The effect of driving conditions on the performance of an ultrasonic bone biopsy needle

Ultrasonic surgical devices are currently used in various soft and hard tissue surgeries. This study focuses on investigating how modifications of the device driving signal can affect the needle penetration speed. The penetration speed, and therefore time for extraction of a biopsy, should be comparable with a conventional trephine biopsy needle. The ultrasonic bone biopsy device was designed using finite element analysis (FEA) and tuned to operate in a longitudinal mode at 25 kHz. The device was manufactured and experimental modal analysis (EMA) was used to validate the FEA model and measure the modal parameters. A series of tests were carried out, based on the time to perform a 5mm penetration of the needle into a polyurethane foam which acts as a substitute trabecular bone material. During each penetration the temperature and time were recorded. Following this, the study focused on investigating power modulation techniques, as have been widely adopted for phacoemulsification where power modulation in c...