Fig. 1
From: Rheological properties of cells measured by optical tweezers
Definition of the variables in the cell rheology experiment. ξ(t) is the sample displacement, with amplitude ξ0, when an oscillatory movement is applied to the stage, with no optical forces acting on the bead, so that it just follows the stage displacement; x and ρ are the cell deformation and the bead displacement, respectively, when the laser is turned on and the stage is oscillating