Miniaturized pressure sensor
First Claim
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1. A miniaturized pressure sensor, comprisinga support body (10) having an upper surface and a depression (12) formed in said surface;
- a diaphragm (14), covering said depression (12) so as to form a closed cavity, said diaphragm being responsive to external pressure by being deflected;
a strain gauge (16) disposed inside said cavity and beneath said diaphragm (14), cooperatively coupled to said diaphragm so as to generate an output signal in response to the deflection of said diaphragm, said strain gauge in at least one of its ends being suspended (18) by said diaphragm.
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Abstract
An entirely surface micromachined free hanging strain-gauge pressure sensor is disclosed. The sensing element consists of a 80 μm long H-shaped double ended supported force transducing beam (16). The beam is located beneath and at one end attached to a square polysilicon diaphragm (14) and at the other end to the cavity edge. The sensor according to the invention enables a combination of high pressure sensitivity and miniature chip size as well as good environmental isolation. The pressure sensitivity for the sensor with a H-shaped force transducing beam, 0.4 μm thick was found to be 5 μV/V/mmHg.
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24 Claims
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1. A miniaturized pressure sensor, comprising
a support body (10) having an upper surface and a depression (12) formed in said surface; -
a diaphragm (14), covering said depression (12) so as to form a closed cavity, said diaphragm being responsive to external pressure by being deflected; a strain gauge (16) disposed inside said cavity and beneath said diaphragm (14), cooperatively coupled to said diaphragm so as to generate an output signal in response to the deflection of said diaphragm, said strain gauge in at least one of its ends being suspended (18) by said diaphragm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 24)
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18. A miniaturized pressure sensor, comprising
a support body having an upper surface and a depression formed in said surface; -
a diaphragm, covering said depression so as to form a closed cavity, said diaphragm being responsive to external pressure by being deflected; a strain gauge attached at one end to said support body inside said cavity and beneath said diaphragm, and at another end suspended by said diaphragm.
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19. A miniaturized pressure sensor, comprising a support body with an evacuated cavity formed therein, a diaphragm forming a sealing cover for said cavity, and a strain gauge disposed inside said cavity and coupled to the support body and said diaphragm such that a deflection of said membrane caused by a pressure exerted thereon causes a detectable change in strain in said strain gauge.
- 20. A miniaturized pressure sensor, comprising a diaphragm responsive to pressure by being deflected, and a freehanging strain gauge responsive to strain by yielding an electrical output signal, said strain gauge being suspended at one end by said diaphragm, such that a deflection of said diaphragm causes a detectable change in strain in said strain gauge.
- 22. A miniaturized pressure sensor, comprising a support body with an evacuated cavity formed therein, a diaphragm forming a sealing cover for said cavity, and a force transducing beam provided inside said cavity and beneath said diaphragm, and suspended by said diaphragm in at least one end of said beam by a suspension element having a finite length.
Specification