Effect of longitudinal-bending elliptical ultrasonic vibration assistance on electrosurgical cutting and hemostasis

Electrosurgical devices are widely used for tissue cutting and hemostasis in minimally invasive surgery (MIS) for their high precision and low trauma. However, tissue adhesion and the resulting thermal injury can cause infection and impede the wound-healing process. This paper proposes a longitudinal-bending elliptical ultrasonic vibration-assisted (EUV-A) electrosurgical cutting system that incorporates an ultrasonic vibration in the direction of the cut by introducing an elliptical motion of the surgical tip. Compared with a solely longitudinal ultrasonic vibration-assisted (UV-A) electrosurgical device, the EUV-A electrode contacts the tissue intermittently, thus allowing for a cooler cut and preventing tissue accumulation. The experimental results reveal that the EUV-A electrode demonstrates better performance than the UV-A electrode for both anti-adhesion and thermal injury through in vitro experiments in porcine samples. The tissue removal mechanism of EUV-A electrosurgical cutting is modeled to investigate its anti-adhesion effect. In addition, lower adhesion, lower temperature, and faster cutting are demonstrated through in vivo experiments in rabbit samples. Results show that the EUV-A electrode causes lower thermal injury, indicative of faster postoperative healing. Finally, efficacy of the hemostatic effect of the EUV-A electrode is demonstrated in vivo for vessels up to 3.5 mm (equivalent to that of electrocautery). The study reveals that the EUV-A electrosurgical cutting system can achieve safe tissue incision and hemostasis.