Pressure responsive resistive material

Abstract

Abstract MATERIALS AND SENSING ELEMENTS HAVING CONTROLLED CHANGES OF RESISTANCE VALUES IN RESPONSE TO PRESSURE ARE PROVIDED BY VOLUMETRICALLY DISPERSING CONDUCTIVE OR PARTIALLY CONDUCTIVE PARTICULATES OF AT LEAST ONE TYPE THROUGHOUT A PREDETERMINED VOLUME. THE PARTICULATE MASS IS FINTIELY BUT MINUTELY COMPRESSIBLE IN AT LEAST ONE DIMENSION, BUT CONFINED IN OTHER DIMENSIONS WITHIN AN ENCOMPASSING STRUCTURE OR BY A BINDER OR MATRIX. THE PARTICLE DISPERSION IS SUCH THAT WITHOUT APPLIED PRESSURE THE ELEMENT, TYPICALLY FORMED IN A RELATIVELY THIN STRATUM, HAS A COMPOSITE RESISTANCE, VALUE DETERMINED BY MULTIPLE CURRENG FLOW PATHS, AND THIS VALUE MAY BE SO HIGH AS TO RENDER THE MATERIAL ESSENTIALY NONCONDUCTIVE. APPLIED OR INCREASED PRESSURE COMPACTS THE PARTICLES SUCH AS TO INCREASE THE NUMBER OF CURRENT FLOW PATHS. INCREASE TO CONTACT AREA BETWEEN PARTICLES AND THEREOFORE THE ARE OF THE CURENT FLOW PATHS, AND ALSO INCREASE INTERNAL STRAINS, WHILE DECREASING THE INTER-PARTICLE CONTACT RESIDENCE AND THE FLOW PATH LENGTHS, ALL THESE FACTORS CONCURRENTLY ACTING TO DECREASE THE RESISTANCE OF THE ELEMENT. THE COMPRESSION AND MOVEMENT ARE VERY LIMITED IN EXTENT, AND THE CURRENT FLOW IS CHANGED IN ESSENTIALLY SOLID STATE FASHION, WITHOUT ARCING OR CROSS-OVER. PARTICULATES, BINDERS AND BUFFERING POWDERS ARE DISCLOSED THAT ARE SUBJECT TO MINIMUM HYSTERESIS EFFECTS AND WEAR. THE RATE OF RESISTANCE CHANGE OF PRESSURE, AND THE RANGE OF RESISTANCE VALUES ARE CONTROLLED AND SELECTED BY VARIATION OF A NUMBER OF FACTORS, INCLUDING THE PROPERTIES AND RATIOS OF THE MATERIALS USED, THE THICKNESS OF THE ELEMENT, THE AREA UNDER COMPRESSION, THE APPLIED VOLTAGE AND THE CONFIGURATION AND SPACING OF COUPLED ELECTRODES.

Inventors

• 👤 R Mitchell

Bibliographic Details