All-Solid-State, Maskless Electrodeposition of Ag Microstructures Using a Polymer Electrolyte Membrane Stamp.

Ag micro- and nanostructured surfaces play an important role in optoelectronic devices and bio/chemical sensing, particularly in applications that require mechanical flexibility. Conventional patterning methods rely on top-down processes that involve complex lithographic steps, resulting in high material consumption and environmental burden. Bottom-up approaches enable the direct formation of metallic patterns but are limited by insufficient patterning resolution. Herein, we report an all-solid-state electrodeposition process employing a polymer electrolyte membrane (PEM) stamp for the direct fabrication of multiscale Ag patterns on flexible substrates. Ag ions supplied by anodic dissolution at the Ag anode/PEM interface are transported through nanoscale water channels in the PEM, enabling electrodeposition without liquid electrolytes. Electrochemical measurements clarified the interfacial reactions between the PEM and the electrodes. Electron and X-ray analyses confirmed the formation of metallic Ag films at the cathode-PEM interface. Ambient humidity governs pattern formation: low-humidity conditions yield positive patterns via contact-region deposition, whereas high-humidity conditions produce negative patterns through water-assisted Ag+ transport in noncontact regions. Under optimized conditions, Ag patterns with feature sizes ranging from several hundred nanometers to the submillimeter scale were achieved. The deposited Ag films exhibited electrical conductivity, mechanical stability, and enhanced Raman signals, demonstrating their proof-of-concept utility as flexible conductive structures and plasmonic sensing substrates.