Needle‐free, Liquid Metal‐embedded Electrospray Deposition System for Controlled Microdroplet Printing

Electrospray systems have been widely utilized in biomedical, pharmaceutical, and materials science applications due to their ability to enable precise liquid manipulation and efficient ionization. However, conventional electrospray technologies often rely on external ionization components and involve complex system designs, leading to challenges such as clogging, reduced efficiency, and limited reproducibility. This study presents a liquid metal-embedded electrospray deposition (LM-ESD) system that incorporates liquid metal within a microfluidic electrospray setup, eliminating the need for additional ionization hardware. By leveraging the intrinsic electric field of the microfluidic chip, the LM-ESD system simplifies the fabrication process, reduces design complexity, and enhances overall system efficiency. The spray performance is validated using fluorescence microscopy, scanning electron microscopy, atomic force microscopy, Kelvin probe force microscopy, and Raman spectroscopy, all of which confirm the formation of uniform droplet arrays with high reproducibility. This versatile LM-ESD system shows strong potential for applications in precision printing, thin-film deposition, and array-based high-throughput analysis.