Skip to main content

Cellometer K2 Fluorescent Cell Counter

The Cellometer™ K2 fluorescent cell counter is an advanced, dual-fluorescence cell counter with built-in assays and cell types for the analysis of hepatocytes, stem cells, splenocytes, tumor suspension, and other complex primary cells. A 21 CFR Part 11 module is available.

For research use only. Not for use in diagnostic procedures.


The Cellometer K2 fluorescent cell counter, powered by Matrix software, utilizes brightfield imaging and dual-fluorescence imaging to quickly and accurately identify and count individual cells. Cell count, concentration, diameter, and % viability are automatically calculated and reported.

The Cellometer K2 cell counter provides:

  • Dual fluorescence and brightfield imaging – stain only nucleated cells for accurate count and viability information
  • Fast results – count, size, concentration, and viability calculations in <60 seconds
  • Analysis of complex samples – designed for analysis of complex and messy samples including whole blood, peripheral blood, cord blood, and bone marrow
  • 21 CFR Part 11 ready – optional add-on that includes an audit trail, user access control, and digital signature
  • Multiple fields of view – increased accuracy with the ability to capture one, four, or eight images per sample
  • Built-in predefined assays – quickly analyze viability, apoptosis, and transfection efficiency
  • Built-in cell types – includes saved parameters for over 400 cell types
  • Small sample volume – only 10 µl of cell sample required
  • Configurable reports – includes predefined reports with the ability to create new ones with graphs, images, charts, and tables
k2 matrix software screenshot

Additional product information

Count a variety of samples - from cell lines to primary samples
k2 cell image examples


The Cellometer K2 can be configured to handle a variety of cell types, including primary cells, tumor digest, insect cells, cell lines, fragile cells, and more at low or high concentrations.

Predefined assays and cell types

Take the guesswork out of setting up your cell quantification experiments. The Cellometer K2 includes a library of commonly-used assays and cell types with predefined settings to help improve consistency of results. Conveniently build and modify assays and cell types to help match your specific experimental requirements.

k2 predefined assays


hemocytometer grid
Capture multiple fields of view

Capture one, four, or eight images per sample. The instrument default is set to four images, which is the equivalent of six quadrants on a hemocytometer. Eight images are equivalent to twelve quadrants on a hemocytometer. The ability to capture multiple images improves the cell counting dynamic range and reliability of results.

Dual-fluorescent staining for clumpy cells

The fluorescent image shows bright green AO-positive hepatocytes declustered by the Cellometer K2 algorithm. Red circled hepatocytes are PI-positive (dead) while free nuclei are not counted.

clumpy hepatocytes aopi
Predefined and customizable reports

Use default or customized reports based on the data and images you want to be included for your specific experimental needs. Automatically export images and data reports including CSV, Excel, Word, or PDF files. Perform statistical analysis for a wide range of parameters such as average, variance, min/max, and standard deviation of cell size.

k2 custom report histogram


k2 custom report scatter plot
21 CFR Part 11-ready

An optional module can be purchased to facilitate 21 CFR Part 11 compliance. The additional module comes with the following features:

  • User login with passwords
  • User assigned permissions
  • Audit trail
  • Error log files
  • Electronic signatures
k2 matrix 21cfr screen


Live/dead nucleated cell counts using dual-fluorescence

Why dual-fluorescence?

Because brightfield cell counting does not differentiate nucleated from non-nucleated cells and Trypan blue staining is not as easy to detect as fluorescent staining, dual-color fluorescence is strongly recommended for reliable viability analysis for primary cells. The K2 is equipped with standard assays for dual-fluorescence analysis of a variety of cells stained with Acridine Orange and Propidium Iodide (AO/PI).

The AO/PI method

Acridine Orange (AO) is a nuclear staining (nucleic acid binding) dye permeable to both live and dead cells. It stains all nucleated cells to generate green fluorescence. Propidium Iodide (PI) can only enter dead cells with compromised membranes. It stains all dead nucleated cells to generate red fluorescence. Cells stained with both AO and PI fluoresce red due to quenching, so all live nucleated cells fluoresce green and all dead nucleated cells fluoresce red.

brightfields vs aopi
The brightfield image on the left shows the combination of nucleated cells, red blood cells, and platelets present in the sample. The red blood cells are not visible in the fluorescent image on the right, only the live (green) and dead (red) nucleated cells are counted.

No interference from red blood cells, platelets, or debris

The dual-fluorescence AO/PI method utilizes nuclear staining dyes that bind to nucleic acids in the cell nucleus. Because most mature mammalian red blood cells do not contain nuclei, only live and dead mononuclear cells produce a fluorescent signal. There is no need to lyse red blood cells, saving time and eliminating an extra sample preparation step. Red blood cells, platelets, and debris are not counted in the fluorescent channels.

Analysis of clumpy and irregular-shaped cells

NCI-60 and clumpy MCF-7 cells

NCI-60 is a group of 59 human cancer cell lines (originally 60) developed by the National Cancer Institute (USA) for screening purposes.

  • 57% of the NCI-60 cell lines are clumpy, contain debris, or display large variations in cell shape or size
  • All 59 NCI-60 cell lines have been successfully validated on the Cellometer cell counter

Clumpy cells

clumpy cells
The MCF-7 breast cancer cell line can be very clumpy. The Cellometer pattern-recognition software identifies and counts individual cells within these cell clumps for reliable analysis (shown above).

Irregular-shaped cells

count irregular shaped cell automatically
The Cellometer cell roundness setting can be adjusted for recognition and counting of irregular-shaped cells, such as RD cells and activated T-cells.
10x faster than manual counting
Hemocytometer under microscope

Counting 1 x 106 cells takes approximately 5 minutes with a manual hemacytometer. Counting live and dead cells sometimes takes twice as long. The Cellometer K2 cell counter calculates cell count and concentration for live and dead cells and % viability in just 60 seconds.

Improve data reliability and consistency:

  • Reduce judgment errors
  • Reduce interference from RBCs
  • Reduce recording & calculation errors
  • Reduce counting time - run more experiments
Imaging / counting chambers: no washing or contamination

We offer two different disposable counting slides, one with protective coverings on both sides and a ready-to-use option packed in microscope slide boxes. Disposable slides offer the advantages of time-saving, since no washing is required, reduced risk of contamination and reduced biohazard risk to users.

System includes
  • Cellometer K2 instrument
  • Cellometer software
  • Two standard fluorescence optics module
  • Power supply
  • USB 2.0 connection cable
  • Phone/online applications support during set-up
Available accessories
  • PC Laptop
Imaging performance
  • Cell Size: 4-90 microns
  • Conc. Range: 105 – 107 cells/ml
  • Brightfield imaging, fluorescent imaging and pattern-recognition software to quickly and accurately decluster, identify and count individual cells.
Instrument specifications
  • Weight: 23.0 lbs. (10.4 kg)
  • Dimensions: Width: 6.0” (15.2 cm), Depth: 8.5” (21.6 cm), Height: 14.0” (35.6 cm)
  • Input to Power Adapter: 100-240 VAC, 50/60 Hz, 1.0A
  • Output to Instrument: 12 VDC, 3.34A
PC / Laptop Minimum Requirements: (If purchasing Cellometer without PC laptop)
  • Windows 10, 64-bit
  • Intel® Core i7, 2.0 GHz processor
  • 16GB RAM (or higher)
  • NVIDIA P1000 GPU (equivalent or better)
Available fluorescence optics modules
  • Excitation / Emission: 470nm/535nm
  • Example Fluorophores: Acridine Orange, CFDA, FITC
  • Excitation / Emission: 540nm/660nm
  • Example Fluorophores: Propidium Iodide (PI), Ethidium Bromide, 7-AAD




1-6 of 31 Resources
eBook Icon
10 key factors to improve your cell counting results

Cell counting plays a crucial role in the development and manufacturing of cell and gene therapies as well as regenerative...

Application Note Icon
Application Note
A quick and direct Candida albicans lysis efficiency comparison using the Cellometer X2 fluorescent cell viability counter.

Application note for Cellometer X2Candida albicans lysis efficiency

Application Note Icon
Application Note
Accurate cell counting for single cell sequencing platforms using the Cellometer K2 fluorescent cell counter.
Flyer Icon
Automated cell counters for single cell sequencing
Brochure Icon
Automated cell counting and image cytometry solutions brochure
Flyer Icon
Cellometer K2 fluorescent cell counter - designed for precise cell counting and fluorescent analysis
SDS, COAs, Manuals and more Illuminator

SDS, COAs, Manuals and more

Are you looking for technical documents for this product. We have housed them in a dedicated section., click on the links below to explore.

Scroll Icon