Pressure activated switching device
OwnerLester E. Burgessinventor
Life of this patent
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Abstract
A pressure sensitive sparkless switching device includes a layer of piezoresistive cellular polymer foam, at least two conductive layers, and an insulative spacer element having at least one opening. When pressure is applied to the device the piezoresistive foam disposes itself through the opening of the spacer element and makes electrical contact between the conductive layers. The resistance of the piezoresistive foam varies with the amount of pressure applied to provide an analog as well as on-off function. The device may also provide multiple switching, and shear detection capabilities.
Claims15
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.
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.
Dependencies are inferred from the claim text.