Direct ink writing of tunnelling graphite based soft piezoresistive pressure sensors

Tunneling based piezoresistive sensors are often utilized for dynamic pressure sensing due to their low cost, ease of fabrication, ability to be printed and integrated with read-out modules. These devices can be subsequently integrated with transistors, actuators and other components towards the development of multifunctional electronic skin (e-Skin), where it is important that sensors exhibit uniform and replicable behavior. This can also help to minimize the need for compensation circuits during long-term use. In this study, direct ink writing of custommade low viscosity graphite ink is used to develop soft piezoresistive pressure sensors. The uniformity of the devices is gauged via the base conductivity and piezoresistive response, both of which exhibit a very good coefficient of variation of 2.21% and 7.1%, respectively. Furthermore, the sensors are sensitive to a wide range of forces from 0-7 N (~3.2 MPa maximum pressure). These devices pave the way towards efficient integration of pressure sensors for object grasping and manipulation due to their small size and bendability.