Au/PPy Actuators for Active Micromixing and Mass Transport Enhancement

This study documents our efforts towards a novel design of an active micromixing device that employs Gold/Polypyrrole (Au/PPy) actuators. The devices were manufactured by the sequential deposition of a polyimide layer, a thermal evaporation of gold, and electrodeposition of PPy layer on top of the gold electrodes. Several types of mixers ranging in size from 10 by 1 mm to 380 by 38 μm were successfully actuated at frequencies up to 3 Hz. Mass transport in the solution was studied in a series of chronoamperometric experiments with a Redox sensor placed in close proximity to the actuators. Differential mass transport effects with and without the actuation of micromixers were recorded for several system configurations. In addition, numerical simulations of a biological surface-microreaction (i.e., DNA hybridization) were carried out. Simulation results indicate that compared to passive diffusion-limited transport active micromixing is capable of increasing reaction rates by 30% for sub-mm size actuators and by 100% for mm-size actuators.