ENGINEERING
Concentration Gradient Generators in Microfluidics
Many biological questions — how cells respond across a range of drug doses, or migrate toward a chemical — need a controlled concentration gradient. Microfluidic gradient generators produce them precisely and reproducibly. Here is how.
Why gradients matter
Cells in the body sense chemical gradients — in chemotaxis, morphogenesis and signalling. Recreating a defined, stable gradient lets researchers study dose-response and cell migration in a single, well-controlled experiment.
Flow-based ("Christmas tree") generators
The classic design is a branching network that repeatedly splits, mixes and recombines two inlet streams, producing a staircase of concentrations across a set of parallel outlets. It depends on predictable laminar flow and complete mixing at each stage.
Diffusion-based generators
A source and a sink separated by a diffusion region (often a gel or membrane) set up a stable, shear-free gradient — gentler on cells because they are not exposed to flow shear.
Applications
Drug dose-response screening, chemotaxis and cell-migration assays, stem-cell differentiation studies and toxicity testing all use gradient generators.
Design considerations
- Channel lengths long enough for complete mixing at each junction — estimate with our diffusion mixing tool.
- Shear stress on cells, especially in flow-based designs.
- Gradient stability over the duration of the experiment.
Frequently asked questions
What is a concentration gradient generator?
A microfluidic structure that produces a defined, reproducible range of concentrations across a chip, used to study dose-response and cell migration.
How does a Christmas-tree gradient generator work?
A branching network repeatedly splits, mixes and recombines two input streams so that a staircase of concentrations emerges across parallel outlet channels.
What is the difference between flow-based and diffusion-based gradients?
Flow-based generators mix streams to set concentrations but expose cells to shear; diffusion-based generators use a shear-free diffusion region, which is gentler on cells.
What are gradient generators used for?
Drug dose-response screening, chemotaxis assays, stem-cell differentiation and toxicity testing.
Defined gradients, every time
Designing a gradient generator?
We turn gradient designs into precise, reproducible chips. Upload your design for a quote, or book a call.
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