Microfluidic bead-based diodes with targeted circular microchannels for low Reynolds number applications

Area of Science:

• Microfluidics
• Biotechnology
• Nanotechnology

Background:

• Self-regulating fluidic components are vital for microfluidic processors in diagnostics and drug delivery.
• Existing microfluidic diodes struggle with low Reynolds number (Re) flows and micro/nanoscale platforms.
• Previous microbead-based diodes using spherical particles in rectangular channels have limitations.

Purpose of the Study:

• To develop a microfluidic diode capable of rectifying low Re flows using a single microbead.
• To optimize the diode's performance by precisely matching the microbead and docking channel geometry.
• To investigate the effect of series and parallel arrangements of these diodes on overall device performance.

Main Methods:

• Designed and fabricated a single-layer microfluidic diode (18 μm height) with a targeted circular docking channel (15 μm diameter) for a single microbead.
• Utilized 3D simulations and experimental validation to analyze fluid flow rectification.
• Tested arrays of diodes in series and parallel configurations.

Main Results:

• The optimized bead-based diode demonstrated effective flow rectification at low Re.
• Adjusting docking channel geometry to match the microbead significantly improved diodicity (Di).
• Series arrangement of four diodes enhanced performance, achieving average Di's from 2.72 ± 0.41 to 10.21 ± 1.53 for Re 0.1–0.6.

Conclusions:

• A novel microfluidic diode utilizing a single, precisely docked microbead effectively rectifies low Re flows.
• The design overcomes limitations of previous microbead diode approaches.
• Series arraying of these diodes offers a scalable strategy for enhanced microfluidic flow control.