Fluidic‐Enabled Formation of EGaIn Capsules and Droplets With Tunable Surface Chemistry and Electromechanics

ABSTRACT The combination of high electrical conductivity and fluidity and biocompatibility exists in liquid metals including eutectic gallium–indium (EGaIn) but their application remains restricted because of spontaneous oxide development and unstable flow behavior. Here we describe a microfluidic method to create EGaIn droplets and capsules with adjustable dimensions and mechanical and surface properties. The acidity level of the suspending fluid, ethanol, determines whether EGaIn will create oxide‐covered capsules or non‐oxidized liquid droplets. The oxide coating stabilizes spherical shapes, which deform irreversibly. Droplets readily reform into spheres after applied stress is removed, but are susceptible to coalescence. A thiolated PEG–click complex forms self‐assembling structures at metal–liquid interfaces to protect droplets from merging while allowing surface modification. When cast in thin films, the fluidic‐generated EGaIn structures exhibit different electromechanical responses: oxide‐coated capsules function as field‐effect elements while thiol‐stabilized droplets operate as ohmic conductors. By integrating microfluidic generation, shape programmability, and chemical stabilization, we open new pathways to multifunctional liquid–metal architectures with controllable electromechanical response.