Construction of strain responsive Ti-containing carboxymethyl cellulose hydrogel with transitional coordination...

Due to marvelous sensitivity and flexibility, conductive hydrogels are popularly used as strain sensors in intelligent skin and wearable electronic devices fields. However, hydrogel tends to be destroyed after long-term use or in accident, leading to performance degradation. Herein, we developed an environmental-friendly Ti-containing conductive hydrogel. The hydrogel network was constructed via a simple two-step method with coordination reaction and amidation reaction based on a metal ion precursor from transitional coordination. The synergies of reversible metal coordination bonds and dynamic hydrogen bonds endowed the hydrogel with excellent self-healing properties (3 h, 93.66 %), tensile properties (136.46 kPa), compression properties (1.122 MPa), and anti-fatigue performance. At the same time, the hydrogel showed excellent self-adhesion, even underwater. Due to Ti⁴⁺, electrical conductivity of the hydrogel was visibly enhanced (σ = 25.64 mS·cm^-1), which resulted in fast response (TS [time sensitivity] = 24.78 s^-1) and short recovery time (153 ms). As a flexible strain sensor, the hydrogel with stable conductivity and high sensitivity could precisely detect and distinguish a series of human motions, even different letter pronunciations. These remarkable features make it a promising application in the fields of intelligent skin and wearable electronic devices.