A Microdischarge-Based Pressure Sensor Fabricated Using Through-Wafer Isolated Bulk-Silicon Lead Transfer

This paper presents a microfabricated sensor that uses electrical microdischarges to sense the deflection of a diaphragm under applied pressure. The sensor responds by redistributing electron current of pulsed microdischarges between one cathode (<inline-formula> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula>), a reference anode (<italic>A1</italic>), and a deflecting anode (<italic>A2</italic>), all of which are located in a cavity under the diaphragm; the differential anode current indicates the applied pressure. In this paper, the sensor is monolithically fabricated from a single silicon wafer, using a combination of surface micromachining and through-wafer isolated bulk-silicon lead transfer (TWIST) technology. The TWIST technology provides lead transfer into the sealed cavity as well as backside contacts, allowing miniaturization of the device footprint and surface mount assembly within systems. The active footprint of the complete sensor measures <inline-formula> <tex-math notation="LaTeX">$300\times 300 \,\,\mu \text {m}^{2}$ </tex-math></inline-formula> in size, making it the smallest sealed microdischarge-based pressure sensor reported to date. The normalized differential current from the anodes monotonically increases from −0.7 to 0.2 as the external pressure increases from 1 to 8 atm. [2017–0274]