Dean number effects on the mixing quality of low aspect ratio microfluidic devices

Flow manipulation in microfluidic devices is critical for their various applications in fields such as lab-on-a-chip, biological research, and medical diagnostics. Recent research found that curved channels with varying aspect ratios shifted the distribution of Dean vortices that form in the vertical plane due to a combination of inertial, centrifugal, and viscous effects. We investigated the effect of low Dean flows (De < 20) on low aspect ratio curved channels of microfluidic devices with bumps on the channel walls. We show that for ideal mixing performance, the position and number of bumps on the microfluidic devices needed to be optimized. We also found that mixing may occur at surprisingly low De and low aspect ratios (<1/5).