title: Microfluidic sedimentation cytometer for milk quality and bovine mastitis monitoring.
abstract: We report a rapid, low-cost, portable microfluidic sedimentation cytometer (SeCy) for assessing the somatic cell count and fat content of milk in 15 min using a "sample-in, answer-out" approach. The system consists of 12 independent microfluidic devices, essentially flattened funnel structures, fabricated on the footprint of a single plastic compact disc (CD). Each funnel structure holds 150 μL of milk, has an inlet for milk filling and an outlet for air to escape, and ends in a narrow, closed-end microfluidic channel that facilitates packing of the cells into a column whose length is proportional to cell count. The closed-end channel provides accurate cell counts over the range 50,000->3,000,000 cells per mL. The assay separates cells and fat globules based on their densities (by differential sedimentation), concentrating white cells in the closed-end channel near the outer rim of the CD for estimation of total "cell pellet" volume, while fat globules move toward the center of disc rotation, forming a fat "band" in the funnel. After adding milk to two or more microfluidic devices, the CD is loaded onto a custom-built reader unit that spins the disc for 15 min. Two low-cost microscopes in the reader image the centrifuged cell pellet and the fat band, providing a sufficiently accurate cell count to diagnose mastitis and measuring fat content as an indication of health and nutritional status.
authors.affiliation: Biomedical Diagnostics Institute, National Centre for Sensor Research, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Garcia-Cordero
authors.forename: Louise M
authors.initials: LM
authors.lastname: Barrett
authors.forename: Richard
authors.initials: R
authors.lastname: O'Kennedy
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Ricco
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002452:Cell Count; D003584:Cytological Techniques / Q000191:economics / Q000295:instrumentation*; D008414:Mastitis, Bovine / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D046210:Microfluidic Analytical Techniques / Q000191:economics / Q000295:instrumentation*; D008892:Milk / Q000166:cytology* / Q000378:metabolism / Q000592:standards; D019095:Point-of-Care Systems; D011786:Quality Control; D013997:Time Factors