Ultrasensitive, flexible and dual strain-temperature sensor based on ionic-conductive composite hydrogel for wearable applications

The integration of dual strain-temperature sensing properties into a sensor remains a huge challenge. Sensors prepared with the strain/temperature-sensitive electrically conductive materials achieve the performances, however, the poor stretchability and opacity limit the application. Herein, an ionic-conductive composite hydrogel was prepared via radical polymerization by adding LiCl and glycerol. The hydrogel with superior flexibility and transparency displayed excellent strain-sensitivity of 17.3 in a wide strain range of 1973%. Furthermore, due to the strong ionic hydration and the formation of the strong hydrogen bond interaction, the antifreezing hydrogel showed excellent temperature-sensing performances in a range of -30 ∼ 80 °C, which exhibited a superior thermal-sensitivity of 5.51 %/°C and a high resolution of 0.2 °C in the range of 36.5 ∼ 40 °C. The excellent dual strain-temperature sensing performances make hydrogels promising candidates for flexible sensors with multiple functions and expand the application in human–machine interface and soft robot.