Pressure transducer with conductive polymer bridge

• US 4,852,581 A
• Filed: 12/14/1987
• Issued: 08/01/1989
• Est. Priority Date: 12/14/1987
• Status: Expired due to Term

• Current Assignee: Medex Incorporated (Smiths Group International Holdings Ltd.)
• Original Assignee: Medex Incorporated (Smiths Group International Holdings Ltd.)
• Inventors: Frank, Thomas P.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): Sykes, Angela D.
• Application Number:
  US07/132,014
• Time in Patent Office: 596 Days
• Field of Search: 128/672-673, 128/675, 128/748, 338/3-4, 338/36, 338/42, 73/725, 73/726, 73/727
• US Class Current: 600/485
• CPC Class Codes: G01L 1/2287 constructional details of the strain gauges adjustable resistors H01C10/00
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm

Abstract

A pressure transducer has a thin central portion formed of a molded thermoplastic resin. A conductive polymer forms the resistive elements of a Wheatstone bridge printed and baked onto the molded substrate.

Claims

1. A pressure transducer comprising:

a molded high temperature, thermoplastic substrate having a thin flexible section,

at least one conductive polymer resistor printed on said flexible section,

said resistor changing its resistance when said substrate is flexed.

2. A pressure transducer comprising:

a molded substrate formed from a high temperature thermoplastic material having a thick border and a thin flexible central section,

a resistance bridge formed of conductive polymer resistors printed and baked on said thin central section, said resistors having ends,

and conductors connected to the ends of said resistors.

3. A transducer as in claim 2 in which said conductors are printed on said substrate and leads are connected to said conductors with a conductive epoxy.

4. A transducer as in claim 2 in which said thick border is circular.

5. A transducer as in claim 2 in which said thick border is circular and the center of said central section has a thick integrally-molded boss forming a rigid center.

6. A transducer as in claim 2 in which said thin central section has a thickness in the range of about 5 to 15 mils.