Wearable Stretchable Dry and Self‐Adhesive Strain Sensors with Conformal Contact to Skin for High‐Quality Motion Monitoring

Abstract Wearable stretchable strain sensors can have important applications in many areas. However, the high noise is a big hurdle for their application to monitor body movement. The noise is mainly due to the motion artifacts related to the poor contact between the sensors and skin. Here, wearable stretchable dry and self‐adhesive strain sensors that can always form conformal contact to skin even during body movement are demonstrated. They are prepared via solution coating and consist of two layers, a dry adhesive layer made of biocompatible elastomeric waterborne polyurethane and a sensing layer made of a non‐adhesive composite of reduced graphene oxide and carbon nanotubes. The adhesive layer makes the sensors conformal to skin, while the sensing layer exhibits a resistance sensitive to strain. The sensors are used to accurately monitor both small‐ and large‐scale body movements, including various joint movements and muscle movements. They can always generate high‐quality signals even on curvilinear skin surface and during irregular skin deformation. The sensitivity is remarkably higher while the noise is saliently lower than the non‐adhesive strain sensors. They can also be used to monitor the movements along two perpendicular directions, which cannot be achieved by the non‐adhesive strain sensors.