Selective Deposition of Charged Droplets for Programmable and Rewritable Printing of Patterned Microstructure Arrays.

Patterned microstructure arrays are widely used in flexible electronics, optics, and biosensing, yet fabrication still relies on costly, process-intensive methods (e.g., photolithography) with limited reconfigurability. In this work, we introduce a method for the selective deposition of charged droplets via residual-charge-induced electric field control (SDREC), enabling microstructure-array patterning with a resolution of 20 µm through the controlled assembly of charged microdroplets on silk fibroin surfaces. As a proof of concept, a programmable 5×5 pixel array was fabricated, demonstrating reversibility through erasure and rewriting. By transferring the patterned microstructures onto a shape memory polymer, we further achieved information storage and optical encryption/decryption. In addition, pre-deposition of silver nanoparticles within the patterned areas enabled the fabrication of silver electrodes. Overall, the SDREC strategy offers advantages such as high resolution, structural reconfigurability, and multifunctionality, providing a promising approach for the rapid construction of high-precision microstructured devices.