Shear and Normal Strain Sensing with Electroactive Polymer Composites

Deformation induced variations in dielectric properties of an elastic material is called electrostriction. This effect can be detected using capacitance measurements and employed for sensing shear and normal strains. Almost any solid dielectric can be used as a sensing medium, but electroactive polymeric composites present a unique advantage. A composite's structure can be locally micro-tailored and optimized for a given sensing application by exposing liquid polymeric suspensions to an electric field and curing the obtained structure. A single plane sensor configuration for shear and normal loads is analyzed. Such a design has no moving electrodes, can be implemented using surface micromachining and supplied with on-chip electronics. Advantages of electroactive polymeric sensors include: intrinsic sensitivity to shear strain, robustness and flexibility, high tolerance to overloads, a large selection of candidate material for specific applications, simplicity in the manufacture, and operation and potential for miniaturization.