Design and properties of quartz-based Love wave acoustic sensors incorporating silicon dioxide and PMMA guiding layers

摘要

Love wave surface acoustic wave devices are very promising as sensors in gaseous and liquid environments because of their high sensitivity, In this work, two methods of producing the Love wave guiding layer were utilized to fabricate devices based on ST-cut quartz, The methods involved sputter deposition of silicon dioxide films and spin coating of polymethylmethacrylate (PMMA) films. SiO2/ST-cut quartz devices with SiO2 thicknesses up to 7.3 mu m and PMMA/ST-cut quartz devices with PMMA thicknesses up to 1.9 mu m have been manufactured and compared, Mass sensitivity, insertion loss, temperature coefficient of oscillation frequency and frequency noise have been studied as a function of layer thickness. A number of hybrid devices consisting of PMMA film/SiO2 film/ST-cut quartz have also been assembled and evaluated. These devices exhibit higher sensitivity than the SiO2 devices and the PMMA devices produced here.