Cytometers

Cytometers are instruments used to measure physical and chemical properties of cells and cellular components. They are employed in research and clinical settings to quantify cell characteristics, often at high throughput, and to analyze multiple parameters from individual cells.

The most common form is the flow cytometer, which analyzes cells as they flow in single file through an interrogation point illuminated by one or more lasers. Detectors collect forward scatter and side scatter signals, which provide information about cell size and internal complexity, as well as fluorescence emitted by labeled markers. By using fluorescent antibodies or dyes, flow cytometry can quantify multiple cellular features simultaneously, such as surface or intracellular proteins, viability, and functional states. Another class is the image cytometer, which uses automated microscopy and image analysis to extract morphological and molecular features from cells in wells or on slides.

Impedance-based cytometers, sometimes referred to as Coulter counters, count and size cells by detecting changes in electrical resistance as cells pass through a small aperture. These devices are widely used for routine blood cell counts and other particle measurements.

Outputs from cytometers typically include scatter plots, histograms, and multi-parameter data that enable gating and population analysis. Applications span clinical immunophenotyping, cancer diagnostics, stem cell research, microbiology, and plant biology, among others. Key considerations in cytometry include sample preparation, instrument calibration, spectral compensation for overlapping fluorescence, and proper data analysis to ensure accurate interpretation.