No abstract

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 ® .

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 was calculated for both 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 d31 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.