Flexible, self-powered and multi-functional strain sensors comprising a hybrid of carbon nanocoils and conducting polymers

The development of flexible and stretchable multi-functional sensors addresses the requirements for applications in fields of electronic skins, artificial intelligence, and health/structure monitoring. Here, we fabricated a novel self-powered strain-temperature dual-functional sensor based on composite films of carbon nanocoils (CNCs) and a conductive elastomeric blends of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and waterborne polyurethane (WPU). Owing to the high stretchability of helical-structured CNCs, high elasticity of WPU and multiple interfacial contacts between the conducting constitutes, the sensor exhibited a broad strain detection range of 0–50% and a high sensitivity with gauge factor (GF) of 25. Based on the Seebeck effect arising from the conducting polymer of PEDOT:PSS, the sensor-enabled both detection of temperature changes and strain deformations at a self-powered circumstance. To demonstrate its practical application as a wearable device, the senor was directly attached to the human skin. It not only detected subtle human motion and strain stimuli but also could distinguish the stimuli from either a warm or a cold objective by telling the difference in their temperature signals. This is the first time that the CNC-based composites are developed for use as a multi-functional sensing medium. Our self-powered strain-temperature dual-functional sensor demonstrates great potential in flexible devices and e-skin applications.