Design and operation of silver nanowire based flexible and stretchable touch sensors

In recent years wearable devices have attracted significant attention. Flexibility and stretchability are required for comfortable wear of such devices. In this paper, we report flexible and stretchable touch sensors with two different patterns (interdigitated and diamond-shaped capacitors). The touch sensors were made of screen-printed silver nanowire electrodes embedded in polydimethylsiloxane. For each pattern, the simulation-based design was conducted to choose optimal dimensions for the highest touch sensitivity. The sensor performances were characterized as-fabricated and under deformation (e.g., bending and stretching). While the interdigitated touch sensors were easier to fabricate, the diamond-shaped ones showed higher touch sensitivity under as-fabricated, stretching or even bending conditions. For both types of sensors, the touch sensitivity remained nearly constant under stretching up to 15%, but varied under bending. They also showed robust performances under cyclic loading and against oxidation.