Flexible piezocapacitive and piezoresistive force and pressure sensors

摘要

Flexible force/pressure sensors for producing electrical output signals proportional to forces or pressures exerted on the sensor include a thin, elastically deformable foam pad laminated between a pair of electrically conducive fabric sheets. A piezocapacitive embodiment of the sensor utilizes an elastically deformable perforated open-cell polyurethane foam pad preferably saturated with glycerin to increase the capacitance of the sensor. The piezocapacitive sensor section is preferably stacked onto a piezoresistive section having a second open-cell foam pad containing piezoresistive carbon particles to form a hybrid piezocapacitive/piezoresistive sensor. A third, “leaky dielectric” embodiment of a sensor includes a single open-cell foam pad which contains both a dielectric liquid and conductive particles. A low frequency such as d.c. to a few hertz is applied to a sensor to determine piezoresistive response of the sensor to forces or pressures and a higher frequency such as 30 KHz is applied to determine piezocapactive response.

主权项

1. A pressure sensitive sensor for producing an electrical output signal proportional to pressure exerted on said sensor, said sensor comprising;
a. a first, electrically conductive base lamination which has an outer planar surface and an inner electrically conductive planar surface, b. a second, electrically conductive cover lamination which has an outer planar surface and an inner electrically conductive planar surface which confronts said inner conductive surface of said base lamination, and c. a pad positioned between said first and second laminations, said pad having a first outer surface in contact with said inner conductive surface of said base lamination and a second outer surface in contact with said inner surface of said cover lamination, said pad having an electrical property which is proportional to a force or pressure couple exerted normally on outer surfaces of said base lamination and said cover lamination sufficient to decrease spacing between said inner conductive surfaces of said first and second laminations.