A bio-inspired microfluidic concentrator for regenerated silk fibroin solution

In this article, microfluidic channels (500 μm in width, 65–85 μm in depth) in micro-chips were fabricated in poly-(dimethylsiloxane) (PDMS) on a mold of SU-8 photoresist based on photolithography process. By biomimicking the silk glands and the spinning duct of silkworms, the chips were designed and used for the concentration of regenerated silk fibroin (RSF) aqueous solution. The microfluidic devices based on regenerated cellulose membrane involve a flow of RSF aqueous solution on a donor side and a flow of polyethyleneglycol (PEG) aqueous solution on an acceptor side. The enrichment factor was characterized by varying the flow rates of the RSF solution and the PEG solution, and the concentrations of PEG and RSF solutions at inlets. The results showed that the enrichment efficiency varied as the flow factors changed. The RSF concentration of the solution was enriched up to 31.2 wt% from 12 wt% by using the microfluidic chip. The experiments facilitated the enrichment of RSF solution in a microfluidic channel as silkworm did. It might be further applied for the microfluidic spinning of RSF fiber.