The Potential of Surface Acoustic Wave Devices for the Selective Detection of Trace Amounts of Molecules

Abstract

Chemical Sensors and Biosensors try to mimic the capability of living systems to detect very small amounts of analyte molecules using specific host-guest type of reactions. Recent advances in microelectronic technology have led to a new generation of sensor devices, the piezoelectric microbalances, based on planar microfabrication techniques. They show a very high sensitivity ( up to femtograms ) for detecting molecules which adsorb to the surface of the device and change its resonance frequency with mass loading. All chemical or biological microsensor devices require a surface coating that will interact with the specific chemical or class of chemicals or biomolecule to be detected. The majority of applications have made use of bulk acoustic wave (BAW) devices, usually with an adsorptive coating to provide some degree of selectivity towards the analyte of interest [Glassford]. The oscillation frequency of a BAW device immersed in solution changes with the temperature of the solution, with the specific gravity and conductivity as well as the microviscosity at the interfacial layer, which can be changed by analyte binding.