Ultrahigh-strength PVA–SNF@TA hydrogel with multifunctionality applied as strain and pressure sensor

Conductive hydrogel flexible sensors have attracted widespread attention in the field of wearable electronic devices, which typically possess the properties of stretch resistance, moisture retention, antifreeze, adhesion, and self-healing. Herein, a silk nanofiber–tannic acid (SNF@TA) is successfully introduced into a polyvinyl alcohol (PVA) hydrogel to prepare a rigid and adhesive PVA–SNF@TA organohydrogel, exhibiting good mechanical strength (up to 365 kPa) and excellent self-healing properties. Due to the presence of conductive ions and ethylene glycol, the PVA–SNF@TA organohydrogel presents high sensitivity and cold resistance (− 18 °C). Moreover, the PVA–SNF@TA organohydrogel maintains a good transparency of 91% and ultraviolet filtration capacity. A strain sensor made of PVA–SNF@TA organohydrogel has good adhesion and accurate sensing signals. Generally, the designed sensor can significantly monitor small deformations, such as frowning, blinking, smiling, and swallowing motions, showing an impressive sensitivity (gauge factor 1.094) and stable (1000 stretching cycles) variable sensing characteristics. More specifically, a pressure sensor consisted of a PVA–SNF@TA organohydrogel cylinder keeps good sensing stability, thereby desirably detecting different large movements of the human body (finger pressing, walking and running). Our work can offer a broad avenue for the advanced architecture of functional hydrogel materials, which has great potential in the field of human exercise and health monitoring. Graphical abstract