AN EXPERIMENTAL-STUDY OF LOVE-WAVE ACOUSTIC SENSORS OPERATING IN LIQUIDS

It has been shown that properly designed Love-wave acoustic sensors ar e very promising for sensing in gaseous and liquid environments becaus e of their high sensitivity. Since Love-wave devices do not incur a ra diative loss when used in a liquid, they have many potential applicati ons in biosensing. We have successfully manufactured a range of 40 mu m wavelength Love-wave devices based on SiO2/ST-quartz, with the SiO2 thickness ranging from 0 to 7.3 mu m. The relationship of the mass-loa ding sensitivity to the thickness of the SiO2 layer has been obtained experimentally. High sensitivity (greater than or equal to 300 cm(2) g (-1)) is achieved at an SiO2 thickness between 3.5 and 6.5 mu m. The L ove-wave oscillators have operated efficiently in various liquids with excellent stability and low noise. In this paper, we report the exper imental results for the devices operating in various liquids. The mass sensitivity, insertion loss, oscillation frequency stability, noise l evel, liquid viscous loading and acoustoelectric coupling have been st udied. The influence of the thickness of the SiO2 layer an some of the se properties has also been investigated.