Two-photon printing of monolithic glass electrospray emitters with TPMS micro-architectures

Abstract The performance of electrospray thrusters is limited by the precision and constraints of traditional emitter fabrication techniques, which often lack resolution, geometric flexibility, or material compatibility for optimal emitter design and fabrication. Here, we demonstrate a high-resolution additive manufacturing approach for fabricating monolithic fused-silica electrospray emitters using two-photon polymerization (TPP) printing followed by thermal conversion. Triply-periodic-minimal-surface (TPMS) microporous structures were embedded within the emitter body to provide passive capillary transport of propellant to the emitter tip. Optical profilometry and electron microscopy confirm high geometric fidelity to the target design and uniform shrinkage of approximately 40% during thermal processing, with preservation of the TPMS architecture. Electrospray emission testing was performed with ionic liquid EMI-BF4 propellant, which showed stable and repeatable emission with onset voltages of 2.4 - 2.6 kV, linear current-voltage characteristics, and high single emitter thrust of 64 nN at specific impulse values exceeding 3000 s. These results establish TPP-printed fused-silica emitters with integrated TPMS architectures as a robust and versatile platform for scalable electrospray propulsion systems.