Patterned mask etching enhanced electrohydrodynamic printing for terahertz metasurfaces

Electrohydrodynamic (EHD) printing offers a unique synergy of high resolution, flexible substrate compatibility, and environmentally friendly and cost-effective process, making it ideal for next-generation terahertz (THz) metasurfaces, especially those that are conformal, customized, or integrated into flexible systems. For example, in applications such as wearable THz sensors, curvy cloaks, or on-demand functional prototypes, EHD printing outperforms conventional methods such as photolithography, laser writing, and nanoimprint lithography in terms of adaptability and integration flexibility. However, current maskless EHD printing is hindered by several challenges, including insufficient conductivity that weakens resonance strength, suboptimal edge definition that compromises the fidelity of meta-atom features, and low throughput that restricts large-area scalability. Here, we introduce a mask etching process (MEP) integrated with EHD printing to address these limitations, enabling the fabrication of large-area, high-resolution (<10 μm) THz metasurfaces. The conductivity is improved sixfold, achieving 3.33 × 107 S/m, which is remarkably close to the bulk conductivity of gold (4.52 × 107 S/m). Both simulations and experimental results substantiate that the fabricated THz metasurfaces exhibit exceptional electromagnetic characteristics, including efficient absorption and filtering. This MEP-enhanced EHD printing strategy thus provides a versatile, scalable, and cost-effective approach for high-resolution THz metasurface fabrication. Moreover, it can be readily extended to other similar devices requiring high-resolution patterning and large-area array integration.