Kirigami-Inspired Highly Stretchable, Conductive, and Hierarchical Ti₃C₂T_<i>x</i> MXene Films for Efficient Electromagnetic Interference Shielding and Pressure Sensing.

Abstract

Although Ti₃C₂T_<i>x</i> MXene sheets are highly conductive, it is still a challenge to design highly stretchable MXene electrodes for flexible electronic devices. Inspired by the high stretchability of kirigami patterns, we demonstrate a bottom-up methodology to design highly stretchable and conductive polydimethylsiloxane (PDMS)/Ti₃C₂T_<i>x</i> MXene films for electromagnetic interference (EMI) shielding and pressure sensing applications by constructing wrinkled MXene patterns on a flexible PDMS substrate to create a hierarchical surface with primary and secondary surface wrinkles. The self-controlled microcracks created in the valley domains of the hierarchical film <i>via</i> a nonuniform deformation during prestretching/releasing cycles endow the hierarchical PDMS/MXene film with a high stretchability (100%), strain-invariant conductivity in a strain range of 0%-100%, and stable conductivities over an 1000-cycle fatigue measurement. The stretchable film exhibits a highly stable EMI shielding performance of ≈30 dB at a tensile strain of 50%, and its EMI shielding efficiency increases further to 103 dB by constructing a two-film structure. Furthermore, a highly stretchable and sensitive iontronic sensor array with integrated MXene-based electrodes and circuits is fabricated by a stencil printing process, exhibiting high sensitivity (66.3 nF kPa^-1), excellent dynamic cycle stability over 1000 cycles under different frequencies, and sensitive pressure monitoring capability under a tensile strain of 50%.