The Effect of Geometry on Sample Leakage in Multi-Channel Microfluidic Devices

Abstract

Electrokinetic sheath-flow is one of the techniques used to manipulate sample migration and prevent cross-contamination in multi-channel microfluidic devices. To achieve a successful design, it is important to predict the sample behaviour in advance. We use finite element method to investigate the effect of channel geometry on sample leakage in the presence of electrokinetic sheath-flow. A typical multi-channel device consisting of a main fractionation channel connected to a few collection channels is considered. It has been observed experimentally that the depth of different components of the microfluidic device can change the sample leakage. In-detail investigations are made here in order to find the fundamental cause of the observed behaviour. Simulation results confirmed that by increasing the depth ratio of the collection channels to the main channel the sample leakage would decrease. Simulations are also performed to find criteria for choosing an optimum depth ratio for the channels in terms of both high functionality and ease of fabrication for any specific application.