Drag Reduction Effect of BSA Monodispersed Solution in Microtube Flow

In recent biological and chemical analyses, microchips have attracted attention because of advantages such as high efficiency, small heat capacity, and high-speed reaction. Biochemical reagents and samples flow into the chips with the wall surface biologically or chemically modified. The mechanisms of the complex flow are not well-known. In this paper, the mechanisms are investigated using pressure drop measurements of the flow of BSA-(bovine serum albumin, protein generally used in analytical fields) dispersed solutions in microtubes with three kinds of surfaces: glass, PEEK (polyetheretherketone) and Hirec-X1 (a highly water-repellent agent, NTT-AT Co.), which have different properties. In the cases in which BSA solution flows on the Hirec-X1 and on the PEEK surface, results show reductions in the friction factor. On the other hand, in the case in which non BSA solution flow on any surface, results agree well with the Hagen-Poiseuille equation. Furthermore, reduction ratio in the friction factor depends on the concentration of BSA. These results imply that the interaction between the wall and the bio-molecules influences the behavior of the flow in microtubes.