Electroosmotic flow in microchannel with black silicon nanostructures

Abstract

Electroosmotic flow (EOF) is an electrokinetic phenomenon. The fluid motion originates from the electrical body force acting on the excess counterions in the electrical double layer (EDL) when an external electric field is applied across a microchannel. It can be employed in numerous microfluidic applications, ranging from pumping to chemical and biomedical analyses. Nanoscale networks/structures are often integrated within microchannels for a broad range of applications, such as sieving matrices for electrophoretic separation of biomolecules, and its introduction has been known to reduce EOF [1, 2]. Hitherto, the mechanics for EOF reduction due to nanostructured surfaces is still not well understood. To better elucidate the mechanics, we develop a novel fabrication method to produce microchannel with large-area nanostructures for investigation. The micro-/nanostructures produced demonstrate good regularity over a relatively large area and can be mass-produced cost-effectively. Despite the availability of various micro-/nanofabrication techniques, the existing techniques do not satisfy the aforementioned criteria.