SMD pressure and flow sensor for compressed air in LTCC technology with integrated electronics

In this work, we present an integrated flow / pressure / temperature multisensor in LTCC (low- temperature co-fired ceramic) technology designed for diagnostics monitoring of standard industrial compressed air circuits and devices, such as valves and actuators. The pressure sensor is based on a membrane carrying a thick-film piezoresistive Wheatstone bridge. Flow is sensed using the constant- temperature anemometric principle, with the sensing thermistors placed in a fluidics channel, which also comprises similar thermistors for temperature sensing. All three sensors are integrated into a single surface-solderable LTCC unit, with the solder fulfilling the roles of mechanical fastening, electrical connectivity and fluidic sealing. In this work, the flow-sensing part is demonstrated, and possible improvements in efficiency outlined. Key words: multisensors, flow, pressure, temperature, LTCC