Highly Stretchable and Sensitive Ti₃C₂T_x MXene/Sodium Alginate/Acrylamide Hydrogel for Flexible Electronic Sensors

Abstract

Flexible sensors require good tensile properties, flexibility, and enough sensitivity for monitoring and transmitting subtle strain changes in motion. Here, the MXene-sodium alginate-acrylamide (MSA) composite hydrogel was synthesized by polymerization of acrylamide (AM), Ti3C2Tx MXene nanosheets, and sodium alginate (SA). Scanning electron microscopy, energy dispersive spectroscopy, and elemental mapping demonstrated a uniform dispersion of Ti3C2Tx MXene nanosheets in the composite hydrogel regime. The strong hydrogen bonding interactions between Ti3C2Tx MXene nanosheets and SA–AM polymers were verified by Fourier transform infrared spectroscopy and differential scanning calorimetry analysis. The prepared M20S2.5A hydrogel had 4350% limited tensile strain and fractured energies up to 359.51 J m–2 and significant hysteresis in cyclic loading–unloading experiments, indicating its excellent energy dissipation performance. The conductivity of the M20S2.5A hydrogel had a good linear response (1300–3500%) with the stretch distance and a fast response time of 0.27 s. At the same time, MSA hydrogels have high sensitivity (GF = 2.31). These advantages allowed it to real-time monitor the random motion of the human body such as throat swallowing, finger bending, and knee flexion and extension. The present study showed great potentials of the MSA hydrogel in flexible wearable devices.