Design of strain sensors using highly entangled hydrogel: High resolution, large detection range, and low hysteresis

Stretchable strain sensors with high performance are desirable for sports health monitoring, human-computer interaction, and soft machines. Sensors using polyacrylamide hydrogels with long chains have good stretchability and low hysteresis but limited resolution at small deformation. Here, we design stretchable strain sensors using highly entangled polyacrylamide hydrogels with high modulus and low hysteresis. The high modulus ensures the solid behavior of the material, making the elongation at small deformation detectable, and the resolution can be up to 0.2%. The sensor can measure the elongation of elastomers within the range of 200%. The change of relative resistance maintains low hysteresis and is repeatable over tests of 1000 cycles. The hydrogel sensor with water-retaining encapsulation exhibits electrical stability for a long time.