The Demonstration of Additive Manufacture in Power Ultrasonic and Sonar Transducers.

Additive manufacture (AM) has been heralded as a disruptive technology with the potential to revolutionize manufacturing and transform how products are consumed. Within the power ultrasonic and sonar transducer domains, the capability of AM technologies to generate highly complex geometries could facilitate a step change in device performance, yet the usage of metallic additive manufactured parts in power ultrasonic or sonar devices is currently limited. This article demonstrates that it is possible to accurately model, using finite element methods, the vibratory behavior of a power ultrasonic device containing a part fabricated via AM before showing that the vibratory behavior of this device does not significantly vary from an identical device manufactured by conventional methods. Finally, a commercial Tonpilz-like sonar transducer containing a part fabricated by an AM technology is shown to exhibit similar performance to an identical device which contains conventionally manufactured parts.

Ultrasonic Needles for Bone Biopsy.

Bone biopsy is an invasive clinical procedure, where a bone sample is recovered for analysis during the diagnosis of a medical condition. When the architecture of the bone tissue is required to be preserved, a core-needle biopsy is taken. Although this procedure is performed while the patient is under local anaesthesia, the patient can still experience significant discomfort. Additionally, large haematoma can be induced in the soft tissue surrounding the biopsy site due to the large axial and rotational forces, which are applied through the needle to penetrate bone. It is well documented that power ultrasonic surgical devices offer the advantages of low cutting force, high accuracy, and preservation of soft tissues. This paper reports a study of the design, analysis, and test of two novel power ultrasonic needles for bone biopsy that operate using different configurations to penetrate bone. The first utilizes micrometric vibrations generated at the distil tip of a full-wavelength resonant ultrasonic device, while the second utilizes an ultrasonic-sonic approach, where vibrational energy generated by a resonant ultrasonic horn is transferred to a needle via the chaotic motion of a free-mass. It is shown that the dynamic behavior of the devices identified through experimental techniques closely match the behavior calculated through numerical and finite-element analysis methods, demonstrating that they are effective design tools for these devices. Both devices were able to recover trabecular bone from the metaphysis of an ovine femur, and the biopsy samples were found to be comparable to a sample extracted using a conventional biopsy needle. Furthermore, the resonant needle device was also able to extract a cortical bone sample from the central diaphysis, which is the strongest part of the bone, and the biopsy was found to be superior to the sample recovered by a conventional bone biopsy needle.

Analysis of Lead-Free Piezoceramic-Based Power Ultrasonic Transducers for Wire Bonding.

Since the 1950s, lead zirconate-titanate (PZT) has been the dominant transduction material utilized in power ultrasonics, while lead-free piezoceramics have been largely neglected due to their relatively poor piezoelectric and electromechanical properties. However, the implementation of environmental directives that regulate and control the use of hazardous materials, such as lead, triggered a search for new high-performance lead-free piezoceramics. Recent advances have led to lead-free piezoceramics exhibiting properties similar to PZT, but despite this, reports utilizing these novel piezoceramics in practice are limited. This research employs a modified variant of bismuth sodium titanate (BNT) in a power ultrasonic transducer used for metal welding during the manufacture of semiconductors. The important factors for transducer reliability and performance are investigated, such as piezoceramic aging and stack preload level. It is reported that BNT-based transducers exhibit good stability, and can withstand a stack preload level of 90 MPa without depoling. Although the BNT-based transducers exhibited larger dissipative losses compared to identical PZT8-based transducers, the tool displacement gain was larger under constant current conditions. Semiconductor wire bonds which satisfied the commercial quality control requirements were also formed by this BNT-based transducer.

Understanding nonlinear vibration behaviours in high-power ultrasonic surgical devices.

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.

The influence of piezoceramic stack location on nonlinear behavior of Langevin transducers.

Power ultrasonic applications such as cutting, welding, and sonochemistry often use Langevin transducers to generate power ultrasound. Traditionally, it has been proposed that the piezoceramic stack of a Langevin transducer should be located in the nodal plane of the longitudinal mode of vibration, ensuring that the piezoceramic elements are positioned under a uniform stress during transducer operation, maximizing element efficiency and minimizing piezoceramic aging. However, this general design rule is often partially broken during the design phase if features such as a support flange or multiple piezoceramic stacks are incorporated into the transducer architecture. Meanwhile, it has also been well documented in the literature that power ultrasonic devices driven at high excitation levels exhibit nonlinear behaviors similar to those observed in Duffing-type systems, such as resonant frequency shifts, the jump phenomenon, and hysteretic regions. This study investigates three Langevin transducers with different piezoceramic stack locations by characterizing their linear and nonlinear vibrational responses to understand how the stack location influences nonlinear behavior.

In vitro performance testing of two arcuate oscillating saw blades designed for use during tibial plateau leveling osteotomy.

OBJECTIVE: To test the cutting performance of 2 commercially available oscillating saws designed for use during tibial plateau leveling osteotomy (TPLO) and to evaluate the influence of saline irrigation on cutting performance. STUDY DESIGN: In vitro experimental study. SAMPLE POPULATION: Composite polyurethane test blocks (n=40); 24 m TPLO saw blades. METHODS: Controlled force cutting tests were performed using custom-made laminated bone substitute blocks to model the canine proximal tibia. Half of the trials were irrigated with 0.9% saline solution. Outcome measures were test block temperature (measured 1.5 m from the cutting zone), cutting rate, and cutting surface wear. Durability was measured by recording change in performance over multiple consecutive trials. RESULTS: The Synthes blade cut the test blocks with ∼64% less heat generation and at a 63% faster cutting rate compared with the Slocum blade. Although wear of the Synthes blade was ∼50% greater after 19 uses, this did not negatively impact cutting performance. Saline irrigation produced no significant effect on peak cutting temperature but significantly reduced cutting rate for both saws. CONCLUSIONS: Our results favor the Synthes blade in terms of cutting performance and the Slocum blade in terms of wear resistance.