Abstract
We have developed a cast microfluidic chip that contains a thin (〜0.5 μm wide) microchannel that is smoothly connected to thick microfluidics. The thin line features having high aspect ratio for a low-cost photolithography in which an emulsion photomask was used (1:1〜1:3) were fabricated by exposing SU-8 photoresist to diffused 185 nm UV light emitted by a low-cost ozone lamp from the backside of the substrate to ensure sufficient crosslinking of small regions of the SU-8 photoresist. An T-shaped microfluidic configuration was used, in which the thin channel maintained constant diffusion fronts beyond purely static diffusion. T-head-formed microfluid constitution was used, in which we performed the evaluation that the thin waterway could maintain the constant concentration gradient across the totally static spread. By using this device, we can generate the concentration gradient, and maintain the concentration gradient for 6days. This result was caused by hydrostatic pressure at reservoir. We may be able to control the concentration gradient condition by controlling hydrostatic pressure.
