Separation of microalgae cells in a microfluidic chip based on AC Dielectrophoresis

BACKGROUND: Microalgae is an important natural resource with extensive applications in various fields, such as health products, animal feed, biopharmaceuticals, and clean energy. However, before the research and utilization of microalgae resources, the microalgae cells of interest must be separated from hybrid strains and bacteria. The traditional method of microalgae separation requires manual labor under the microscope that is time-consuming and labor-intensive. RESULTS: Herein, a novel microalgae cell separation method based on the dielectrophoresis (DEP) technique was proposed. A unique DEP separation chip with a 3D electrode was designed. Chlorella and Closterium were used as the experimental samples to verify the effectiveness of the proposed method because they have similar volumes and very different electrical properties. Within a certain frequency range, Chlorella suffers from negative dielectrophoresis (nDEP) force and Closterium suffers from positive dielectrophoresis (pDEP) force, so their separation can be achieved. The separation efficiency exceeded 90%. In addition, the DEP response of the Chlorella and Closterium were studied, and the DEP spectra of the two microalgae cells were obtained. Moreover, the effects of DEP force on cell viability under different voltages and frequencies were experimentally analyzed. CONCLUSION: These findings will contribute to DEP technology, to the portable and harmless separation of microalgae, and to research on the dielectric properties of microalgae cells. (C) 2022 Society of Chemical Industry (SCI).