Quantifying local stiffness and forces in soft biological tissues using droplet optical microcavities.

Mechanical properties of biological tissues fundamentally underlie various biological processes and noncontact, local, and microscopic methods can provide fundamental insights. Here, we present an approach for quantifying the local mechanical properties of biological materials at the microscale, based on measuring the spectral shifts of the optical resonances in droplet microcavities. Specifically, the developed method allows for measurements of deformations in dye-doped oil droplets embedded in soft materials or biological tissues with an error of only 1 nm, which in turn enables measurements of anisotropic stress inside tissues as small as a few pN/μm.

Remote and autonomous temperature measurement based on 3D liquid crystal microlasers.

We demonstrate non-contact temperature measurement with one tenth of a kelvin precision at distances of several meters using omnidirectional laser emission from dye-doped cholesteric liquid crystal droplets freely floating in a fluid medium. Upon the excitation with a pulsed laser the liquid crystal droplet emits laser light due to 3D Bragg lasing in all directions. The spectral position of the lasing is highly dependent on temperature, which enables remote and contact-less temperature measurement with high precision.