High-speed assessment of liquid viscoelasticity in flow cytometry using nonlinear Brillouin spectroscopy

Brillouin microspectroscopy is a powerful tool for elasticity-sensitive non-invasive optical imaging and sensing. However, spontaneous Brillouin spectroscopy usually requires long integration time, while its spectral quality is fundamentally limited by the optical setups. In this report, we demonstrated that nonlinear Brillouin spectroscopy based on impulsive stimulated Brillouin spectroscopy is capable of providing the necessary acquisition speed and spectral resolution of elasticity measurements. As a proof-of-principle, we demonstrated potential flow-cytometry applications.