Sol-gel transition in agar-gelatin mixtures studied with transient elastography

Abstract—Using the shear wave propagation in solids, the transient elastography technique has been developed to assess the elastic properties of soft tissues. Here, a new approach of transient elastography allows assessing the viscoelastic properties of soft tissues. In this paper, the method is used to follow-up the sol-gel transition of an agar-gelatin mixture noninvasively. The shear wave velocity and shear wave attenuation through the mixture were continu-ously monitored in the audible range of frequencies (from 50 Hz to 200 Hz). The observed changes in velocities and attenuations as a function of frequency confirmed the va-lidity of the Voigt’s model to describe the gel at its stable mechanical state. By a simple inverse problem approach, based on the one-dimensional (1-D) Helmholtz equation, the elasticity and the viscosity of such a mixture were re-covered as a function of time. The results obtained are in good agreement with the literature and theoretical predic-tions. Overall, they demonstrate the high sensitivity of the transient elastography measurements to the rheological pa-rameter changes in agar-gelatin mixtures during gelation. I