Tactile sensor integrated dielectric elastomer actuator for simultaneous actuation and sensing

Dielectric elastomers (DE) are a subgroup of electroactive polymers which may be used as soft transducers. Such soft transducers exhibit high energy density and silent operation, which makes them desirable for life-like robotic systems such as a robotic hand. A robotic hand must be able to sense the object being manipulated, in terms of normal and shear force being applied, and note when contact has been achieved or lost. To this end, a dielectric elastomer actuator (DEA) with integrated tactile sensing has been developed to provide simultaneous actuation and sensing. The tactile sensing dielectric elastomer actuator consists of a unimorph-type structure, where the active portion is a laminate of alternating DE and electrode material which expands under applied voltage, and the sensing portion is a stiffer sensing dielectric elastomer which has no electrical connection to the active portion. Under applied voltage, the deformation of the active portion expands but is constrained on one side by the sensing portion, resulting in bending actuation. The sensing portion is a DE with electrodes patterned to form 2x2 capacitive sensing arrays. Dome-shaped bumps positioned over the sensing arrays redistribute tactile forces onto the sensor segments, so that measurement of the capacitance change across the array allows for reconstruction of magnitude and direction of the incoming force.