Putting motile bacteria to work

Bacteria swim by exploiting the frictional drag forces encountered in their low Reynolds number environment. This is a world in which viscous forces overwhelm inertial forces. Designers of microscale hydrodynamic devices work in a similar realm. So we ask whether motile bacteria can be employed to solve some of the problems encountered in microfluidic devices. When deposited on a surface at a fluid interface, might they produce useful flows? When deposited on the surface of a polystyrene bead, might they move that bead around? We show movies of fluorescent motile bacteria and the movement of their flagella. We describe a robust and simple technique for attaching Serratia marcescens to polydimethylsiloxane (used in soft micro-fluidic devices) and to polystyrene beads (as sample objects for bacterial transport). Finally, we present evidence demonstrating enhanced flow and motion.