A highly flexible and sensitive piezoresistive sensor based on MXene with greatly changed interlayer distances

TLDR

MXenes are versatile two‑dimensional materials used in energy storage, EMI shielding, transparent electrodes, and transistors, yet their pressure‑induced interlayer distance changes have not been harnessed in practical devices. The authors develop a highly flexible, sensitive piezoresistive sensor that exploits this interlayer distance modulation. In situ transmission electron microscopy demonstrates that external pressure dramatically alters MXene interlayer spacing, providing the fundamental operating principle of the sensor. The device exhibits a gauge factor of ~180.1, a response time below 30 ms, and highly reversible compression, allowing it to detect subtle human bending and weak pressures.

Abstract

Since the successful synthesis of the first MXenes, application developments of this new family of two-dimensional materials on energy storage, electromagnetic interference shielding, transparent conductive electrodes and field-effect transistors, and other applications have been widely reported. However, no one has found or used the basic characteristics of greatly changed interlayer distances of MXene under an external pressure for a real application. Here we report a highly flexible and sensitive piezoresistive sensor based on this essential characteristics. An in situ transmission electron microscopy study directly illustrates the characteristics of greatly changed interlayer distances under an external pressure, supplying the basic working mechanism for the piezoresistive sensor. The resultant device also shows high sensitivity (Gauge Factor ~ 180.1), fast response (<30 ms) and extraordinarily reversible compressibility. The MXene-based piezoresistive sensor can detect human being's subtle bending-release activities and other weak pressure.