Stretchable porous conductive hydrogel films prepared by emulsion template method as flexible sensors

Conductive hydrogels with stretchability, breathability and long-term stability have attracted increasing attention for the applications in interactive wearable devices, artificial prosthetics, and intelligent robots. In this paper, a stretchable (up to 254 %), well breathable (vapor transmission up to 1.231×10−2 g·cm−2·h−1), and stable conductive (1.21 S/m) hydrogel films (Gel/PPy/Ag) was prepared by gel-template immersion method using gelatin as gel networks, polypyrrole (PPy) and silver (Ag) as conductive reinforcing filler and Span 80 as emulsion template. The film could maintain flexibility and conductivity after stored in an environment of –20 °C or 25 °C for 20 days. The excellent frost resistance and water retention ensured the practical application of the porous organic hydrogel film with environmental adaptability and long-term stability. The strain sensor made from the Gel/PPy/Ag films presented excellent sensitivity (GF reached 2.034), good durability, fast response (0.34 s) and recovery ability (0.36 s). It monitored weak and vigorous human motions effectively and sensitively. The Gel/PPy/Ag flexible electrodes realized the real-time sensitive detection of human Electrocardiogram (ECG) and electromyogram (EMG) signals and precision sensing control of the manipulator arm. The Gel/PPy/Ag hydrogel and the prepared flexible electronic devices have broad application prospects in the field of health monitoring, motion monitoring, operation control and other soft electronic devices.