Measuring and testing – Fluid pressure gauge – Diaphragm
Reexamination Certificate
2001-08-06
2003-02-25
Oen, William (Department: 2855)
Measuring and testing
Fluid pressure gauge
Diaphragm
C029S025350
Reexamination Certificate
active
06523415
ABSTRACT:
FIELD OF INVENTION
The present invention relates to pressure transducers and more particularly to an improved high pressure piezoresistive transducer which is suitable for use in hostile environments and a novel, advantageous method for making the same.
BACKGROUND OF THE INVENTION
Kulite Semiconductor Products, Inc., the assignee herein, has previously made and patented a method for fabricating high pressure piezoresistive transducers using both longitudinal and transverse piezoresistive coefficients U.S. Pat. No. 5,702,619, entitled “Method of Fabricating a High-Pressure Piezoresistive Transducer”, filed Sep. 30, 1996, and assigned to the assignee herein, the entire disclosure of which is hereby incorporated by reference. Therein, a basic sensor is formed from a piece of single crystal silicon to which sensors are dielectrically bonded on one surface and the other surface of the silicon is bonded to a glass support member. In those structures the piezoresistive elements were formed on the surface of the transducer that is directly exposed to the pressure media. Additionally, electrical contacts and lead wires are also exposed to the media.
This structure is undesirable in some situations, where exposure of the piezoresistive elements, electrical contacts and lead wires to the media shortens the life expectancy of the pressure transducer. Accordingly, it is an object of the present invention to provide a high pressure transducer less sensitive to the media.
SUMMARY OF INVENTION
A pressure transducer including: a silicon substrate including: a first surface adapted for receiving a pressure applied thereto, an oppositely disposed second surface, and a flexing portion adapted to deflect when pressure is applied to the first surface; at least a first sensor formed on the second surface and adjacent to a center of the flexing portion, and adapted to measure the pressure applied to the first surface; at least a second gauge sensor formed on the second surface and adjacent to a periphery of the flexing portion, and adapted to measure the pressure applied to the first surface; a glass substrate secured to the second surface of the silicon wafer.
REFERENCES:
patent: 4578735 (1986-03-01), Knecht et al.
patent: 5702619 (1997-12-01), Kurtz et al.
Bemis Andrew
De Weert Joseph Van
Kurtz Anthony D.
Nunn Timothy
Duane Morris LLP
Kulite Semiconductor Products Inc.
Oen William
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