A high-efficiency oil-to-water micro-channel mixer/extractor by surface modification with patterned multiple SAMs for flow-guide

A micro-channel passive mixer and oil-to-water extractor is proposed, where oleophobic/oleophilic `two-tone' stripes are modified at surface by patterning multiple SAMs (self-assembled monolayers) with UV-light exposure through hollowed hard-mask. With the novel technique the grown oleophobic SAM of FAS-17 can be region-selectively removed and the oleophilic SAM of OTS can be re-grown there. This process-cycle can be repeated for patterning multiple SAMs at wafer-level. Oil chaotic-flow can be generated on the `two-tone' stripes. The interface area of oil/water is enlarged and transverse flow is generated, and thus, high-efficiency oil-to-water mixing/extraction are achieved with the surface-directed 3D spiral flow.