A 1200-atmosphere bulk-type all-silicon pressure sensor

Distinct from conventional diaphragm-type pressure sensors, a bulk-type silicon-based pressure sensor is proposed and demonstrated. External hydrostatic pressure acting on the sensor is converted to biaxial compression inside an all-silicon encapsulated vacuum cavity, and measured using four piezoresistors oriented to optimally utilize the anisotropy of silicon piezoresistance. Limited only by the test setup but intrinsically capable of a much higher pressure rating, the sensor has been tested to 120 MPa (around 1200 atmospheres). Containing no fragile movable micro-structures and constructed almost entirely of silicon using conventional micro-fabrication techniques, the self-contained sensor is robust and potentially low-cost.