Claims
- 1. A piezoresistive material, which comprises:
- an expanded cellular polymeric foam matrix having embedded therein a conductive filler which includes a conductive powder and conductive fibers said expanded cellular polymeric foam matrix having an electrical resistance which decreases in response to compression caused by mechanical pressure applied thereto.
- 2. The piezoresistive material of claim 1 wherein said conductive powder is selected from the group consisting of powdered metal, carbon black, powdered graphite and combinations thereof.
- 3. The piezoresistive material of claim 1 wherein said conductive fibers are selected from the group consisting of metal fibers, graphite fibers, and combinations thereof.
- 4. The piezoresistive material of claim 1 wherein said expanded cellular polymeric foam matrix is a closed cell foam.
- 5. The piezoresistive material of claim 1 wherein said conductive powder comprises particles ranging from about 0.01 to about 25 microns in diameter.
- 6. The piezoresistive material of claim 1 wherein said conductive fibers range from about 0.1 to about 0.5 inches in length.
- 7. The piezoresistive material of claim 1 wherein the polymeric foam matrix includes a deskinned surface.
- 8. A method for making a piezoresistive material which includes the steps of:
- a) combining a conductive filler with an expandable resin, wherein the conductive filler includes a mixture of conductive powder and conductive fibers;
- b) combining a foaming catalyst with the combination of expandable resin and conductive filler; then
- c) expanding, gelling and setting the expandable resin to form a piezoresistive cellular polymeric foam matrix.
- 9. The method of claim 8 wherein the conductive powder is selected from the group consisting of powdered metal, carbon black, powdered graphite and combinations thereof.
- 10. The method of claim 8 wherein the conductive fibers are selected from the group consisting of metal fibers, graphite fibers and combinations thereof.
- 11. The method of claim 8 wherein the cellular polymeric foam matrix comprises an open cell foam.
- 12. The method of claim 8 wherein the cellular polymeric foam matrix comprises a closed cell foam.
- 13. The method of claim 8 wherein the conductive fibers range from about 0.1 to about 0.5 inches in length.
- 14. The method of claim 8 further comprising the steps of:
- applying a cloth to the expandable resin prior to expanding and gelling the expandable resin; and
- deskinning the piezoresistive polymer foam matrix after expanding and gelling the expandable resin by removing the cloth.
- 15. The method of claim 8 wherein the expandable resin is a silicone.
Parent Case Info
This is a divisional of application Ser. No. 08/429,683 filed Apr. 27, 1995 now U.S. Pat. No. 5,695,859.
US Referenced Citations (53)
Foreign Referenced Citations (5)
Number |
Date |
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0167341 |
Jan 1986 |
EPX |
0293734 |
Dec 1988 |
EPX |
1942565 |
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Divisions (1)
|
Number |
Date |
Country |
Parent |
429683 |
Apr 1995 |
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