SU-8 microfluidic mixer for use in lab-on-a-chip devices for biological fluids analyses

This paper describes an easy-to-fabricate and low-cost SU-8 microfluidic mixer suitable for enabling a mixing process based on diffusion. It is developed to be an integrated part of a lab-on-a-chip for measuring the concentration of four biomolecules in urine samples, by optical absorption. The design of the microfluidic system is based on computational fluid dynamics techniques. Mixing and reaction of the components of the process must be simulated by solving the flow and mass transport equation. A good design must guarantee the mixing of the reactants to assure an uniform mixture at the detection zone. The resulting design and the experimental results are supported by numerical simulations, which allow a reliable quantitative analysis of the concentrations after the mixing process. The reduced size, weight and the simultaneous measurement of more than one biomolecule concentration will improve the performance of biological fluids analyses in clinical laboratories and consequently the quality of the medical diagnostic.