Flowrate independent 3D printed microfluidic concentration gradient generator

Abstract

Christmas tree like microfluidic concentration gradient generators (MCGG) and other geometries as well, rely on molecular diffusion to achieve concentration gradients. This condition limits the flowrate in the case of continuous flow gradient generators in order for complete mixing to be achieved in a branch before reaching the next bifurcation. Therefore these MCGG work well at low Peclet numbers (Pe). In this work, a different concept of MCGG is presented where accurate and arbitrary dosing can be achieved prior to mixing, making this simple microfluidic design flowrate independent. This means that arbitrary concentration profiles can be achieved, at any flowrate in the laminar flow regime. In order to show the performance of this MCGG, both experiments and numerical simulations were performed. The results were compared to a classical Christmas tree MCGG. The experimental microfluidic chips were 3D printed with a commercial low cost LCD resin printer and commercial grade water cleaning clear resin.