Dry-Transferable Photoresist Enabled Reliable Conformal Patterning for Ultrathin Flexible Electronics.

Photolithographic techniques, which are widely used in the silicon-based semiconductor industry, enable the manufacture of high-yield and high-resolution features at the micrometer and nanometer scales. However, conventional photolithographic processes cannot accommodate the micro/nanofabrication of flexible and stretchable electronics. In this study, a microfabrication approach that uses a synthesized, environmentally friendly, and dry-transferable photoresist to enable the reliable conformal manufacturing of thin-film electronics is reported, which is also compatible with the existing cleanroom processes. Photoresists with high-resolution, high-density, and multiscale patterns can be transferred onto various substrates in a defect-free and conformal-contact manner, thus enabling multiple wafer reuses. Theoretical studies are conducted to investigate the damage-free peel-off mechanism of the proposed approach. The in situ fabrication of various electrical components, including ultralight and ultrathin biopotential electrodes, has been demonstrated, which offer lower interfacial impedance, durability, and stability, and the components are applied to collect electromyography signals with superior signal-to-noise ratio (SNR) and quality. Additionally, an exemplary demonstration of a human-machine interface indicates the potential of these electrodes in many emerging applications, including healthcare, sensing, and artificial intelligence.