Cryo-ultramicrotomy fabrication of ultra-thin conductive PEDOT:PSS hydrogel films

Abstract The fabrication of defect-free, nanometrically thin conductive hydrogel films is a critical yet challenging step in advancing flexible bioelectronics. Conventional techniques often result in microstructural heterogeneity and limited resolution, particularly for thicknesses below 50 nm. Here, we report a novel manufacturing strategy based on cryo-ultramicrotomy for producing ultra-thin, structurally pristine films of PEDOT:PSS hydrogel. This method involves the vitrification of the bulk hydrogel in liquid nitrogen, followed by precise nanocutting at cryogenic temperatures (-160 °C) using a diamond tool. This process successfully preserves the material's intrinsic porous nanostructure while enabling the production of continuous films. Structural characterization confirmed a highly uniform thickness of approximately 50 nm and the intact nanoscale network. Electrically, the films exhibited excellent ohmic behavior and high conductivity, with resistance values as low as ~85 Ω, demonstrating an efficient percolation pathway. Our work establishes cryo-ultramicrotomy as a powerful and reproducible technique for the extreme nanofabrication of soft electronic materials, opening new avenues for high-performance, rapid-response devices such as electronic skin and bio-integrated systems.