声表面波延迟线振荡器为核心的气体传感器

Vapor Sensors Based on Surface Acoustic Wave Delay Line Oscillators

声表面波(SAW)器件的工作频率随基片表面上的负载质量变化而发生漂移,通常利用这一性质作气相分析与检测,已经有了若干用SAW延迟线器件制成的化学传感器。传感器表面涂着一层有化学选择性的薄膜,这一涂层则在化学分析时有选择地吸收待测气体分子,涂层在吸收了气体后发生一些物理变化,因而这种传感器的灵敏度与SAW延迟线表面上的涂层对气体的吸收量有关。许多实际使用的传感器是用双SAW延迟线组成的,它们集成在一片基体上,并在一个延迟线表面上涂上气体吸附薄膜,而另一个则不涂任何物质。 本文讨论了这种传感器的若干问题,如温度影响、响应时间以及频率变化与气体浓度间关系的非线性。最后提出了在传感器应用时的改进方法与措施。

Surface Acoustic Wave (SAW) device responds to Changes in the mass on its Surface with a shift in frequency and is most frequently used in gas-phase sensing applications.Some chemical sensors have used SAW devices [fabricated in the delay line configuration. A thin overlayer of a chemically selective material serves to collect and concentrate analyte molecules at the sensor's surface by sorption. The sensitivity of this type of sensor is dependent on the amount of vapor sorbe.d and the SAW transducers inherent ability to respond to the physical changes in the overlay film caused by sorption. Many sensor applications use a dual device configuration consisting of two SAW delay lines that have been constructed side by side on the same substrate. One delay line can be coated with the sorptive overlayer While the other delay remains uncoated.Practical problems of the sensors as the influence of temperature, response time, and non-linearity with frequency change-with gas concentration are discussed. Finally, the way to improve the application of the sensor is proposed.