Determination of microbial load and somatic cell count in milk with lab-on-a-chip (LOC) device

Lab-on-a-chip (LOC) systems that has been emerged in the last 20 years and used for processing the fluid in a microchannel structure at microliter levels are alternative to the traditional methods. LOC devices can make complex analysis more efficient with lower cost, lower energy and lower chemical consumption as compared to traditional systems because of the unique properties they have, and they make valuable options for many applications (biomedical, food, chemistry, medicine, pharmacy, agriculture, etc.) in these aspects. In addition, these systems are suitable for automation and have potential to be portable. Especially in some cases in dairy industry, taking the results of the analysis quickly has a great importance for the company. For this reason, LOC technology is very important with their features of quick response in microbiological analysis, not skilled personel required, low amount of sample, etc. in dairy industry. The objective of the study is to develop a LOC device able to count live bacteria and somatic cells in whole milk. For this purpose, a polydimethylsiloxane (PDMS) chip with a channel size of 300μm × 60μm and a overall size of 3cmx1cm has been produced, firstly. Cells/bacteria labeled with fluorescent dye in milk were counted with LOC device and then the results were compared with the real cell concentration/ the traditional method. It has been found that LOC devices can be counted somatic cells at different concentrations with 85% accuracy and bacteria at different concentrations with 90% accuracy, in a 20 minute run for each analysis. LOC device designed in the study has an overall dimension of 25cmx25cmx25cm and weighs approximately 9 kg (included equipments). The cost of the counting for single test is estimated as 20 TL. It is expected that the study will contribute to the scientific literature and also portable LOC device developed with local resources will contribute to domestic facilities.