Electroosmotic Flow in Microchannel with Black Silicon Nanostructures

Area of Science:

• Microfluidics
• Surface Science
• Nanotechnology

Background:

• Electroosmotic flow (EOF) is crucial for microfluidic devices but can negatively impact applications like electrophoresis.
• Existing methods to suppress EOF, such as polymer coatings or nanostructures, have limitations.

Purpose of the Study:

• To present a novel technique for fabricating microchannels with black silicon nanostructures for EOF suppression.
• To experimentally and numerically investigate the effect of these nanostructures on EOF velocity.

Main Methods:

• Fabrication of microchannels with black silicon nanostructures using Dry Etching, Electroplating and Molding (DEEMO) and reactive ion etching (RIE).
• Experimental examination of EOF reduction using the current monitoring method.
• Numerical analysis using finite element simulations to model EOF behavior.

Main Results:

• Experimental results showed a reduction in EOF velocity by 13 ± 7%.
• Numerical simulations predicted an approximate 8% reduction in EOF velocity.
• Simulations indicated that EOF velocity decreases with increasing nanostructure height or decreasing diameter.

Conclusions:

• Black silicon nanostructures effectively suppress EOF in microfluidic channels.
• The DEEMO process offers a tunable method for creating nanostructures for precise EOF control.
• This research provides fundamental insights into EOF behavior on nanostructured surfaces, with applications in chemical and biological analyses.