NEW DESIGN FOR QCM SENSORS IN LIQUIDS

The use of quartz-crystal microbalance (QCM) sensors in liquids for analytical purposes requires a well-designed transducer. Therefore a theoretical model is necessary to characterize the influence of liquid properties like density, viscosity, conductivity and dielectric behaviour. The high damping of the liquid loading results in a large loss of the quartz-crystal quality factor. Special electronics and a suitable sensor cell are necessary to obtain good frequency stability. The paper describes a new device based on an operational transconductance amplifier (OTA) with a very high bandwidth. Experimental results illustrate the ability of the sensor system to detect small amounts of special analytes in liquids.