Flexible tactile sensor materials based on carbon microcoil/silicone-rubber porous composites

Mechanical and electrical properties of porous composites consisting of spring-shape carbon microcoils (CMCs) and silicone-rubber were investigated. The CMC/rubber porous composites having 71-81% porosity had compressive elastic moduli of 0.04-0.1 MPa which were 2-4% of a composite having the same ingredients without pores. The porous structure gave the composites not only the flexibility but a unique piezoresistivity in a wide compressive strain range. Resistivities of the porous composites increased over 104 times with a compressive strain up to 80%, while those of other porous composites including fibrous or particulate carbon fillers decreased only several tens of percent. CMC/rubber porous composites having such a unique piezoresistivity enabled us to develop a new tactile sensor system.