A portable somatic cell counter based on a multi-functional counting chamber and a miniaturized fluorescence microscope.

A somatic cell count is the concentration or density of somatic cells in milk, and is an important indicator for monitoring mastitis incidence and milk quality in the dairy industry. Managing and controlling mastitis based on somatic cell counts can help ensure high milk quality and yield. A major challenge when translating existing cell counting methods to such application is that they require off-chip sample preparation and complicated sample and reagent delivery steps that cannot be easily performed in resource-limited settings such as dairy farms. Here, we describe an integrated cell counting platform that enables automatic sample delivery into a cell counting chamber and on-chip sample preparation without requiring any off-chip processes, and that simultaneously provides a miniaturized, hand-held fluorescence device for the identification of fluorescently-labelled somatic cells. Our platform thus allows simple, rapid and accurate enumeration of somatic cells in milk. We successfully demonstrated its capability of counting somatic cells in milk, which can be easily performed even by non-experts without additional instrumentation. The platform represents a promising tool for everyday milk-quality tracking and for controlling mastitis occurrence.