COMSOL-Based Design and Validation of Dilution Algorithm with Continuous-Flow Lab-on-Chip

Abstract

Sample preparation is an essential component in any biochemical analysis, which involves, among others, the task of producing dilutions of raw sample, and fluid-mixtures of different reagents with prescribed proportions. In this work, a dilution method using continuous-flow microfluidic (CFM) lab-on-chip (LoC) is proposed, and a universal fluidic network for its implementation is designed. The mixing of fluids is effected by the convective/diffusive transport through specially designed Y-shaped serpentine microchannels. Our method does not need any valve-control, and instead of emitting waste droplets at each mix-split step as practiced earlier in the case of digital microfluidics, we adjust fluid-injection velocities or the dimension of inlet tubes as needed. The target concentration factor of the fluid computed via COMSOL simulation of the network matches favorably with the expected value. Furthermore, this investigation provides an effective procedure towards the design of CFM biochips needed for automated sample preparation with any given input ratio.