Cell sorting facs machine

A FACS (Fluorescence-Activated Cell Sorting) machine is a device that sorts individual cells based on fluorescence, enabling precise isolation of specific cell populations.

About this subject

Fluorescence-Activated Cell Sorting (FACS) technology represents a cornerstone in cellular and molecular biology. Evolved from flow cytometry, FACS enables the isolation of individual living cells based on optical properties such as size, granularity, and specific fluorescence emitted from labeled markers. The principle involves cells flowing in a fine laminar stream where each cell is interrogated by one or more lasers. Scattered light and fluorescence are detected by photodetectors, and the electronic system decides within milliseconds whether to charge and deflect the cell into a specific collection tube.

Antibodies conjugated to fluorochromes are commonly used to label surface proteins, organelles, or even DNA. FACS is widely applied in immunology to sort T or B cell subsets, in oncology to purify circulating tumor cells, and in stem cell biology to enrich rare populations. The purity and viability of sorted cells typically exceed 90%, which is critical for downstream applications such as cell culture, RNA sequencing, or functional assays.

Interestingly, FACS was invented in the 1960s by Leonard Herzenberg and colleagues at Stanford University. Since then, machines have evolved to sort up to 70,000 cells per second. Modern instruments may use multiple lasers (up to 5 or more) and detect dozens of parameters simultaneously, enabling complex multiparametric analyses. Despite high costs and the need for trained operators, FACS remains indispensable in research labs and clinical diagnostics, such as CD4 lymphocyte counting in HIV patients.

The tilt-shift effect in the image (giving a miniature appearance) does not alter the instrument's function but can visually emphasize its complexity. It is important to note that FACS differs from non-sorting flow cytometry because sorting requires a droplet deflection system and high-speed electronics. Laboratory safety demands precautions against aerosols and proper disposal of biological waste, along with daily calibration using reference beads.

Frequently Asked Questions

What is a FACS machine used for?

FACS sorts individual cells based on fluorescence, allowing isolation of specific populations for downstream applications such as cell culture, sequencing, or functional assays.

What is the difference between flow cytometry and FACS?

Flow cytometry only analyzes cells, while FACS (cell sorting) physically separates them by deflecting electrically charged droplets into different collection tubes.

How long does it take to sort cells on a FACS?

It depends on the machine speed and target population frequency. Modern machines can sort up to 70,000 cells per second, but sorting rare populations may take hours.