Fig. 1 SEM images of sandwich-like Ti3C2Tx/CNT layers[55]

Fig. 2 Surface SEM images of the Ti3C2Tx/CNT film at various stretching states during the first strain-release cycle[55]

Fig. 3 (a) Schematic of the fabrication process for the bioinspired Ti3C2Tx-AgNW-PDA/Ni2+ sensor fabricated through the screen-printing method; (b) Schematic illustration of the structures for the “brick” materials (Ti3C2Tx and AgNWs) and “mortar” material (PDA/Ni2+); (c) Schematic illustration of the Ti3C2Tx-AgNW-PDA/Ni2+ sensor based on the “brick-and-mortar” architecture[56]

Fig. 4 Electromechanical properties of M-hydrogel composite and mechanisms Electrical response of M-hydrogel to (a) tensile strain and (b) compressive strain, with insets showing the corresponding GFs; Scanning electron microscopy (SEM) images of M-hydrogel surface (c) before and (d) after stretching; (e-f) Schematic illustration for the mechanism of the electromechanical responses from M-hydrogel[58]

Fig. 5 (a) Schematic diagram of the HF18 h-d20 min-Ti3C2Tx conductive film at various stretching states during the first stretching-releasing cycle. Top-view SEM images of (b) HF6 h-d3 h-Ti3C2Tx-, (c) TMA-Ti3C2Tx-, and (d) HF18 h-d20 min-Ti3C2Tx-based strain sensors in the maximum tensile state[15]

Fig. 6 (a) Working micromechanism and (b) the equivalent circuit diagram of MXene-material for piezoresistive sensor[59]

Fig. 7 (a) Schematic illustration of fabrication of MX/rGO aerogel, (b) fabrication of MX/rGO aerogel-based sensor and (c) the sensing mechanism[60]

Fig. 8 SEM images and schematic structures of (a) C-MX/CNC and (b) C-CNC; Schematic elasticity mechanisms of (c)C-MX/CNC and (d) C-CNC

Fig. 9 Schematic illustrations of fabrication procedure of (a) MXene-sponge and (b-c) fabrication of MXene-Sponge/PVA NWs based sensor[64]