layer devices commonly quoted in literature. Significant differences are found in mass sensitivity between single layer and multilayered structures. Frequency response characteristics of a FPW device are then explored via a spectral domain Green's function, which serves as a further verification technique of the author's novel analysi s procedure. Modifications to the spectral domain Green's function are discussed and implemented due to the change in solution geometry from SAW to FPW structures. Using the developed techniques, an analysis is undertaken on the applicability of FPW devices for sensing applications in liquid media. Additions are made to both the Stiffness Matrix method and FEM to allow these techniques to accurately incorporate the influence of a liquid layer. The FEM based approach is then applied to obtain the frequency domain characteristics of a liquid loaded FPW structure, where promising results have been obtained. Displacement profiles are considered in liquid media, where it is shown that a tightly coupled Scholte wave exists that is deemed responsible for most reported liquid sensing results. The author concludes the theoretical analysis with an in-depth analysis of a FPW device when applied to density, viscosity and mass sensing applications in liquid media. It is shown that a single FPW device is potentially capable of discriminating between density and viscosity effects, which is typically a task that requires a complex and costly sensor array.

This thesis consists of two topics. A frequency-shift readout circuit is integrated for the rapid IgE measurement biomedical system in the first half. Secondly, we present a ROM-less DDFS (direct digital frequency synthesis) using a non-equal division parabolic polynomial interpolation method, which is used as the frequency generator in the measurement system. The first topic investigates the IgE concentration measurement system and realizes the readout circuit using TSMC 1P6M 0.18 £gm CMOS technology. We integrate the flexural plate wave (FPW) sensor chips and an ASIC comprising control block, digital to analog convertor (DAC), OTA-C oscillators, amplifiers, peak detectors, registers, and a subtractor. By taking advantages of the characteristics that the central frequencies of the loaded FPW sensors will be shifted, sine waves with various frequencies are generated and swept through one pair of FPW sensors. The frequency difference of these sensors is then readout to get concentration by look-up table. The second topic investigates the division method of a quarter sine wave to improve the spurious free dynamic range (SFDR) and realizes a ROM-less DDFS which is used as the frequency generator in the mentioned IgE measurement system. The proposed non-equal division parabolic polynomial interpolation method will generate a complete sine wave by a quarter of a sine digital signal owing to the symmetry. We combine the quasi-linear interpolation and an offset adjustment to derive the quarter sine wave digital signals. The proposed method not only reduces the absolute error between ideal sine wave and generated sine wave, it also improves SFDR.

By integrating Nanotechnology and MEMS technology, this thesis aims to research a flexural-plate wave (FPW) sensor for testing Immunoglobulin E (IgE) concentration in blood serum, a significant index for the diagnosis of allergies. The traditional methods of blood assay are time-consuming and costly, and its average accuracy of only 60-70 percent. After compare the major four kinds of acoustic sensor, the FPW sensor demonstrates a high accuracy, high sensitivity, low operation frequency, low diagnosis time and low cost. This thesis utilizes a reactive RF sputter system to deposite the piezoelectric ZnO thin film. To obtain the high C-axis orientation (002) characteristic of ZnO membrane, many parameters such as substrate temperature, Ar/O2 ratio and RF power have been adjusted and optimized during the sputtering process. The effects of varied parameters will be investigated and analysis by using SEM or XRD facilities. In this study, we combined the high figure-of-merits ZnO deposition techniques and single-side anisotropic silicon etch process to implement the process integration of FPW device. Finally, this research has demonstrated a 50-60MHz center frequency can be extracted from such silicon-based FPW microsensor.

This thesis proposes a dB-linear programmable variable gain amplifier (VGA) and a voltage peak detector with digital calibration for FPW-based antibody sensing system. In the first topic, a dB-linear programmable variable gain amplifier is proposed. By using two source followers as the input terminals, input signals with very low DC offset could be received. The linear local-feedback transconductors are employed to be trans-condurctor-stage and load-stage. Besides, a reconfiguration method is used to reduce the layout area and improve the linearity of the gain to attain gain error less than 0.86 dB measured on silicon. In the second topic, a voltage peak detector with digital calibration is proposed. The voltage peak of the input sine-wave signal is sampled and held by using an integra-tor, a digital-to-analog converter, and a voltage comparator to generate a square-wave signal. Besides, the voltage error caused by the propagation delay could be calibrated by the proposed digital calibration method. The frequency of input signal is up to 20 MHz and the voltage error is justified to be less than 0.81 % by simulations.

The main subject of this thesis is to design a voltage peak detector for FPW-based IgE measurement systems. Therefore, two different peak detectors are proposed. The first voltage peak detector basically samples the input signal twice (double sampling) to reduce the ripples appearing during the sample and hold modes. This voltage peak detector also resolves the detection error of conventional voltage peak detectors when they are used to detect the output signal of FPW-based biosensors.The fastest signal which this voltage peak detector can detect is 10 MHz. The second voltage peak detector is composed of a coupling capacitor, an unity gain buffer, an 8th order voltage control voltage source(VCVS) low pass filter, and a non-inverting amplifier. The major difference of this design from the previous one is to filter and amplify the input signal. The specification requirements of the operational transconductance amplifier in this voltage peak detector can be relaxed thereafter. The resolution and performance of the sensing system are also improved. By replacing the conventional power MOS by a non-inverting amplifier, the charging time is reduced and over charge hazard is avoided. Besides, the speed of the entire system is enhanced. The fastest signal which this voltage peak detector can detect is 50 MHz and the precision is 0.357 %.

Current MEMS development is driven by the need to develop various 'Miniaturized Total Chemical Analysis Systems ([mu]TAS), biological and chemical sensing, drug delivery, molecular separation, microfiltration, amplification, and sequencing systems. In this work, the use of flexural plate wave devices as an actuator has been investigated.This research was done with the aim of developing a platform to build FPW devices for use in System-On-Chip applications. It is well known that acoustic forces generated by a flexural plate wave (FPW) device can cause fluid motion, by the principle of acoustic streaming. Also the proven ability of FPW devices to cause mixing, filtration and to work as a chemical-biological sensor can be used towards building a micromachined [mu]TAS. The effects of the IDT finger width, spacing, aperture, membrane thickness, and driving conditions on the device performance was studied to understand the impact of IDT design on device performance.