Método ultrassônico de detecção de microvibração: Desenvolvimento da técnica

Abstract

Many investigations have been devoted, during the last years, to implement an ultrasonic method able to generate shear waves and to detect the microvibrations caused by the wave propagation in biological tissues. Applications of such method include measuring rheological parameters for tissue characterization. Considering the potential to use shear wave propagation, this work presents an ultrasonic method able to detect microvibrations (UDmV), which is based on Kalman filtering to estimate the medium vibrations from a signal contaminated with noise. The UDmV was tested employing a speaker to generate microvibrations on a membrane and a pulse-echo ultrasonic system, operating at a center frequency of 4.96 MHz, to detect the membrane microvibrations. The UDmV demonstrated promising future potential, being able to detect the vibration frequency and amplitude with the same order of magnitude as presented in the literature (≈10 mm). Moreover, the method implemented in the present work confirmed previous results, from the literature, related with a reduction of the estimated vibration amplitude as the vibration frequency increases. The method developed in the present work can be employed to estimate the phase velocity and the attenuation coefficient of a shear wave propagating in a viscoelastic medium.