A compact, optofluidic system for measuring red blood cell concentration

We developed a compact, single-cell imaging system for measuring red blood cell (RBC) concentration from diluted, whole blood samples. Key element of the design is the integration of a microfabricated lens array with a commercial haemocytometer. To image large areas and therefore a larger number of cells, the field of view (FOV) can be adjusted by simply increasing the thickness of the haemocytometer coverslip. We used a FOV = 200 μm, corresponding to a resolution of 0.53 μm, to demonstrate RBC counting: counts obtained from our system were in excellent agreement with counts obtained from standard microscopy and flow cytometry over a range of dilution factors.