Piezoelectric Ultra-Stretchable Strain Sensor with Excellent Linearity and Unique Self-Healing Ability

Biomedical monitoring is of great importance to society, as this area directly impacts our daily lives. Wearable strain sensors are essential for the realization of applications in the broad fields of remote healthcare monitoring, soft robots, immersive gaming, among many others. These flexible sensors should be comfortably adhered to skin and capable of monitoring human motions with high accuracy, as well as exhibiting excellent durability. However, it is challenging to develop electronic materials that possess the properties of skin-compliant, elastic, stretchable, and self-healable. Here we show a soft electronic material composed of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA), polyaniline (PANI) and phytic acid (PA) that exhibits ultrahigh stretchability (~1935%), excellent repeatable self-healing ability without intervention (repeating conductivity healing efficiency >98%), and exceptional linearity without calibration. The PAAMPSA/PA and doped PANI emeraldine salt, under ambient conditions, construct a dynamic network of polymer chains crosslinked by hydrogen bonds and electrostatic interactions which enables ultrahigh stretchability and autonomous repeatable self-healing. Sensitive strain-responsive geometric and piezoresistive mechanisms of the material owing to the homogenous and viscoelastic nature provide the sensor with excellent linear responses to omnidirectional tensile strain and bending deformations. It is shown that this electronic material is also scalable and simple to process in an environmentally-friendly manner, paving the way for the next generation flexible electronics.