Lithographic printing inspired in-situ transfer of MXene-based films with localized topo-electro tunability for high-performance flexible pressure sensors

MXene-based films have been intensively explored for construction of piezoresistive flexible pressure sensors owing to their excellent mechanical and electrical properties. High pressure sensitivity relies on pre-molding a flexible substrate, or regulating the micromorphology of MXene sheets, to obtain a micro-structured surface. However, the two avenues usually require complicated and time-consuming microfabrication or wet chemical processing, and are limited to non-adjustable topographic-electrical (topo-electro) properties. Herein, we propose a lithographic printing inspired in-situ transfer (LIPIT) strategy to fabricate MXene-ink films (MIFs). In LIPIT, MIFs not only inherit ridge-and-valley microstructure from paper substrate, but also achieve localized topo-electro tunability by programming ink-writing patterns and cycles. The MIF-based flexible pressure sensor with periodical topo-electro gradient exhibits remarkably boosted sensitivity in a wide sensing range (low detection limit of 0.29 Pa and working range of 100 kPa). The MIF sensor demonstrates versatile applicability in both subtle and vigorous pressure-sensing fields, ranging from pulse wave extraction and machine learning-assisted surface texture recognition to piano-training glove (PT-glove) for piano learning. The LIPIT is quick, low-cost, and compatible with free ink/substrate combinations, which promises a versatile toolbox for designing functional MXene films with tailored morphological-mechanical-electrical properties for extended application scenarios.