Study of a Surface Acoustic Wave Microsensor for Gas Detection

目前存在对准确的、可靠的微型传感器，可以与观察者通信与可能在分子水平或十亿分之一到万亿分之一范围内的过程相关的数据。声表面波(SAW)技术是实现微传感器最有吸引力的方法之一。声表面波气体微传感器基本上由双声表面波延迟线组成。每条线路被配置为振荡器，其中一条线路的传播路径包含选择性吸收膜，而另一条线路是未涂覆的基准。吸附在薄膜上的气体引起的相位延迟变化导致频率漂移，频率漂移与气体浓度成正比。缅因州大学正在进行一项跨学科的工作，包括声表面波器件的理论、设计、制造和测试以及表面的物理和化学，以实现这种传感器的潜力。本次更新项目的目的是继续进行声表面波气体微传感器的实验和理论研究。所使用的传感膜是三氧化钨(WO_3)，被传感的气体是硫化氢(H_2S)。为了研究和优化传感器特性，如选择性、灵敏度、工作范围、传感器信号、响应时间、恢复时间、重复性和老化，正在使用微观和宏观实验工具。

Currently a need exists for accurate, dependable microsensors which can communicate to the observer data associated with processes which may be at the molecular level or the parts per billion to trillion range. Surface acoustic wave (SAW) technology offers one of the most attractive methods to realize the microsensor. The SAW gas microsensor basically consists of twin SAW delay lines. Each line is configured as an oscillator and the propagation path of one contains a selectively sorbent film while the other is the uncoated reference. Phase delay changes induced by the gas sorbed on the film results in frequency shifts which are directly proportional to the gas concentration. An interdisciplinary effort which includes the theory, design, fabrication and testing of SAW devices and the physics and chemistry of surfaces is ongoing at the University of Maine to realize the potential of this sensor. The purpose of the present renewal project is to continue the ongoing experimental and theoretical study of the SAW gas microsensor. The sensing film being used is tungsten trioxide (WO3) and the gas being sensed is hydrogen sulfide (H2S). Microscopic and macroscopic experimental tools are being used in order to study and optimize sensor properties such as selectivity, sensitivity, operating range sensor signature, response time, recovery time, reproducibility and aging.