Optical Detection of Different Single Biological Cells in an Integrated Projection Cytometer

In this paper we present results on optical detection of single biological cells in an integrated projection cytometer. The sensor system consists of an integrated photodiode, a flow cell for positioning the sample flow, and an external laser diode that is used to illuminate the flow channel containing the photodiode. When a cell passes by, a distortion in the optical path is caused which is detected with the photodiode. The sensor has already been successfully tested with polystyrene particles. In this contribution we show for the first time results for two different cells types: bakers yeast and Chinese hamster ovary (CHO) cells, which have a mean diameter of 4 and 15 mum, respectively. The experiments demonstrate that the two cell types can be distinguished easily. Because of their optical transparency, both cell types show an increase in light intensity which is explained by a lens effect focusing light onto the sensitive area. CHO cells show a higher peak response because of their larger size.