Design of a tissue resonator indenter device for measurement of soft tissue viscoelastic properties

The design of a new device called tissue resonator indenter device (TRID) for measuring soft tissue viscoelastic properties is presented. The two degrees-of-freedom device works based on mechanical vibration principles. When TRID comes into contact with a soft tissue, it identifies the tissue's viscoelastic properties through the change of its natural frequencies and damping ratios. By working in the linear viscoelastic domain, TRID is designed to identify tissue properties in the range of 0-100 Hz. Assuming Kelvin tissue model, a method is developed for determining unknown tissue parameters using input-output data from TRID. A parametric identification method using the prediction error approach is proposed for identifying the unknown tissue parameters, which is proved to be globally identifiable, in a grey-box state-space model. The effectiveness of the identification method is demonstrated using simulation in the presence of considerable input and output noises.