An OCT-based air jet indentation system for the measurement of mechanical properties of soft tissues

A novel air jet indentation system with the combination of the optical coherence tomography (OCT) technique was presented in this paper for the quantitative measurement of mechanical properties of soft tissues. The key idea of this method is to use a pressure-measured air jet as an indenter to compress the soft tissue and utilize the OCT signals to extract the deformation induced. Experiments were performed on 27 silicon tissue-mimicking phantoms with different stiffness (Youngpsilas moduli, kPa) measured by uniaxial compression test. Regression coefficient of the indentation force to the indentation depth (N/mm) was used as an indicator of the stiffness under air jet indentation. Results showed that the stiffness coefficient measured by the current system well correlated with the Youngpsilas modulus of each phantom (r = 0.89, pLt0.001). Preliminary in-vivo tests also showed that the change of soft tissue stiffness with and without the contraction of the underlying muscles in the hand could be differentiated by the current measurement. This system may have broad applications in the tissue assessment and characterization where alterations of the mechanical properties are involved.