High-Throughput Separation of <i>Alexandrium</i> Cells Based on Deterministic Lateral Displacement Arrays With Different Post Shapes

Alexandrium is a common red tide alga, and most incidents of poisoning are attributed to it. Therefore, the research on Alexandrium is very crucial for mitigating red tide disasters and safeguarding the marine environment. However, Alexandrium algae cells in natural environments or cultures are frequently contaminated by impurities or hybrid algae. Therefore, the separation and purification of Alexandrium cells are the essential prerequisites for further research. Herein, a high-throughput microalgae cell separation method based on the principle of deterministic lateral displacement (DLD) has been proposed, which can achieve high-throughput separation without additional external force required. First, the relationship between the micropillar shapes, chip parameters, and the separation threshold was analyzed. Based on this, two types of chips with different micropillar shapes, circular and triangular, were designed. Then, three types of algae cells, Alexandrium, Chlorella, and Thalassiosira weissflogii, were selected as the samples. The experimental results indicate that both chips can achieve satisfactory separation performance, with a separation efficiency exceeding 80% and a maximum throughput of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300~\mu $ </tex-math></inline-formula>L/min. Furthermore, the performance of the two chips was compared and analyzed in terms of separation efficiency, throughput, flow resistance, and stability. The results indicate that the triangular micropillar chip outperforms the circular micropillar chip in the above aspects. To our knowledge, this is the first time that DLD technology has been applied to the separation and purification of Alexandrium cells. These findings will contribute to the research and utilization of Alexandrium cells, red tide disaster prevention, and marine ecological environment protection.