Ultra-Stretchable\nMicrofluidic Devices for Optimizing\nParticle Manipulation in Viscoelastic Fluids

Viscoelastic microfluidics leverages the unique properties\nof non-Newtonian\nfluids to manipulate and separate micro- or submicron particles. Channel\ngeometry and dimension are crucial for device performance. Traditional\nrigid microfluidic devices require numerous iterations of fabrication\nand testing to optimize these parameters, which is time-consuming\nand costly. In this work, we developed a flexible microfluidic device\nusing ultra-stretchable and biocompatible Flexdym material to overcome\nthis issue. Our device allows for simultaneous modification of channel\ndimensions by external stretching. We fabricated a stretchable device\nwith an initial square microchannel (30 μm × 30 μm),\nand the channel aspect ratio can be adjusted from 1 to 5 by external\nstretching. Next, the effects of aspect ratio, particle size, flow\nrate, and poly(ethylene oxide) (PEO) concentration that make the fluid\nviscoelastic on particle migration were investigated. Finally, we\ndemonstrated the feasibility of our approach by testing channels with\nan aspect ratio of 3 for the separation of both particles and cells.