Optical vortex tracking microrheology of turbid viscoelastic tissue

We propose a novel optical microrheology technique that assesses tissue viscoelasticity by tracking the stochastic motion of optical vortices in speckles from turbid tissues. We validate the optical vortex tracking microrheology by illustrating the universal inverse relation between vortex displacements and the viscoelastic modulus. Moreover, we notice the phase angle of the viscoelastic sample is directly related to the vortices subdiffusion exponent. We also observe that the subdiffusion of optical vortices exhibits diverse characteristics for homogeneous and inhomogeneous samples. We believe the optical vortex tracking microrheology may find wide applications in different clinical scenarios like localizing tumors and fabricating biomaterials.