Editing Flow cytometry (section)

==Flow cytometers==
[[File:Cytometer.svg|thumb|upright=1.25|Schematic diagram of a flow cytometer, from sheath focusing to data acquisition.]]

Modern flow cytometers are able to analyze many thousands of particles per second, in "real time" and, if configured as cell sorters, can actively separate and isolate particles with specified optical properties at similar rates. A flow cytometer is similar to a [[microscope]], except that, instead of producing an image of the cell, flow cytometry offers high-throughput, automated [[Quantification (science)|quantification]] of specified optical parameters on a cell-by-cell basis. To analyze solid [[Biological tissue|tissues]], a single-cell suspension must first be prepared.{{cn|date=November 2021}}

A flow cytometer has five main components: a flow cell, a measuring system, a detector, an amplification system, and a computer for analysis of the signals. The flow cell has a liquid stream (sheath fluid), which carries and aligns the cells so that they pass single file through the light beam for sensing. The measuring system commonly uses measurement of impedance (or conductivity) and optical systems – lamps ([[mercury (element)|mercury]], [[xenon]]); high-power water-cooled lasers ([[argon laser|argon]], [[krypton laser|krypton]], dye laser); low-power air-cooled lasers (argon (488&nbsp;nm), red-HeNe (633&nbsp;nm), green-HeNe, HeCd (UV)); [[diode laser]]s (blue, green, red, violet) resulting in light signals. The detector and analog-to-digital conversion (ADC) system converts analog measurements of forward-scattered light (FSC) and side-scattered light (SSC) as well as dye-specific fluorescence signals into digital signals that can be processed by a computer. The amplification system can be [[linear]] or [[logarithmic scale|logarithmic]].{{cn|date=November 2021}}

The process of collecting data from samples using the flow cytometer is termed "acquisition". Acquisition is mediated by a computer physically connected to the flow cytometer, and the software which handles the digital interface with the cytometer. The software is capable of adjusting parameters (e.g., voltage, compensation) for the sample being tested, and also assists in displaying initial sample information while acquiring sample data to ensure that parameters are set correctly. Early flow cytometers were, in general, experimental devices, but technological advances have enabled widespread applications for use in a variety of both clinical and research purposes. Due to these developments, a considerable market for instrumentation, analysis software, as well as the reagents used in acquisition such as [[fluorescent labeling|fluorescently labeled]] [[antibodies]] have been developed.

Modern instruments usually have multiple lasers and fluorescence detectors. The current record for a commercial instrument is ten lasers<ref>{{Cite web|url=https://www.centenary.org.au/cen_resources/resources-equipment/|title=Resources & Equipment|website=Centenary Institute}}</ref> and 30 fluorescence detectors.<ref>{{cite web|url=http://www.bdbiosciences.com/us/instruments/research/cell-analyzers/special-order-products/m/cellanalyzersspecialorderproducts/analyzers |title=BD Biosciences – Special Order Products}}</ref> Increasing the number of lasers and detectors allows for multiple antibody labeling, and can more precisely identify a target population by their [[phenotypic]] markers. Certain instruments can even take digital images of individual cells, allowing for the analysis of fluorescent signal location within or on the surface of cells.{{Citation needed|date=August 2022}}