Novel Smart Actuation Systems for Single-port Laparoscopic Surgical Instruments

  • Haochen Wang

    Student thesis: Doctoral ThesisDoctor of Philosophy


    Single-port Laparoscopic surgery (SLS), which utilises one major incision instead of multiple incisions, has gained increasing popularity in the healthcare system in recent years. Compared with the conventional multiport laparoscopic surgery, SLS technique can deliver favourable cosmetic outcomes with less hospitalisation stay and postoperative pain for the patients. However, SLS procedures have been suffering from several drawbacks, which are due mainly to the fact that only one trocar port is available to accommodate all the surgical instruments and therefore, it is difficult to achieve the required angulation during these procedures. This problem was worsened by the limited functionality of the current surgical instruments, which are rigid and slender, resulting in their inability to provide the optimum articulation required to complete certain SLS tasks.

    This project is aimed to develop lightweight, compact and smart actuation systems which could be applied to enhance the functionality of SLS surgical instruments by increasing their articulation ability, robustness and stability. In particular, the new actuation systems are proposed to be embedded at selected joints along the stems of current SLS instruments to enable them with adaptability in changing their levels of stiffness and degrees-of-freedom without compromising patient safety.

    The project started with a review of the requirements for actuation systems that could be applied to improve the function of SLS instruments. Various actuation techniques were then considered and only those which satisfied the design criteria were taken forward and thoroughly investigated. Accordingly, three smart actuation systems were then developed, which are namely a latching-type electromagnetic actuator, a soft dielectric elastomer spring roll actuator and a novel hydraulic actuation system. Advanced theoretical and numerical design and assessment techniques were utilised in the development of these smart actuation systems and prototypes were manufactured using 3-D CNC machining and prototyping printers. In addition, dedicated experimental arrangements were set up to determine the performance of the developed actuation systems, which were checked against stringent SLS requirements such as articulation, strength and safety.

    Although, all of the developed actuation systems were found to enhance the function of the current SLS instruments, it was concluded that the actuation system with the latching-type electromagnetic actuators could offer the best performance improvement for these instruments. The latching-type electromagnetic actuator was designed with two different mechanisms to transfer the linear motion of the actuator into an angulation. One of these mechanisms involves a ball and socket components, which was capable to deliver an angulation of about 30°. In order to allow a multi-degrees-of-freedom capability into the operation of an SLS instrument, about three of the developed latching-type electromagnetic actuators were proposed to be embedded in tandem along the stem of the instrument. In contrast, a hybrid gear and tendon-driven mechanism, which is equipped with about three of the developed latching-type electromagnetic actuators and aided by an additional manual control needed for the completion of the actuator’s motion, was also developed and was found to provide the SLS instrument with angulations ranging from -90° to 90°. In addition, the torque provided by the former system was found to be about 34mN.m (from each joint) whilst the latter system could enable a much larger torque output. Considering the torque capability of the two configurations of the electromagnetic actuation system, the ball and socket design was assumed to be suitable for the angulation of an SLS camera or endoscope which do not bear much load during SLS operations while the hybrid gear and tendon-driven mechanism was deemed to be more suitable for the articulation of other SLS instruments, such as graspers and scissors.

    The flexibility and functionality of SLS instruments would certainly be improved with the addition of the developed smart actuation systems and consequently, safer and more efficient SLS procedures could be performed by the surgeons. In future work, it is proposed that the prototypes of the developed actuation systems are subjected to systematic clinical trials in order to practically verify the reliability of such systems using dummy and cadaver settings.
    Date of Award2019
    Original languageEnglish
    SponsorsWellcome Trust
    SupervisorAli El-Wahed (Supervisor)

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