Dielectrophoretic–inertial microfluidics for Symbiodinium separation and enrichment

In the marine environment, the symbiotic relationship between Symbiodinium and corals plays a pivotal role in coral growth and development. Against the backdrop of widespread coral bleaching due to the global climate change, the facile and efficient separation and enrichment of different strains of Symbiodinium hold significant importance for studying coral bleaching. This paper aims to report a platform that integrates dielectrophoretic and inertial forces for the separation and enrichment of Symbiodinium, comprising two modular components: a separation module and an enrichment module. Within the separation module, distinct strains of Symbiodinium undergo preliminary stratification in a contraction–expansion microchannel under the influence of inertial forces. Dielectrophoretic forces generated by the indium tin oxide electrodes divert them toward different outlets, achieving separation. In the enrichment module, the Symbiodinium collected from outlets is rapidly focused through a contraction–expansion microchannel and high-purity samples are concentrated through a single outlet. Evaluating separation efficiency is based on the purity of collected Symbiodinium at the outlet under three different flow rates: 13, 16, and 19 μl/min, while the concentration of enriched Symbiodinium at 100, 200, 300, and 400 μl/min flow rates evaluates the effectiveness of the enrichment process. The experimental results demonstrate a separation purity of approximately 90% and an enrichment factor of around 5.5. The platform holds promise for further applications in the selection and targeted enrichment of high-quality coral symbiotic algae, providing essential research foundations for the conservation of coral ecosystems.