Fabrication of piezoresistive devices based on dielectric elastomers via ultrasonic spraying

Soft, flexible and stretchable piezoresistive devices that are able to resemble microelectronic functionalities can advance the development of data processing and soft robotics. In this work, a piezoresistive device composed of a dielectric elastomer actuator (DEA) and a dielectric elastomer switch (DES) is presented. The DES was fabricated via an ultrasonic spraying machine, it is a piezoresistive element that undergoes resistance change when suffering from external mechanical deformation. A piezoresistive ink with carbon black (CB) and a carboxylic acid ester-based dispersant was prepared, and its stability was evaluated by an analytical centrifuge apparatus. It was found that the ink with high stability had a ratio of dispersant to CB equal to or higher than 0.5:1. The ink was further diluted with 50% ethanol and the new resultant formulation could obtain a uniform deposition on the substrate. The piezoresistive performance of the device was studied. The results indicated that the optimized piezoresistance behavior, more than two orders of magnitude change in resistance, was achieved at a printing speed of 240 mm/min and a printing height of 45 mm. Eventually, two devices were connected to build up a multiplexer (MUX) which successfully demonstrated that this novel type of dielectric elastomer (DE) piezoresistive devices could process data like the traditional counterpart.