2023 Volume 23 Issue 9 Pages 491-498
Microrheology (MR) using optical trapping and laser interferometry is particularly useful for biological samples whose rheology remarkably depends on time and length scales. However, it has been challenging to measure samples like living cells that exhibit large fluctuations (flow) and can be damaged by laser light. Recently, with the feedback control of the optical-trapping force and the probe position, it has become possible to conduct precise, minimally invasive MR measurements of soft matter and living samples. In this paper, after explaining these latest techniques, we will present examples of measurements: the linear viscoelasticity within living cells, and the force-induced nonlinear fluctuations in the in vitro cytoskeleton.
