Scaling Effects on Single‐Cell Manipulation Using Magnetic Forces at Edge of Flat Plate With Elliptically Micro‐Projection

Single‐cell manipulation is needed for various cellular analyses and biomedical applications. In the conventional single‐cell manipulation methodology, cells are the center of a flat dish or hollow space, where the medium spontaneously penetrates. However, manipulation at the edge of the plate, where the flow of the medium is interrupted by its surface tension, has not yet been shown. In this study, we manipulated single cells labeled with magnetic nanoparticles at the edge of a projecting microfabricated plate under a magnetic field, which offer a less invasive method for cellular analyses, not limited by the shape of the culture devices. As a cell is affected by both the surface tension of the medium and magnetic force, we investigated the effects of the shape and scale of the projection on cell motion. Owing to energy minimization between the liquid–air and solid–liquid interfaces determined by the structure of the projection, the area of solution spreading in the projection converged, and we obtained design guidelines for the projection that enabled cell manipulation. Demonstrating accuracy in single‐cell manipulation on a microfabricated flat plate with different projection shapes contributes to developing single‐cell analyses, including applications such as single‐cell‐based polymerase chain reactions.