Thermal enhancement of gelatin hydrogels for a multimodal sensor and self-powered triboelectric nanogenerator at low temperatures

Conductive hydrogels always suffer from weak mechanical capabilities, low adhesion, and lack of antifreeze performance, which seriously restrict their application in flexible wearable devices at low temperatures. To address these problems, a thermal enhancement strategy was creatively proposed to prepare PEDOT:PSS-gelatin-based (CHGP) hydrogels, which achieved excellent mechanical properties (tensile strength ≈ 7.38 MPa and strain ≈ 150%), good adhesion properties (adhesion strength ≈ 27.8 kPa), and the lowest freezing point (− 51.7 ℃) compared to other reported gelatin-based hydrogels. It was demonstrated that the data monitored by the CHGP-based multimodal sensors at − 25 ℃ and 25 ℃ have high consistency, which proved the sensors’ stability in sensing and monitoring highly sensitive strain and humidity. Furthermore, assembled with VHB tape, a self-powered triboelectric nanogenerator (C-TENG) was designed as a low-temperature monitoring sensor, which can monitor not only body or environment temperature but also human movement without being affected by humidity. C-TENG has the ability to monitor the vital signs and mobility of users at low temperatures to ensure the safety of outdoor workers. Therefore, this study provides a useful strategy for preparing antifreeze hydrogel-based flexible wearable devices with low-temperature monitoring functions.