Direct-write of multi-layer tactile sensors

Direct-write of piezoresistive photopolymers is regarded as a promising means to produce compliant tactile sensors. In this work, a multi-layer compliant tactile sensor was developed using a hybrid manufacturing process including soft molding, micro-dispensing and photopolymerization processes. The working principle of the suggested sensor is to detect changes in resistance as it is deformed. A compliant skin structure was built layer-by-layer using a soft polyurethane material to cover the piezoresistive sensing elements. These sensing elements were created from stretchable photocurable conductive carbon nanotube (CNT)/prepolymer nanocomposites, which were deposited by the micro-dispensing process within the polyurethane skin layers and cured during the molding process. The fabricated tactile sensor consists of two layers of sensing elements within the skin structure; there are eight stretchable straight wires in each layer. The wires in the second layer were orthogonally placed on top of the first layer so that the sensor can detect various external forces/motions in two dimensions. The fabricated sensor was characterized by several experiments such as position, and 2D pattern detection. Finally, it is concluded that the tactile sensor using the hybrid manufacturing method and materials is promising for various applications such as robotics, prosthetics, and wearable electronics.