Passive Microfluidic Cell Sorting
Passive microfluidic cell sorting equipment can be used as a tool for efficient cell sorting with high resolution, which uses the advantages of microfluidic technology to sort and separate biological cells. The passive microfluidic cell sorting chip does not require any external force to sort cells, and is based on the forces exerted on the cells in the microchannel, such as inertial force and Dean force, or geometric patterns.
Continue reading to learn about Alfa Chemistry's passive microfluidic sorting platforms.
Inertial Microfluidics
The inertial microfluidic device utilizes the two main forces experienced by the cells in the microfluidic channel: inertial force and Dean force, which brings two kinds of cell sorting equipment, namely linear channel cell sorting and curved channel cell sorting.
Inertial microfluidic cell sorting in linear microchannels
The fluid flow in the microchannel of the inertial microfluidic chip is related to the Reynolds number, so the laminar flow can be precisely controlled and manipulated. In linear microchannels, flowing cells and particles will be subjected to inertial forces. This force can cause cells to migrate across the channel until they reach an equilibrium point.
This stable point depends on cell characteristics and causes cells with different characteristics to differentiate in the microchannel. The chip needs to be long enough to ensure that the battery has enough time to reach the equilibrium point.
Inertial microfluidic cell sorting in curved microchannels
The centrifugal force in the curved channel causes lateral pressure distribution, which in turn leads to the formation of this Dean flow. Dean flows usually appear in the form of two or more laterally counter-rotating vortices. There are many benefits in microfluidic sorting: they can help cells reach equilibrium faster and reduce the length; the bend and spiral shape of the chip also reduces the footprint of the device.
| Flow rate | Throughput | Design | Sheath-flow | |
|---|---|---|---|---|
| Straight Channel | Low/medium | Low/medium | Easy | No |
| Curved Channel | High | High | Moderate | No |
Deterministic Lateral Displacement
The deterministic lateral displacement (DLD) cell sorter has a very fine resolution (down to 10nm) for cell separation, depending on the geometric characteristics of the microchannel. In the DLD chip, the unit larger than the critical diameter moves laterally, while the smaller unit does not significantly change its path. By repeating this operation in each subsequent row, the distance between the large cell and the smaller cell will increase, and they will separate.
References
- Dincau B. M, et al. (2018). “Deterministic Lateral Displacement (DLD) in The High Reynolds Number Regime: High-throughput and Dynamic Separation Characteristics.” Microfluidics and Nanofluidics. 22: 59.
- Warkiani M. E, et al. (2016). “Ultra-fast, Label-free Isolation of Circulating Tumor Cells from Blood Using Spiral Microfluidic.” Nature Protocols. 11: 134-148.
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