Design and Fabrication of Passive Wireless SAW Sensor for Pressure Measurement

Abstract

This paper mainly presents the design and fabrication of a TDMA (time division multiple access) passive wireless pressure sensor using 2.45 GHz surface acoustic wave (SAW) delay lines. The SAW pressure sensor consists of two LiNbO 3 substrates. The first layer is a pressure-detective thin substrate, on which an interdigital transducer (IDT) and reflectors are fabricated. The second layer is a support substrate, in which a reference pressure cavity is etched. These two substrates are directly bonded. The pressure measurement was successfully demonstrated in a pressure range of 20~280 kPa with good repeatability. In addition, the influence of a tire on the wireless interrogation of the sensor was investigated. Automobile tires have little negative influence on wireless communication, at least if they do not rotate.

Revolution of Sensors in Micro-Electromechanical Systems

“…6) Because the SAW is transmitted on a diaphragm whose deformation depends on pressure, the time delay of the SAW reflected at reflector 4, t 4 , depends on the pressure, which has lead to the development of pressure monitoring systems based on this principle. 7) Reflectors 1-3 are used to obtain temperature Cavity width 2.35μm Diaphragm thickness 6.85μm information and compensate temperatures. The graph in Fig.…”