Fast impedance analyzer interface with direct-sampling-technique for highly damped resonant gas sensors

In order to acquire multiple information about highly damped resonant gas sensors, such as frequency shift and damping figure, a compact impedance analyzer interface with direct-sampling-technique (DST) has been developed. DST allows accurate signal detection, good noise rejection by digital signal processing and very short measurement periods. The compact impedance analyzer is well suited for process control applications and can be employed for any sensor systems based on impedance spectroscopy by adapting the input stage of the interface. As an example, a CeO₂ coated langasite BAW resonator acting as high temperature gas sensor is presented, which acts as microbalance for measuring changes in conductivity and mechanical properties of the metal oxide sensor film