Automated Electrowetting-based Nanobiopsy System for Adherent Cells

cell nanobiopsy based on nanopipette is an effective approach to demonstrate the heterogeneity of cells and understand the roles of organelles, mRNA, and DNA of living cells. However, the manual operation of single-cell nanobiopsy has several drawbacks such as low throughput and operator variability. This paper proposes an automated nanobiopsy system containing aspiration under electrowetting based on two immiscible electrolytic solutions(TIES), cell detection, tip positioning, and contact detection for automated single-cell nanobiopsy. The physical model of TIES-based electrowetting was reported to describe the principle of aspirating fluid and evaluated to extract aqueous solution. The cell detection algorithm was utilized to obtain the nanobiopsy position of cells and evaluated on human umbilical cord vein endothelial cells (HUVEC), which provided an average of 90.8% true-positive rate (TPR) and 10.35% false-positive rate (FPR). The focus plane and tip of nanopipette were located by tip positioning algorithm based on template matching. The contact detection based on ion current feedback was employed for obtaining the distance between cells and the focus plane. Finally, the automated system accurately achieved single-cell nanobiopsy in ten to hundred living cells, which had 55.9% survival rate after sampling 220 cells totally.