This paper describes a micro device which applies cyclic strain to focal adhesions of a cell. In recent years, evidence has been growing that focal adhesions act as mechanosensors of cells which convert mechanical force into biomechanical signaling. However, there are no effective micro devices which can directly apply mechanical stimulation to each focal adhesion. Here we develop a micropillar substrate embedding micron-sized magnetic particles and enabling the micropillars to be deflected by external magnetic field. The combination of long and short micropillars produces the difference of deflection between them and enables the micropillars to apply strain to a cell. The long pillars were periodically deflected at the amplitude of approximately 1.4 μm whereas most of short pillars were not deflected. Using the magnetic micropillar substrate, we observed the deformation of an osteoblast cell at its focal adhesions. The findings indicate that the present micro device can be used for investigating mechanosensing systems of a cell.
