Incorporating direct metal laser sintered complex shaped Ti-6Al-4V components in ultrasonic surgical devices

Abstract

Additive manufacturing (AM) offers opportunities to design more complex shapes of the Ti-6Al-4V parts commonly used in high-power ultrasonic surgical devices. Moreover, AM metal printing will be essential to the realization of miniature ultrasonic devices incorporating internal structures for minimally invasive surgical procedures. However, it is necessary first to verify the ultrasonic vibrational behavior of devices with three-dimensional (3D) printed metal parts. Therefore, two different prototype devices are fabricated, with CNC machined mill annealed and 3D printed Ti-6Al-4V parts. Both devices, an ultrasonic bone needle and a miniature ultrasonic scalpel, incorporate complex geometries but can be manufactured using subtractive processes so that the comparative effects of 3D printing on the vibrational performance of the devices can be elucidated. The metal microstructure is investigated through measurements of longitudinal and shear acoustic velocities and scanning electron microscopy. Comparisons of electrical impedance, frequency and modal responses, and the vibrational response at increasing levels of excitation enable evaluation of the efficacy of incorporating 3D printed Ti-6Al-4V parts. Results show that whereas the bone needle exhibited comparable vibrational responses for the measurement techniques used, the 3D printed bone cutting device exhibited a more dense modal response and developed cracks at high excitation levels.