An Active Dynamic Vibration Absorber for a Hand-Held Vibro-Elastography Probe

Vibro-elastography is a new medical imaging method that identifies the mechanical properties of tissue by measuring tissue motion in response to a multi-frequency external vibration source. Previous research on vibro-elastography used ultrasound to measure the tissue motion and system identification techniques to identify the tissue properties. This paper describes a hand-held probe with a combined vibration source and ultrasound transducer to implement the new method as a practical device. The device uses a proportional integral active dynamic vibration absorber with an electromagnetic actuator to counterbalance the reaction forces from contact with the tissue. Experiments show an operational frequency range of $5-20Hz$⁠, with at least $15dB$ vibration absorption in $0.4s$ for single frequency excitation. Experiments with variable frequency and amplitude excitation also show a high level of vibration absorption.