Towards Ultrasonic Scalpel for Single-Port Robotic Surgery: Design of a Miniature Langevin Ultrasonic Transducer

The manipulation difficulties in laparoscopic procedures inspire the development of surgical robotic systems. To perform tissue dissection and coagulation, electrosurgical instruments and ultrasonic scalpels are integrated. Ultrasonic scalpels, which utilize high-frequency vibration generated by ultrasonic transducer to dissect and coagulate tissues, are safer than electrosurgical instruments due to concentrated energy release. However, the rigid straight waveguides involved in conventional ultrasonic scalpels prevent their integration into single-port surgical robots, within which multi-joint articulated or continuum bendable instruments are used. Putting miniature transducers at the distal end of the instruments is a potential way to integrate ultrasonic scalpels. However, the existing miniature ultrasonic transducers arranged at instrument distal ends have limited energy efficiency due to their 55.5-kHz half-wavelength design. This paper hence proposes the design of a 6-mm 120-kHz full-wavelength miniature ultrasonic transducer. The proposed 120-kHz full-wavelength structure can provide sufficient energy efficiency while maintaining the transducer’s compact size. Finite-element model is utilized to optimize the proposed transducer’s structure. The tissue dissection capability of the proposed 120-kHz miniature ultrasonic scalpel is demonstrated experimentally. It’s promising for the proposed design to be integrated into an 8 mm continuum instrument for single-port robotic surgery.