Research On Environmental Sensors Based On Surface Acoustic Wave Resonator Devices

Surface acoustic wave(SAW)devices are a common type of micro-nano scale devices and are mostly used in communication and sensing fields.In communication applications,because of their excellent frequency filtering characteristics,low cost,consistent process,high integration and other characteristics,surface acoustic wave filters and duplexers are widely used in smart phones and other electronic products among the RF front-end module.In sensing applications,due to their high resonant frequency and relatively stable performance,SAW sensors can be used on measurement of temperature,humidity,pressure,substance concentration,and other physical quantities.These quantities can be easily converted to the resonant frequency shift which can be read out more conveniently.In this paper,theory and process of SAW devices are studied to improve the overall performance,and applications and extensions are made in multiple environmental sensing fields.First,the background of SAW is introduced in this paper,then the working principle,key indicators,modeling simulation,process preparation,test analysis of SAW devices are also described.The main performance indicators of SAW devices include resonant frequency,quality factor,temperature coefficient and others.These indicators are usually determined by the characteristics of piezoelectric substrate materials and process factors together.In this paper,high-performance SAW resonator devices are fabricated by optimizing the structure of the substrate material and improving the micro-nano processing technology.Then,in this paper,SAW devices are used on sensing applications including several environmental subdivisions such as temperature,biochemistry,and particulate matter.Wherein for temperature sensing,the portable sensing system comprises a SAW chip and a frequency readout circuit chip.The system is free from dependence on conventional network analyzer and probe station,and still achieves a high resolution and rapid measurement.For biochemical sensing,the concentration of microcystin,an important contaminant in the water source,was measured using a love wave-based SAW device.The detection sensitivity can meet the actual needs.For particle sensing,a test system including particle source,SAW device,and calibration equipment was preliminarily constructed,and basic test and analysis was conducted.Finally,this article summarizes and makes prospect of the research work.This work is mainly focused on high-performance SAW resonator devices and their applications in various fields of environmental sensing fields.SAW devices in communication applications are limited by factors such as higher frequency bands and higher performance requirements,therefore with limited room for expansion.In the field of sensing,SAW devices still have great potential.According to actual needs,different types of SAW devices are developed.Combining the SAW devices and peripheral component to build sensor system,is still an important and promising research.