Micromachined Flow Sensors Enabling Electrocalorimetric and TOF Transduction

A novel thermal flow sensor is presented featuring three spatially separated micromachined silicon-nitride membranes. A thin-film heater is embedded in the central one, while the others carry thermistors. This advanced sensor structure enables two different transduction modes. The electrocalorimetric mode exhibits high resolution and quick response at the expense of high power consumption. For slowly varying flows, the Time-of-Flight mode with low duty-cycles allows for power-saving operation but suffers from less sensitivity and slower response.