Journal of biomedical optics
Multikilohertz optical microelastography for viscoelastic characterization of soft biomaterials demonstrated on melanoma spheroids
By Cortés JM, Faris IH, Hurtado M and 4 others.
Abstract
Significance
The stiffness and viscosity of biological tissue determine how mechanical forces are transmitted and dissipated within it, and both are increasingly used to study tumor growth and treatment response. Measuring these properties within small three-dimensional samples is challenging: it requires shear waves at kilohertz frequencies, which attenuate over short distances, while conventional excitation methods introduce additional signal loss that is difficult to separate from the intrinsic dissipation of the tissue.
Aim
To enable sub-millimeter viscoelastic characterization of three-dimensional biological constructs in the multikilohertz frequency range using quasi-planar wave excitation and optical detection. Approach: We developed an optical microelastography platform that combines quasi-planar shear-wave excitation using a piezoelectric actuator, high-speed imaging (up to 210,000 fps), and k -space dispersion analysis to estimate frequency-dependent viscoelastic parameters through a Kelvin-Voigt model. The system was validated using polyacrylamide phantoms with tunable viscoelastic properties at five concentrations (15% to 26% v/v).