Stretchable, sensitive, and environment-tolerant ionic conductive organohydrogel reinforced with cellulose nanofibers for human motion monitoring

Conductive hydrogel (CH) strain sensors have made significant progress in wearable electronic products in recent years. However, the use of aqueous solvents as the dispersion medium in CHs largely limits the scope of applications of CHs and impedes the combination of the mechanical properties and ionic conductivity, which is urgently desired to be addressed. Herein, a simple one-pot preparation of anti-freezing, anti-drying ionic CHs with high stretchability (up to 869%), toughness (6.60 MJ/m3), and Young's modulus (0.56 MPa) was proposed. These CHs consist of polyvinyl alcohol, tannic acid, and sodium chloride dispersed in a solvent consisting of glycerol and cellulose nanofiber suspension. The thus-synthesized CHs exhibit good ionic conductivity (~ 0.86 S/m) and strain sensitivity (gauge factor of 8.54). The organohydrogel possesses a sensitive strain sensing capability and a wide-working temperature range (−50 °C to 60 °C), and good stability (30 d in room-temperature) to detect human movement, such as large (joint movement) and subtle movements (voice in the throat). These advantages allow organohydrogel sensors to show great potential for electronic skin, personal healthcare, and flexible wearable devices.