Minimally invasive robotic surgery adds benefits to the patients, such as reduced blood loss, less scaring and reduced hospital stay. From the literature research preceding this thesis, some of the major obstacles in robotic surgery are the high costs and limited reusability of the instruments. In order to have more affordable robotic surgery, there is a need for low cost robotics and easily cleanable instruments. The design project presented in this thesis represents a driver interface for robotic control of the SATA instrument and is divided into three detachable subassemblies: a motor unit, a cup interface and a gearbox with angular position feedback. This project also represents an upgrade to an existing design that contains the motors and the gearbox inside a single unit, without any sensorics. Design requirements and goals were establish at the start of the project. Possible solutions were designed in CAD and mapped into a morphological table. Each design obstacle had many possible solutions that were considered before choosing the best suited ones. Two prototypes were build out of aluminium and steel with PEEK bushings and 3D printed outer cases. The range of motion and lateral pulling force of the SATA instrument controlled by these prototypes were tested, together with the assembly-disassembly times and shaft coupling times between the gearbox and motor unit shafts. The experimental results showed very low gearbox exchange times and low coupling times with learning curves that prove the ease of use for new users, all translating into a design that allows fast instrument exchange during surgery. The design requirements were met and physical prototypes built and tested, proving the concept works and is suited for the operating room, heading towards affordable robotic surgery. ... Read more

The upcoming Shaft Actuated Tip Articulated Low Resource Settings (SATA-LRS) platform is in need of a novel design of a strong, foldable beak able to close in parallel. Steerable instruments for minimally invasive surgery (MIS) are used more often but still have some limitations. The end-effectors used are v-shaped, causing tissue that is being clipped to be pushed away or cause peak stresses in the tissue. Many workarounds have been used to avoid these problems, but this project aims to solve the fundamental problem, also taking into account the steerability of the device. V-shaped clips are often limited in size, therefore an expandable u-shaped clip applier is desirable.

AIM: To develop a new type of mechanism able to open and close in parallel in order to apply a u-shaped clip for ligation purposes, which is compatible with the steerable SATA-LRS platform.

METHODS: First, the project definition is chosen, after which the requirements will be formulated and any unknown variables will be experimentally obtained. Then a rigorous morphological analysis will be performed after which the conceptual design is made and the concept selectionis done based on an analytical approach, highly nonlinear FEA-simulations and 5:1 geometrically scaled 3D-printed prototypes to verify the working principles of each of the concepts. The developed concepts will be experimentally validated by means of a test setup.

RESULTS: The designed end-effector allows u-shaped clip with up to 200% increase in size and 400% increase in clip surface area. At a 5mm scale, the expandable beak is able to open just shy of twice the shaft diameter with a span of 9mm, which is close to competing with currently used regular 12mm instruments. The design eliminates limitations currently used v-shapedend-effectors on steerable devices encounter. 50N of clamping force is required, which is three times as much as regular v-shaped gripping. Analytical analysis, FEA simulations and experimental validations show that the device can be made strong enough with a factor of safety of 1.6 and only 0.085mm tip deflection, with an efficiency of 23.1% at a beta angle of 30◦. The device is easily exchangeable on the SATA-LRS platform. A fully functional 5:1 scaled model was successfully made. With minor adjustments to the SATA-LRS, the device can be operated comfortably by any surgeon.

CONCLUSION: This research developed a fully working scaled model of an expandable parallel clip applier, which eliminates the problem regular v-shaped clip appliers have. Also, this system can be mounted to the SATA-LRS and is suitable for steerable instruments. The clips are not limited to the shaft diameter of the device anymore. ... Read more

Over the past decades Minimally Invasive Surgery (MIS) has become a standard in abdominal surgery. Due to limited dexterity and bad ergonomics the field of MIS is shifting towards Robot-Assisted MIS (RAMIS). Simultaneously, the field is using increasingly small and steerable instruments to reduce invasiveness. Surgeon now work with fragile instruments and tissues and are not able to feel the forces they apply. This can lead to unwanted damage to patient and instrument. In an effort to reduce the risk of accidental damage, this work presents a force sensing strategy that is able to measure tip forces in RAMIS using 3mm shaft actuated tip articulated instruments. The system uses a sensorized trocar fixed to the same frame as the instrument to eliminate interfering forces occurring at the trocar. Bending in the instrument due to the applied force at the tip is measured using Hall effect sensors with a silicone transducer. Prototype testing and validation show the proposed sensing system is both accurate and reusable. ... Read more

Laparoscopy involves the use of various instruments for performing different functions. As a consequence, time is spent in exchanging the various instruments, adding to the overall operation time. In order to reduce this overall operation time and solve this problem, the number of instrument exchanges need to be reduced. Reducing the number of instrument changes would also lead to fewer disruptions in the choreography of the surgery and decrease costs related to purchase of instrument and their cleaning. Therefore, in this project, the goal is to develop an instrument with the combined functions of a grasper and a needle holder, to reduce the need of instrument exchanges for performing 2 functions. The requirements for the instrument were decided on the basis of the sub-functions to be performed. Conceptual solutions were then generated to perform the desired sub-functions and systematically compared to obtain a final concept. This final concept was detailed regarding the various mechanisms in the instrument and the distinct assemblies it contains. The force models of these mechanisms were used to theoretically validate the working principles using the required force to be generated. A physical validation of the working principles was also obtained by 3D prints. Further work and research should be done to develop a working prototype of the instrument to validate the functionality of the complete instrument. ... Read more

Minimally Invasive Surgery (MIS) has made tremendous impact on hospitals worldwide. Introduced as a patient friendly alternative to open surgery by significantly reducing incisions size, benefits such as faster patient recovery time, and less pain for patients, are achieved. However, in MIS, rigid instrument shafts can impair surgeons’ dexterity as access to pathology sites is complicated. Steering mechanisms have been developed to locate and orientate an instrument tip for tissue manipulation. Many steerable Minimally Invasive (MI) instruments are intended for single use only, because the actuation cables in those instruments cannot be properly cleaned. Consequently, costly and well-functioning instruments are disposed after each surgical procedure, forming a burden to both hospital sustainability and financial expenses. A platform technology suitable for reuse is brought to the market by the Delft University of Technology in collaboration with Surge-On Medical B.V. Problems with this platform arise in the integration of an internally routed cable, since a hinge in the steering mechanism leads to a critically small cable bending radius. In the present master’s thesis, a bare minimum design approach is followed to make the platform technology compatible with internally routed cables. Based on set requirements, multiple concepts of steering mechanisms are generated and evaluated. The most promising concept is modelled, tested and validated with computer models and experiments. The final design comprises a four-bar linkage mechanism and an innovative joint is used to kinematically stabilize the mechanism. The mechanism achieves 140 degrees of tip articulation and guides internally routed cables with a bending radius of 5mm. The steering mechanism fits through trocars of 5mm and can support loads of 40N, as applied by internally routed cables. The design can be integrated in reusable minimally invasive surgical instruments, since detachment of components allows for effective cleaning and inspection. The designed steering mechanism can be used as building block for reusable minimally invasive instruments, providing an important step to the next generation of steering technology in MIS. ... Read more

The shift from open surgery with one large incision to less invasive techniques with multiple small incisions brings benefits such as less trauma, less scar formation and a faster recovery for the patient. However, in minimally invasive surgery (MIS), surgeons struggle with basic tasks such as applying sutures and tying nots. Clip appliers have been developed to take away the need to apply sutures. From the literature research preceding this thesis and a state-of-the-art investigation, it turned out that current clip appliers do not combine simultaneous steerability and the ability to apply multiple clips. Reaching the surgical site can be difficult or impossible with conventional non-steerable clip appliers, and the reinsertion of a clip applier after every clip application is time consuming and can lead to damage to the instrumentation and patient. The goal of this thesis is to develop a reusable minimally invasive steerable clip applier that can bend clips at the surgical site to close ducts and cuts during laparoscopic procedures. Design requirements and obstacle points are determined for the laparoscopic instrument components by taking the SATA mechanism as a starting point in the design process. Possible solutions to the obstacle points are gathered in a morphological chart that is used to come up with six distinct concepts. A concept choice is made by experimentally finding the required torque to cut and bend a titanium clip and by verifying the ability of concepts to reach this torque by creating a simplified instrument tip on the same scale as the to be designed tip. The worst-case required torque to cut and bend a medium sized titanium clip of 0.5 by 0.8 mm turned out to be 0.6 Nm and 0.03 Nm respectively. During this experimentation it became clear that clips should be supported over the whole length and not just at the ends during the bending process to secure appropriate closing and compression. Several experiments are performed to find a cutting blade attachment that could transmit the worst-case cutting torque while remaining as bendable as possible.
The concept in which the clips are formed in the tip by cutting off a piece of titanium wire and then bent into a clip turned out to be the most promising because it has a theoretically unlimited number of clips at the implantation site without a cartridge, is sterilizable, relatively easy to fabricate due to its simplicity, and can be modified to produce clips with other dimensions. The concept is 3D printed on a 500% scale to verify functionality. This prototype showed that a revision of the actuation mechanism was required and that a few minor alterations could make the instrument easier to sterilize. 3D printing the new design on a 500% scale verified the functionality. The final functional prototype is also 3D printed at a 200% scale, which is the smallest scale that could be achieved with the available resources. The experiments showed that all the required actions could be performed and the prototypes showed that the mechanism functions as required. It is therefore achieved to design a Bend On Site Steerable (BOSS) clip applier that can make and bend clips in the tip from a continuous titanium wire. The instrument is easy to disassemble and sterilize due to the simple design and the small amount of parts. This simple design makes it also possible to make adjustments so that other sizes and shapes of clips can be made. ... Read more