A simple and effective testbench for quartz tuning fork characterization and sensing applications

A test and measurement system for the characterization of standard 32 kHz tuning fork crystal based sensors is proposed. A very simple circuit configuration provides for a white noise voltage test signal to be applied to the tuning fork device and to a variable capacitor that, in combination with a differential transimpedance amplifier, allows to detect and amplify the current through the device subtracting the effect of the intrinsic and external stray capacitance. The white noise signal and the output of the transimpedance amplifier are fed to the left and right channels of a PC sound board that provides for signal elaboration and direct extraction of the sensor admittance vs frequency.