ENGINEERING
Inertial Microfluidics for Cell Focusing and Sorting
Most microfluidics runs at very low flow rates where inertia is negligible. Inertial microfluidics deliberately turns the flow up so that inertial forces line particles into tight streams — enabling fast, label-free sorting. Here is how.
Inertia at the microscale
At higher (but still laminar) flow rates, inertial lift forces push suspended particles to specific equilibrium positions across the channel. Particles of different sizes settle into different positions, so they can be separated.
Spiral channels and Dean flow
Curved and spiral channels add a secondary "Dean" circulation that, combined with inertial lift, focuses particles by size into distinct streams that exit through separate outlets — a popular design for continuous sorting.
Why it is useful
- High throughput — runs fast, processing large sample volumes.
- Label-free — separates by size and shape, no tags needed.
- Simple — passive, pump-only, no external fields.
Applications
Circulating tumour cell enrichment, blood cell separation, cell-cycle synchronisation and sample cleanup. It complements active methods such as acoustofluidics and dielectrophoresis.
Frequently asked questions
What is inertial microfluidics?
A technique that uses fluid inertia at moderate flow rates to focus and separate particles or cells by size into defined positions in a channel, label-free and at high throughput.
How do spiral channels sort cells?
Curved channels create a secondary Dean flow that, with inertial lift forces, focuses different-sized particles into distinct streams that can be collected at separate outlets.
What are the advantages of inertial microfluidics?
High throughput, label-free separation, and simple passive operation using only a pump, with no external fields or tags.
Sort by flow alone
Designing an inertial sorter?
Channel geometry is everything for inertial focusing. Upload your design for a quote, or book a call.
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