Cellular Force Measurement Using a Nanometric-Probe-Integrated Microfluidic Chip with a Displacement Reduction Mechanism

This paper presents noncontact nanometric positioning of a probe tip with high output force in a microfluidic chip. To measure cellular force in a microfluidic chip on the basis of cell deformation, we employed an on-chip probe with a magnetic drive method with actuation on the order of millinewtons. A reduction mechanism was proposed to realize nanometric resolution for positioning the probe tip. This mechanism utilizes a combination of springs with different stiffness levels and is driven by magnetic force. The performance of the prototype device was examined and results indicated that, as a measure of repetitive positioning accuracy, standard deviation of probe tip displacement was under 0.18 mu m. Deformation was successfully measured for an oocyte on the order of 0.1 mN, demonstrating, as a consequence, nanometric order noncontact actuation of the on-chip probe with high output force. Using this on-chip probe, cellular force measurement was achieved for the microfluidic chip.