5 research outputs found

    Comparing generation III relaxor-PT single crystal with modified PZT-4 for power ultrasonics devices

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    Lead-based piezocrystals have been thoroughly investigated by various research teams for power ultrasonic transducers. The key objective of this work is to evaluate whether Gen. III single crystal could provide similar performance to the Navy type I (similar properties to PZT-4) and help in miniaturising the overall length of power ultrasonic instruments. This study started by incorporating four different material rings, Pz24, Pz26, and PIC181, as modified PZT-4, and Mn: PIN-PMN-PT (Gen. III single crystal) in cylindrical bolted Langevin transducers (BLTs) and comparing their key performance with respect to mechanical quality factor, electromechanical coupling coefficient, non-linearity, vibration response and nodal plane location. For the same operating frequency for all BLTs, the Gen. III single crystal transducer was found to be the shortest in length by 8~11 mm (7.6 ~ 10.4%). When testing the vibrational amplitude, the Gen. III single crystal has the highest tip normal-to-surface amplitude with lower current compared to other transducers. Gen. III was found to not follow the same non-linear behaviours as the piezoceramics transducer. Thus, the Gen. III transducer undergoes a change of material properties and depolarisation when excited with high voltage

    Progress Towards the Miniaturization of an Ultrasonic Scalpel for Robotic Endoscopic Surgery Using Mn:PIN-PMN-PT High Performance Piezocrystals

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    Mn:PIN-PMN-PT piezocrystals are under consideration for potential use in miniaturised ultrasonic scalpels for robotic minimally-invasive surgery where small size and light weight may be advantageous. Electromechanical coupling coefficient k > 0.9 for both [001] and [011] poled Mn:PIN-PMN-PT was calculated, confirming the well-recognized higher efficiency of this material when compared to standard piezoceramics. Novel transducer design strategies have been explored, and outcomes are discussed. The introduction of components with additional compliance in a standard d 31 mode transducer has been shown to drop the resonant frequency of the first longitudinal mode by more than 17%, with more than 75% improvement in tip/blade displacement. Results suggest that the combination of high performance piezocrystals with highly compliant components may be a useful route to follow to achieve our miniaturisation target

    Miniaturisation and optimisation of ultrasonic scalpels for robotic surgery

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    Incorporating Planar Folded Front Masses in Bolted Langevin-Style Transducers for Minimally Invasive Surgery

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    The Harmonic ACE® (J and J Medical Devices, OH, USA) based on the conventional Bolted-Langevin Transducer (BLT) configuration of piezoelectric transducers is used in robotic surgery due to its fast cutting of soft tissues and improved cut quality. However, the manoeuvrability of the Harmonic Ace® which is the only ultrasonic scalpel compatible with the Da Vinci Surgical System® (Intuitive Surgical Inc., CA, USA) is very limited for the surgeon, due to its long shaft and tool-robot configuration. Till now, there is no existing ultrasonic scalpel compatible with the Da Vinci® Surgical System EndoWrist® instruments. Therefore, the key objective of this work is to create miniaturised ultrasonic instruments to allow greater dexterity than conventional tools. To address this, an alternative approach can be adopted which utilises a planar folded front mass incorporated within BLT configurations with the aim to reduce the overall length of the tool whilst maintaining the amplification gain. The introduction of planar folded (PF) and twice planar folded (TPF) front masses within BLT configurations and after being optimised using design of experiments (DOE) techniques, demonstrate high amplification gains, GA = 90 @ 23 kHz and GA = 92 @ 21 kHz, respectively, and transducer lengths of 58 mm (87% length reduction) and 64 mm (86% length reduction) compared with a 450 mm Harmonic ACE®

    Flexural Ultrasonic Transducers with Nonmetallic Membranes

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    The flexural ultrasonic transducer is a sensor primarily composed of a circular metallic membrane, to which a piezoelectric ceramic disc is bonded. The vibrations generated from the piezoelectric ceramic stimulate plate modes in the membrane, thereby generating ultrasound waves. FUTs are typically utilized for industrial and proximity measurement, but there has been growing research activity in recent years focusing on alternative applications, such as those requiring elevated pressure and temperature. The membrane of the FUT remains limited to circular metallic configurations, but there are opportunities for more complex and targeted ultrasound responses if the physical properties and shape of the membrane can be manipulated. These can include focused ultrasound beams, enhanced bandwidth, and the generation of higher order modes at desirable frequencies for measurement. The aim of this study is to investigate the viability of using nonmetallic materials such as acrylics, including through 3D printing, to tailor membrane design, and thus FUT dynamics
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