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Session: Poster Session 1 (Even numbers)
Session starts: Thursday 26 January, 16:00
Presentation starts: 16:00

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Jan-Willem Klok (Technische Universiteit Delft)

Abstract:
Introduction In laparoscopy, surgeons occasionally find it difficult to perceive forces exerted to the tissue, as well as to assess tissue characteristics through haptic feedback. This is due to poor transmission of surgeons’ instrument control forces, caused by friction and play in the grasper joints. These factors negatively impact instrument haptic feedback and can cause excessive tissue damage. Therefore, a laparoscopic grasper overcoming these problems has been designed. Methods This laparoscopic grasper features a novel compliant grasper tip type. In contrast to conventional laparoscopic graspers, this compliant grasper tip does not have joints that can cause play or friction. Instead, it utilizes elastic elements facilitating the opening and closing movement of the jaws. The instrument’s sensitivity was validated by measuring the level at which participants could discriminate force differences applied at the grasper tip with an increasing force level, while the subjects were holding the new instrument and a conventional grasper at the handle grip. The force was increased and subjects reported at which force level they were able to feel an increase. Also, mechanical efficiency of both graspers was measured. Results There was a significant difference in sensitivity between the instruments (p<<0.05) in favor for the compliant grasper (mean 1.4N SD0.44N) compared to the conventional grasper (mean 2.7N SD1.2N). The mechanical efficiency of the new instrument and conventional grasper is 43% and 25%, respectively. Discussion and conclusion The results show that the compliant laparoscopic grasper has a higher force sensitivity and a higher mechanical efficiency than a conventional grasper, enabling to perceive lower tip forces. This has significant benefits, potentially lowering the threshold of tissue forces that a surgeon can perceive, improving the perception of grasper tip-tissue interaction. The instrument can help surgeons to discern healthy and cancerous tissue by perceiving stiffness. Based on these findings, a new prototype was built. It features an improved compliant tip with reduced actuation forces. Furthermore, instrument weight has been reduced. Currently, a new validation study on the haptic feedback is being developed, aiming to investigate the distinction between ‘self-generated’ haptic feedback from palpation, and ‘tissue-generated’ feedback from pulsating blood vessels.