Understanding nonlinear vibration behaviours in high-power ultrasonic surgical devices

Abstract

Ultrasonic surgical devices are increasingly used in oral, craniofacial and maxillofacial surgery to cut mineralized tissue, offering the surgeon high accuracy with minimal risk to nerve and vessel tissue. Power ultrasonic devices operate in resonance, requiring their length to be a half-wavelength or multiple-half-wavelength. For bone surgery, devices based on a half-wavelength have seen considerable success, but longer multiple-half-wavelength endoscopic devices have recently been proposed to widen the range of surgeries. To provide context for these developments, some examples of surgical procedures and the associated designs of ultrasonic cutting tips are presented. However, multiple-half-wavelength components, typical of endoscopic devices, have greater potential to exhibit nonlinear dynamic behaviours that have a highly detrimental effect on device performance. Through experimental characterization of the dynamic behaviour of endoscopic devices, it is demonstrated how geometrical features influence nonlinear dynamic responses. Period doubling, a known route to chaotic behaviour, is shown to be significantly influenced by the cutting tip shape, whereas the cutting tip has only a limited effect on Duffing-like responses, particularly the shape of the hysteresis curve, which is important for device stability. These findings underpin design, aiming to pave the way for a new generation of ultrasonic endoscopic surgical devices.

Dynamic Nonlinearity in Piezoelectric Flexural Ultrasonic Transducers

“…Documented phenomena include reductions in transducer amplitude, instability, and a drift of resonance frequency [15]- [17]. There are several scientific studies into the nonlinearity in the vibration response of ultrasonic devices, including high-power transducers [15]- [18]. The dynamic nonlinearity associated with the vibration of discs and plates, including piezoelectric elements, has also received significant attention in the scientific literature [19]- [22], but there is little detailed analysis of the nonlinearity associated with flexural ultrasonic transducers, those which generate ultrasonic waves through bending motion.…”

Venting in the Comparative Study of Flexural Ultrasonic Transducers to Improve Resilience at Elevated Environmental Pressure Levels

“…For most ultrasonic measurements, the transducers' resonance frequencies should be suitably matched and ideally experience minimal variation in response to changes in environmental conditions. Shifts in resonance frequency have been known to arise due to nonlinear dynamic phenomena [8,[19][20][21][22][23], but there are other explanations for the distinctive reduction in the CFUT's resonance frequency in these experiments. As is increased, there will be a direct influence on the boundary condition of each transducer.…”

Ultrasonic Needles for Bone Biopsy

“…The resonant frequencies and modes of vibration of the USR needles and of the transducer-horn assembly of the USS needle were modeled using the finite-element analysis (FEA) software, Abaqus (Dassault Systèmes). The FEA predictions were validated using experimental modal analysis (EMA), which has been described previously [19]. To ensure that the ultrasonic transducer-horn assemblies were driven at a constant vibration amplitude and at resonance, LabVIEW software (National Instruments) was used to coordinate a resonance tracking protocol [20].…”

“…2) Device Tuning and Modal Identification: It is known that slender multiple half-wavelength power ultrasonic devices can exhibit undesirable vibrational behaviors, such as modal coupling, which can detrimentally affect their performance and reliability [19]. To minimize the likelihood of such behaviors, the USR needles were tuned to maximize the modal frequency separation between the second longitudinal mode of vibration and neighboring modes of vibration.…”