Ti3C2Tx MXene-graphene composite films for wearable strain sensors featured with high sensitivity and large range of linear response

Strain sensors featured with high sensitivities and large ranges of linear responses are currently under urgent needs. Herein, we present a spontaneously formed Ti3C2Tx/graphene/PDMS layered structure, which can be divided into two layers when being stretched: a Ti3C2Tx dominated brittle upper layer and a flexible graphene/PDMS composite bottom layer. The balance between the destruction and maintenance of the conductive pathways through the synergetic motion of the upper and bottom layers ensure a high and steady gauge factor of the senor in a wide strain range (e.g., gauge factors of 190.8 and 1148.2 in strain ranges of 0–52.6% and 52.6–74.1%, respectively). The Ti3C2Tx/graphene/PDMS layered structure based strain sensor is also featured with a low detection limit (~0.025%), a high linearity (R2 > 0.98), a high cycling stability (over 5000 cycles), and an accurate monitoring of full-range human motions. Different breathing patterns in yoga are distinguished to demonstrate the practicability of the sensor.