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The development of a shear horizontal surface acoustic wave (SH-SAW) liquid sensor with identification (ID) for wireless applications is described. Moreover, a novel feature of "write capability" for this sensor is proposed. The SH-SAW passive sensor has a delay line configuration with a sensing area. The sensor is fabricated on a lithium tantalate (LiTa03) substrate, which is Y-cut with rotations specified between about 36° around the X-axis. The principle of detection is based on the attenuation and time delay between the signals. The sensor is encoded according to partial reflections of an interrogation signal by metal reflectors placed on both side of the interdigital transducers (IDT). The structure of the sensor, the principle of the wireless communication, the detection process and testing results are presented.

MEMS accelerometers are extensively employed in various consumer applications due to their rapidly decreasing costs. In order to meet the low-cost requirements, manufacturers are forced to sacrifice some design parameters that may degrade their accelerometers' reliabilities. Interestingly, there is not much published works on the reliability aspects of MEMS accelerometers. Two reports detailed the reliability qualitative assessment on commercial devices [1–2]. Both works concluded that MEMS accelerometers are high reliable devices with low failure rates. In a recent study [3], a procedure to perform the quantitative accelerated life testing (QALT) on tri-axis accelerometer from STM was proposed, with a crude setup to vary the accelerations and temperatures. The purpose of this paper is to employ the QALT procedure on single axis accelerometers from Analog Device and Freescale. Laser-precision apparatus was designed, built, and employed to provide three types of excitations with great accuracy; mechanical (gravitational) test, thermal test and acoustical test. These tests are designed to mimic the operating conditions of the system, where the devices are employed.

Performance of an electronic system can be greatly limited by its internal noise and can be employed as a measure to characterize the effectiveness of such systems. As a result, it is important to investigate electronic noise in semiconductor devices. Electronic noise is due to random events that take place inside electrical devices and the theoretical interpretation of these stochastic events is very important in order to accurately match a noise model to the observed results in experimental studies [1].

The authors performed the low frequency noise measurement (LFNM) technique to study noise characteristics of commercial accelerometers with single and dual axis. In this work, we studied the noise characteristics of a three-axis accelerometer using an improved and sensitive test setup to avoid cross-axis distortion.

The design of CMOS compatible thin ZnO film base, and LiNbO/sub 3/ wafer base, surface acoustics wave (SAW) gas sensors, that are highly selective and sensitive, is described. Furthermore, design and post-CMOS processing fabrication steps that utilises micro-electro-mechanical systems (MEMS) techniques to implement the SAW gas sensor are presented. The Rayleigh wave velocity for various ZnO film thicknesses is simulated and results are presented. The velocity calculation is based on a computer simulation of a multilayer (ZnO/SiO/sub 2//Si) structure that uses wave equations. Simulation results and experimental measurements of SAW sensors with a single layer bulk LiNbO/sub 3/ wafer are shown, and compared. Moreover, results of experimentation and simulation of wave velocity for a yz-cut LiNbO/sub 3/ wafer are shown.

ZnO, a well-known piezoelectric material, is used to develop micro-scale surface acoustic wave (SAW) delay line sensor. In this work, SAW delay line sensors are fabricated employing ZnO films that are deposited by RF sputtering technique. Films are characterized prior to device fabrication by X-ray diffraction (XRD) for film crystalline quality, UV-visible transmission spectroscopy for optical characteristics, and atomic force microscopy (AFM) for surface morphology. Interdigital electrodes producing surface acoustic waves in the hundreds of MHz are developed by photolithography and metallization techniques. SAW delay line sensor device testing, measurement and characteristics on RF sputtered ZnO films are presented and compared.

In this paper we describe the design and implementation of a CMOS surface acoustic wave (SAW) oscillator. The oscillator utilizes surface acoustic wave resonators implemented in both 1.6micron and 0.5micron AMI CMOS process and fabricated through MOSIS. When connected to Pierce oscillator circuits, these resonators are capable of synthesizing frequencies in the range of 400MHz to 1GHz. This paper also addresses the design issues involving codesigning micromachined resonators with CMOS circuitry to optimize the oscillator design

The development of inexpensive and miniaturized SAW gas sensors that are highly selective and sensitive is introduced. These sensors are implemented with micro-electro-mechanical systems (MEMS) in CMOS technology. Since the sensors are fabricated on a silicon substrate, additional signal processing circuitry can easily be integrated into the chip thereby readily providing functions such as multiplexing and analog-to-digital conversion that are needed for integration into a network.

A comparison of synthetic-aperture radar (SAR) sea images generated by a simulation program implementing a two-scale theory and by the Jet Propulsion Laboratory L-band SAR flow in the TOWARD oceanographic experiment is discussed. A subimage cross-correlation technique estimates the best image focus. The sea surface imagery is composed of two scales, a long-wave ensemble and a short-wave ensemble, and both gravity waves. The appropriate two-scale hydrodynamic and electromagnetic scattering approximate models are combined with a model for SAR imaging of a time-variant, extended scene. The resulting model is complicated and generally requires a simulation, which generates the complex, high-resolution SAR image to reveal its full nature. The two-scale theory's predictions agree well with the actual measurements, including the discriminating prediction that the best focus correction is proportional to the long wave's phase velocity. >