Rational shaping of hydrogel by electrodeposition under fluid mechanics for electrochemical writing on complex shaped surfaces at microscale

• “Electrodeposition + Pulling” is proposed for processing and shaping hydrogel. The process synergistically combines electrochemistry with fluid mechanics. Rational control relies on electrodeposition kinetics meniscus evolution. Sharp hydrogel probes of width < 1 µm are obtained local electrochemistry. Electrochemical writing complex 3D structures achieved at tunable resolution. precise high resolution an intrinsic engineering challenge due to the low solid content material. Most approaches based lithographic mold, which becomes tricky demold when precision rises micron sub-micron range. In this work, a novel automated “electrodeposition pulling” approach rationally chitosan in reported. Taking advantage transient generated while pulling sharpened metal wire out from viscous solution, confines simultaneously it. Considering that driven by electrochemically OH ? ions, reaction mass transport gelification mechanics dynamic process. With automation mastering process, shape can be tuned, it below tip desired length. Thus, demonstrated electrochemical printed shaped surfaces. soft contact sample, allowing deposition or etching reactions spatially localized area. By precisely pressing stretching hydrogel, tuned few tens microns just like traditional ink brushes, may significantly improve efficiency writing. work shows power towards spatial micro nano scale.