Capillary liquid bridge soft lithography for micro-patterning preparation based on SU-8 photoresist templates with special wettability

Abstract

Patterned micro-nano arrays have shown great potential in the fields of optics, electronics and optoelectronics. In this study, a strategy of interface-induced dewetting assembly based on capillary liquid bridges and SU-8 photoresist templates is proposed for patterning organic molecules and nanoparticles. First, photoresist templates with chemical stability were prepared via a simplified lithography method. Then the interface wettability and the contact angle hysteresis of water droplets on the fluorosilane modified templates were adequately studied and discussed. Subsequently, a sandwich structure, composed of a superhydrophilic target substrate, a hydrophobic high adhesive photoresist template and a growth solution were introduced for the confined space dewetting assembly. The related mechanism was investigated and revealed, with the assistance of in situ observation via a fluorescence microscope. Finally, the patterned arrays of water-soluble organic small molecules and aqueous dispersed nanoparticles were successfully obtained on the target substrates. This method is simple and easy, and the SU-8 photoresist templates possess a series of advantages such as low processing cost, short preparation periods and reusable performance, which endow this strategy with potential for application in molecular functional devices.