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High-Q PIC 181 hard piezoceramic and high-k Mn:PIN-PMN-PT piezocrystal thickness extensional rings have been compared for use in the actuation of an ultrasonic scalpel for robotic endo-surgery. Measured material properties have been verified with both finite element analysis and laser vibrometry, to assess the materials' suitability for high power devices. Measured material properties have been verified with both finite element analysis and laser vibrometry, to assess material's suitability for high power devices. Measurements have shown a kt = 0.25 and Qm = 2200, and kt = 0.62 and Qm = 1100, for PIC 181 and Mn:PIN-PMN-PT respectively. Conventional bolted Langevinstyle transducers (BLTs) have been successfully designed and built to resonate at 20 kHz for both piezomaterials. Modal parameters and performance have been modelled in FEA and measured via laser doppler vibrometry. When devices were excited with 50 Vrms at L1 a displacement of 8 µm and 7 µm was measured for PIC-181 and Mn:PIN-PMN-PT BLTs respectively. Results suggest that a similar resonant frequency can be achieved with a shorter and equally functional device excited by Mn:PIN-PMN-PT piezocrystals.

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The Harmonic ACE ® (J&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 ® .

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