Types of Microfluidic Channels and Working Principles

Microfluidic channels can be classified according to geometry and function.

1. Straight channels

A simple rectangular or circular passage transports fluid from inlet to outlet. At low Reynolds number, flow is mainly laminar and pressure-driven.

2. Serpentine channels

The channel contains repeated bends. The longer path increases residence time and can enhance mixing through repeated deformation of fluid streams.

3. T-junction channels

Two streams meet at a T-shaped junction. They are commonly used for controlled mixing and droplet generation.

4. Y-junction channels

Two inlet streams merge at an angle into one channel. They are useful for controlled co-flow and diffusion-based mixing.

5. Flow-focusing channels

A central stream is squeezed by side streams, allowing controlled formation of droplets or particles.

6. Microchambers

Expanded regions connected to channels provide space for reactions, cell trapping, sensing or incubation.

Working principle

Fluid movement is produced by pressure-driven flow, electroosmotic flow or other microscale actuation methods. Because flow is generally laminar, mixing is often achieved by diffusion or deliberate channel geometry rather than turbulence.