Highly sensitive MXene-enhanced polyacrylamide/ carboxymethyl cellulose double-network hydrogels with wide operation range for wearable electronics

Flexible sensors based on double-network (DN) hydrogels have become a research hotspot for wearable sensors. However, developing hydrogel-based strain sensors with high tensile properties, sensitivity, and wide detection range remains a great challenge. Herein, a novel highly stretchable, sensitive, and durable strain sensor based on MXene-enhanced polyacrylamide/carboxymethyl cellulose double-network hydrogel (PCM) was prepared, where PAM served as the rigid backbone, while CMC mainly acted as a flexible sub-network structure. MXene was utilized to enhance the mechanical properties of the hydrogel via tight hydrogen bonds between its surface functional groups and the chains of PAM and CMC, while also being applied to build a conductive path in the system. As a result, the prepared hydrogel-based strain sensor featured a wide detection range (0–500%), quick response time (120 ms for loading time and 190 ms for unloading time), high sensitivity (a gauge factor of 16.33), great toughness, and excellent stability. These advantages enable the prepared sensor to be used in dynamically monitoring human movements, such as joint bending, and performing handwriting recognition. This work provides potential development, research and application of double-network flexible hydrogel in wearable materials.