The Design and Control of Catalytic Motors: Manipulating Colloids and Fluids with Self-Generated Forces

ABSTRACTMicrofabrication was employed to pattern silver (Ag) on a gold (Au) surface. The two metals served as bimetallic heterogeneous catalysts for the heterogeneous decomposition of H2O2. Silver was the cathode, carrying out H2O2 reduction (to water) and gold the anode carrying out H2O2 oxidation (to oxygen). Both protons and electrons are created at the anode (as a part of the reaction) and migrate to the cathode (migration of ions is a current) where they are consumed. Thereby establishing an electric field (migration of ions obeys Ohm's law), which passively pumps fluids through electroosmosis. Electrophoresis also present as either an additive component to the electroosmotic flow or results in pattern formation (occurs at point where electroosmosis is equal and opposite to that of electrophoresis). Herein, the electrokinetic model is further tested and validated as chemical methods to tune the tracer behavior (convection to pattern formation), design of asymmetric patterns through microfabrication and attempts to indirectly measure the electric field were successful.