Inkjet material deposition is a promising approach to print multiple functional components for dielectric elastomer (DE) devices. The automatic fabrication process promotes reliable and repeatable results, and allows scaling to a few millimetres, which is advantageous in areas such as microfluidics and optics. We present here the printing and evaluation of novel ink formulae comprising silicone and a conductive filler. Carbon black, the conductive filler, is a popular electrode material. Although it has a relatively high resistance, it has been shown to produce compliant electrodes of good performance for dielectric elastomer actuators (DEA). Carbon black is added to liquid silicone rubber and solvents in order to obtain a solution that can be inkjet-printed. The silicone provides binding of the carbon particles into a soft matrix as well as bonding to the elastomer membrane on which it is printed. Each ink has unique electromechanical properties, e.g. sheet resistances ranging from a few kΩ/sq to MΩ/sq. We can apply different inks to provide conductive electrodes for DEA or piezoresistive components such as the dielectric elastomer switch (DES) - able to locally control charge over DEA - or simple resistor and electrode tracks. We discuss ink behaviours and printed sample components for networks of DEA and combined driving circuitry, all with soft, flexible materials.
Conventional electronics are typically rigid, introducing unwanted stiffness to otherwise entirely soft systems. Emerging soft and stretchable electronics provide a platform for integrating driving electronics in soft robotics and structures. A stretchable electrode having strain-dependent resistance is the dielectric elastomer switch (DES). The DES enables direct control of artificial muscles, or dielectric elastomer actuators (DEA), a popular material in soft robotics. Electromechanically interacting DEA and DES together make up smart actuator networks, with the DES as piezoresistive-charge gates. The DES is a unique stretchable electrode in that it directly couples mechanical strain with a logic state change. We have previously demonstrated logic gates and memory elements using DES/DEA arrays. Performance, particularly speed and cycle life, were limited due largely to acrylic-based, viscoelastic materials and hand-made fabrication process. Here we present computing elements with enhanced performance, comprising silicone membranes and airbrushed silicone-based electrodes. We also demonstrate a new model - a dielectric elastomer digital oscillator. The oscillator provides the timing signal for sequential logic elements, which reduces number of wires and inputs needed for DE circuits. Finally, we also use the mechanosensitive DES to implement adjustable frequency of the DE oscillators.