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A silicon-based bulk-type pressure sensor capable of measuring pressure up to 200 MPa at temperature up to 175 oC is realized and characterized. Hydrostatic pressure acting on the sensor is converted to anisotropic biaxial compression inside an encapsulated vacuum cavity, and measured using two pairs of piezoresistors oriented to optimally utilize the anisotropy of silicon piezoresistance on (110)-oriented substrate. It is also possible to realize the sensor on a conventional (001)-oriented substrate, with the stress-symmetry broken by reducing the biaxial stress field on one pair of the piezoresistors to a uniaxial stress field.

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.