Abstract
This paper describes online measurement of time-varying viscoelasticity of subcutaneous by external stimulation. Time-varying dynamic stiffness in subcutaneous tissues may be estimated by using the self-excited vibration generated by the positive feedback of velocity. Then we showed that viscoelastic coefficient in subcutaneous tissues, which didn't depend on measurement conditions, could be quantified with the estimated dynamic stiffness, based on the Hertz's formula and the correspondence principle between the theory of elasticity and viscoelasticity. In case that the skin is sprayed with lotion as external stimulation, it is shown that time-varying viscoelasticity of subcutaneous tissue is measured on line.
