| abstract |
A cell counting device for estimating the number of photoactive cells in a sample 1, comprises a chamber 70 for receiving the sample, and at least one light source to generate at least one pulse of light and to emit the light towards a section of the chamber, which section comprises a sub-sample of the sample. The cell counting device also comprises a light detector to receive a light emitted from the sub-sample and to generate an electronic signal associated with the received light. A controller estimates the number of photoactive cells in the sample by calculating the distribution of variable fluorescence [Fv] values of a predetermined number of sub-samples about the mean Fv, value. The device may operate in a discrete-sample mode, in which a blocking member 195 is provided. The device may also operate in a stop-flow mode (see fig 8b), in which another blocking member (190, fig 8b), is provided. In the stop-flow mode a tap 215 is used to control the cell counting device to continuously allow discrete samples to enter and leave the chamber. |