A new low-cost fabrication method of SU-8 micro–nano channels and needle tip in electro-hydrodynamic jet chips

Abstract

Electro-hydrodynamic (EHD) jets are widely used for direct writing of micro and nano structures. However, the application of an EHD jet is limited by its high-cost production process. To overcome the drawbacks mentioned above, a new fabrication method of polymer EHD jet needle is proposed in this paper. A silicon nano mold is firstly produced by inclined deposition technique, and a micro–nano PDMS mold is developed by casting double-layer PDMS on the silicon nano mold with a photomask film between the two PDMS layers. Using the micro–nano PDMS mold, a micro–nano needle can be fabricated in SU-8 photoresist layers by thermal nanoimprinting and ultraviolet lithography. In the manufacturing process, the exposure parameters and the thermal bonding parameters were optimized. The final chip consists of micro–nano channels, in which the nano channels are 380 nm in width and 72 nm in depth. The chip is tested with fluorescent dye, indicating that the micro–nano channels are fabricated without blockage or leakage. This low-cost fabrication method of micro–nano needle may have a great contribution to direct write-on-demand nano-patterning technology.