Manipulation and flow of biological fluids in straight channels micromachined in silicon

Analysis of minute sample volumes is a major analytical challenge that requires an understanding of fluid flow in microstructures. Accordingly, flow dynamics of biological fluids and cell suspensions in straight glass-capped silicon microchannels (40 to 150 microns wide, 20 and 40 microns deep) were studied. We demonstrated that these microstructures are appropriate components for microfluidic analytical devices. Different fluids were easily manipulated in the microchannels, and measurements of flow rate as a function of pressure for whole human blood, serum, plasma, and cell suspensions revealed non-Newtonian behavior. By means of micromachined filters (5 microns) located in channels, blood cells and microparticles were effectively separated from nanoliter-sized samples, clearly indicating the future role of microstructures for a variety of analytical purposes.