Crack-based hydrogel strain sensors with high sensitivity and wide linear range.

[Display omitted] • The cracking behavior of a double-network hydrogel has been studied. • Excellent sensitivity (GF = 2.2) and high linear working range (0–250 % strain) are obtained. • Crack from network ruptures boosts sensor sensitivity. • The crack hydrogel shows outstanding performance for detecting both large and small strain of human body. Recently, owing to their high sensitivity, spider-inspired crack strain sensors have received considerable attention. However, their short linear range leads to severe limitations in their application in sports health monitoring. Herein, we fabricated a cracked hydrogel strain sensor with a wide linear range using κ-carrageenan and polyacrylamide. This crack hydrogel strain sensor has a wide linear range (ε = 250 %) and excellent linearity (R2 ≈ 0.999) while ensuring high sensitivity (gauge factor GF = 2.2). Moreover, this sensor is sensitive to small vibration signals. We compared it with a traditional hydrogel strain sensor and analyzed how crack appeared. Finally, we presented the application of this sensor in human health monitoring and detection of multiaxial strains. [ABSTRACT FROM AUTHOR]