Cell Counting and Imaging System Specifications

1. Optics and imaging

• Brightfield plus fluorescence, with at least two fluorescence channels such as AO and PI or AO and DAPI

• Objectives from 4X to 10X covering the counting area

• LED brightfield and independently controlled fluorescence channels

• Sensor of 5 megapixels or more imaging the whole area at once

• Single shot imaging rather than scanning, with each count within 10 seconds

2. Counting principle and precision: the key item

• Counting range from 1 times 10 to the 4 up to 1 times 10 to the 7 cells per millilitre, with dilution above that

• Repeatability with a coefficient of variation of 5 percent or better over ten repeats

• Deviation from manual haemocytometer counting within 10 percent

• The lower detection limit must be stated, since statistical error grows sharply below it

• Note: precision claims hold within a stated range, and 5 percent usually refers to mid range concentrations

3. Consumables and throughput

• Sample volume of 10 to 20 microlitres

• Dedicated single use slides or standard haemocytometers

• Cost per slide and whether third party slides are accepted should be stated

• Each count within 10 seconds including cleaning and changing samples

• Throughput around 60 to 100 samples per hour manually, higher with automated loading

4. Live and dead discrimination

• AO and PI double staining, green for live and red for dead, the most common method

• Trypan blue in brightfield, economical but requiring judgement and sensitive to debris

• Fluorescence resists interference and suits primary cells and dirty samples

• Whether label-free viability is supported should be clarified

• Debris and bubbles must be excluded automatically by the software

5. Analysis parameters

• Total, live and dead cell counts and viability percentage

• Cell diameter distribution with mean and histogram

• Aggregation rate and percentage of single cells

• Morphology parameters such as roundness and area

• Separate algorithms for yeast and algae where needed

6. Software functions

• Autofocus and automatic exposure

• Automatic concentration calculation with dilution factor input

• Result storage and history search linked to sample identifiers

• Retention of both original and annotated images

• Export to CSV, Excel and PDF reports

7. Data and compliance

• Tiered user access and operation logs

• 21 CFR Part 11 audit trail and electronic signature as options, needed in pharmaceutical and cell therapy work

• Results traceable to the original image and acquisition time

• LIMS integration by export or interface

8. Power and environment

• Power supply AC 220 V, 50 Hz

• Operating temperature 15 to 30 degrees Celsius

• Relative humidity up to 80 percent

• A compact body if it is to be used inside a biosafety cabinet

• Away from strong vibration, which affects autofocus

9. Where procurement goes wrong

• Only cell counter is specified without concentration range or precision, and low concentration samples carry large errors that invalidate the experiment

• Consumables are locked to the vendor without annual cost being stated, and running costs exceed the instrument price

• No fluorescence channels, so primary cells and dirty samples cannot be discriminated and manual counting returns