(324c) A Novel Electrokinetic-Electromechanical Microfluidic Platform Using Conductive Carbon Black Membranes

Conductive materials have been widely utilized and integrated into microfluidic devices for on-chip electrokinetic applications. While the high electrical conductivity of metal films such as gold, chrome and indium tin oxide (ITO) makes them suitable for delivering electric field to fluid contained within these microfluidic chips, these structures are expensive to fabricate and are typically confined to the microfluidic channel surface, which limits their ability to electrokinetically manipulate the flow volume. On the contrary, soft materials like agarose gel and hydrogels are cheaper and easier to fabricate into 3D structures. Their poor mechanical strength, however, often leads to unreliable devices with unstable electrokinetic performance. In this talk we present a new 3D microfluidic platform based on conductive carbon black nano-composite PDMS. By locally patterning conductive PDMS directly into the sidewalls of a microfluidic flow channel, we demonstrate the ability of this platform to perform a wide variety of on-chip electrokinetic applications including electro-osmosis, free-flow electrophoresis and isotachophoresis. These electrokinetic actuators can also serve as mechanical sensors. Because the patches are both conductive and flexible, there is a two-way conductivity-force interaction between the channel sidewall and the fluid pressure. Using this electro-mechanical feature, we also show how devices capable of performing on-chip electrophoresis and electro-osmosis can be used to measure the pressure gradient and flow rate within the same channel. Therefore, this conductive side-wall platform offers a useful means of performing electrokinetic actuation and electro-mechanical detection using the same design.