Microfluidic Channel Dimension Calculator
Design microfluidic chip channels by calculating dimensions from target shear stress or determining shear stress from known geometry. Optimize on-chip flow conditions with hydraulic and fluid dynamics analysis.
Parameters
Result
| Parameter | Value |
|---|---|
| Width | 54.32 µm |
| Height | 13.58 µm |
| Aspect Ratio | 4.00:1 |
| Wall Shear Stress | 10.00 Pa |
| Hydraulic Diameter | 21.73 µm |
| Cross-sectional Area | 737.79 µm² |
| Flow Velocity | 22.590 mm/s |
| Reynolds Number | 0.5 |
About Microfluidic Channel Design
Designing microfluidic chip channels requires optimizing on-chip flow conditions, controlling shear stress for biological applications, and balancing fabrication constraints with performance requirements. This tool helps you size rectangular channels to achieve desired hydrodynamic behavior.
Wall Shear Stress in Rectangular Channels
For fully developed laminar flow in a rectangular channel, the maximum wall shear stress at the channel walls is given by:
where µ is fluid viscosity (Pa·s), Q is volumetric flow rate (m³/s), w is channel width (m), and h is channel height (m). This formula assumes w >> h (high aspect ratio).
Hydraulic Diameter and Reynolds Number
The hydraulic diameter characterizes channel geometry for flow analysis:
The Reynolds number determines flow regime (laminar vs. turbulent):
For microfluidics, Re is typically < 100, ensuring laminar flow with minimal mixing. Higher Re may cause transition to turbulent flow (Re > 2000).
Shear Stress in Biology and Chemistry
- Cell mechanotransduction: Endothelial and blood cells respond to shear stress. Typical physiological shear is 1–10 Pa; high-shear applications use 20–100 Pa.
- Particle alignment: Cells and fibers orient under flow. Design channels to maintain target shear without exceeding lysis thresholds (often 50–200 Pa for mammalian cells).
- Molecular interactions: Low-shear (0.1–1 Pa) preserves cell–cell contacts; high-shear (10–100 Pa) enhances mixing and residence-time control.
Design Workflow
- Define target shear: Based on biological or chemical requirements, choose target wall shear stress.
- Select aspect ratio: Higher w/h ratios reduce pressure drop and fabrication difficulty. Typical range is 2:1 to 10:1.
- Calculate dimensions: Use this tool to find width and height meeting shear and aspect ratio constraints.
- Verify Reynolds number:Ensure Re < 2000 for laminar operation. If Re is too high, reduce flow rate or increase channel size.
- Fabrication check: Verify dimensions are achievable with your chosen process (lithography, 3D printing, molding).
Practical Considerations
- Aspect ratio limits:Fabrication resolution typically limits minimum feature size. High aspect ratios (w/h > 10) become difficult to fill without voids.
- Flow distribution: Multiple parallel channels require careful input/output design to balance flow. This tool assumes a single, uniform channel.
- Entrance effects: Shear develops over ~0.05 × Re × Dh length. Account for entrance length in long designs.
- Temperature effects: Viscosity changes with temperature. Check viscosity at your operating condition (e.g., 37°C for cell culture, 20°C for bench tests).
- Non-Newtonian fluids: Blood and other biofluids show shear-thinning. This tool assumes Newtonian fluids; use tabulated or measured viscosity values.
Ready to fabricate your microfluidic chip?
From rapid prototyping in 3D-printed resin to production-scale injection moulding in COC and COP. Upload your design or get in touch.