Design and development of an efficient fluid mixing for 3D printed lab-on-a-chip

In this paper, we present elaborate study of design parameters of hybrid microfluidic mixer through numerical approach using finite element method and experimental studies to improve mixing efficiency in 3D printed lab on a chip. We investigated the change in mixing efficiency by varying passive parameters like intersection angle of the channel inlet V-leg, barrier shape, barrier orientation and the contours of the wall surface as well as the active parameters such as electric field, frequency and number of electrodes to change the electroosmotic flow-induced mixing behavior inside the mixing zone. The optimum design is then experimentally verified by using a 3D additive manufacturing printing technique to fabricate the mixing device. Analysis of Reynolds number versus mixing index indicates the efficiency to be better at lower flow rate while using electroosmotic mixing as well. The study of non-dimensional Peclet number reveals that four electrodes per side on the channel wall yield the maximum mixing within the operating range of this device. Putting it all together, the mixing efficiency reaches close to 50% when the barriers are staggered, waviness is absent in wall surface, intersection angle of the two inlets V-leg is close to 50 degrees and the inlet flow rate is low. The optimal hybrid mixer design and implementation presented in this paper can enable further development of next generation 3D printed lab-on-chip devices.