Balancing of Flow at Microfluidic Apertures

Computational fluid dynamics simulations are used to obtain a radially symmetrical flow profile at an aperture of a microfluidic channel by manually arranging flow‐directing obstacles around the aperture. For the first time, the flow profile is improved by calculating the coefficient of variation (CoV), which is applied to the flow velocity magnitude along coaxially arranged circles below the aperture in the microfluidic channel. A minimum CoV of 0.03 is obtained at the circle with the same diameter as the aperture. Channels with the optimized design are fabricated by lamination of two layers of dry film resist and patterned with UV‐lithography. The aperture is formed by using an inductively coupled plasma reactive ion etching process. Video recording of the flow behavior confirmed the simulation results experimentally. The proposed channel design and the optimization method can favorably be used for a balanced hydrodynamic trapping of particles or cells at apertures.