LTCC/PZT differential pressure sensor utilizing ultrasonic wave resonator

In the paper technology and properties of a differential pressure sensor utilizing ultrasonic waves are presented. The device consists of a LTCC (Low Temperature Co-fired Ceramics) membrane with PZT (Lead Zirconate Titanate) active layer with two interdigitated transducers (IDTs). The sensor is a completely ceramic structure equipped with two gas inlets, hence measurements of differential pressure up to 20 kPa is possible. The properties of the sensor are determined in resonator mode, where frequency shift is observed during pressure and temperature changes. The sensor exhibits sensitivity of about -400 Hz/kPa and a thermal drift of about -2000 Hz/°C. Electronic circuits: amplifier and frequency counter are described. The thermal drift is compensated using an integrated thick-film PTC (positive temperature coefficient) resistor and software correction.