Active Microfluidic Cell Sorting

Active microfluidic cell sorting uses external force fields for cell sorting, such as acoustic, magnetic, or dielectric forces. Alfa Chemistry has developed active methods to improve the efficiency, accuracy, and specificity of microfluidic cell sorting devices. The modularity and versatility of the microfluidic chip can enable various external sources to be integrated with the chip.

Read on to learn about Alfa Chemistry's active microfluidic sorting platforms.

Fluorescence-activated Cell Sorting

The FACS system separates selected cell populations from heterogeneous mixtures based on the fluorescence and light scattering characteristics of each cell. It can track and classify different fluorescent cell surface markers or cytoplasmic biomolecules with fluorescent protein tags in one run.

Besides, we have used fluorescence-assisted sorting of cells in the microfluidic device, which can incubate heterogeneous samples containing different cell types with antibodies that specifically bind to the fluorophore, and combine the fluorescently labeled targets. The cells are separated when they are introduced into a microchannel with a laser and an optical detector.

Magnetic-activated Cell Sorting

The MACS system incubates samples containing different types of cells with specific antibodies coupled to magnetic particles, and then directs the resulting magnetically labeled target cells into a channel with an active magnetic field for separation. Magnetic microfluidic chips for cell sorting and separation are known for their speed and simplicity. Microfluidic-based magnetically activated cell sorting technology (μMACS) greatly reduces the number of reagents, improves purity, flux, and continuous flow recovery. Permanent magnets are cheap, and they can be embedded in microfluidic chips.

Dielectrophoresis Microfluidic System

DEP is caused by the interaction between the applied non-uniform electric field and the non-uniform distribution of dipoles induced in the polarized particles suspended in the buffer solution. We use this phenomenon to separate and sort particles and cells in microfluidic systems. In the presence of an electric field, each cell shows a difference in dielectrophoresis activity, which enables them to be effectively separated and sorted. The advantage of our microfluidic chip is that both negative and positive forces can be applied.

Figure.1 Schematic representation of active microfluidic systems: (A) Dielectrophoretic (DEP) devices; (B) Acoustofludic devices. (Sivaramakrishnan M , et al. 2020)

Acoustic Microfluidic Separation

Acoustic fluid separation is based on the interaction of electromechanical induced acoustic waves with fluids and inclusions in fluids. Most of these microfluidic devices use interdigital transducers that can generate sound waves embedded under the microchannels. Sound waves can create pressure nodes along the microchannel, which can cause cells to move to a specific area of the channel. Continuous exposure of cells to these sound waves causes the cells to be sorted according to their characteristics. We use sound to make microfluidic chips for cell sorting, which can be stacked to achieve multi-level cell sorting.

Reference

• Sivaramakrishnan M, et al. (2020). "Active Microfluidic Systems for Cell Sorting and Separation." Current Opinion in Biomedical Engineering. 13: 60-68.

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