Endoscopy is an essential medical procedure that is used to diagnose a large variety of conditions. Endoscopes are traditionally manually inserted by an operator and during this process the mechanical movements of the endoscope may cause complications. Self-propelling endoscope designs have been proposed which pull themselves through a lumen. This may reduce trauma and operator skill required in comparison to traditional endoscope designs. This study proposes a novel locomotion mechanism for use in self-propelling endoscopes and seeks to assess its feasibility.

A robot was built which may locomote using in an inchworm-like manner using ultrasonic friction modulation. It was then tested on tracks designed to model the conditions in which an endoscope operates. It's performance and robustness of motion was then measured and evaluated for use in endoscopy.

The robot locomoted at a maximum speed of 15.6mm/s when actuated inside a PLA track, achieving faster performance than other self-propelling endoscope designs. However, it was prone to perturbations and was unable to traverse an elastic substrate or a track modeling a human airway. These findings validated that inchworm-like locomotion using friction modulation is feasible and that it currently presents some potential benefits in endoscopy. Further work is required to assess the performance of this locomotion mechanism over natural tissues and to improve its resistance to perturbations.

The removal of tissues from the human body is a fundamental aspect of surgical interventions, especially in Minimally Invasive Surgery (MIS). In MIS, one or multiple small incisions (approximately 3 to 10 mm) are made, and the body is accessed by long slender devices. MIS offers benefits such as less postoperative pain, and shorter hospital stays, driving a trend toward miniaturisation: smaller medical instruments. Current suction-based instruments are limited in performance by clogging, shaft miniaturisation challenges, and dependency on tissue composition. To address these limitations, alternative mechanisms for transportation have arisen such as friction-based transportation. This study presents the design and experimental validation of a flexible friction-based tissue transporting device for MIS. The device is designed to achieve transportation efficiency independent of tissue elasticity within a Young's modulus range of 1-110 kPa, utilising a cylindrical conveyor mechanism with wires to transport tissue. Experimental validation demonstrated consistent transportation efficiency (75%) across various tissue types, shapes, and orientations, though shaft curvature significantly affected performance and total reliability (81%). The device addresses some of the limitations of suction-based instruments, including reduced clogging, enhanced potential for miniaturisation, and transportation efficiency independent of tissue elasticity. While further improvements to the device design are necessary, it has the potential to improve MIS tissue removal procedures and patient outcomes.

Minimally invasive medical procedures often require catheters, endoscopes and other devices to maintain position at a specific site in the body, to cut and remove tissue or for diagnostic purposes. Due to tool force exerted by the surgeon or the natural processes of the body, such as the activity of the heart or the lungs, the inserted device can dislodge or migrate from its intended location. Existing solution focus on stabilizing the tip, following high localized pressure, this can create tissue damage or even perforation. Hence, it can be beneficial to create stabilization over the full length of the catheter. I investigated the use of electroadhesion i.e. using electricity to adhere to the tissue wall. I created a scaled-up, flexible, electroadhesion stabilization proof of concept, consisting of two opposite-charged electrodes in a helical pattern, embedded in silicone rubber. Friction experiments were performed on the catheter proof of concept on two copper half-tube substrates. One of the three flexible scaled-up catheter samples showed an increase in the average dynamic friction coefficient of 10.2% between 0 and 2500 V for the 22 mm diameter substrate. The two other samples showed no or limited increase in friction, attributable to manufacturing differences. Predicting coating thickness is essential, as the coating is the determining factor for the performance of the electroadhesion device. The catheter showed potential, however, improved adhesion performance is required for feasibility on a smaller scale.

Sliding robotic devices are often employed in sensitive applications, such as medical procedures. These devices rely on frictional interaction with their environment to generate locomotion, which can be significantly enhanced through active friction modulation. In this study, we propose a friction modulating slider that uses ultrasonic vibrations to achieve squeeze film levitation for friction control. This paper describes the design and evaluation of a friction-modulating slider for generating efficient locomotion in a two-slider prototype. The slider’s ability to modulate friction was tested through friction force experiments on a variety of surfaces, and its feasibility for locomotion was tested. The results show that the slider effectively reduced friction across different surfaces and enabled locomotion in the two-slider system. These findings highlight the potential of friction-modulating sliders to enhance the locomotion efficiency of sliding robotic devices, offering promising opportunities for various applications.

Tissue extraction in Minimally Invasive Surgery is often performed using a suction catheter, valued for its capability to continuously remove tissue from the body. However, suction catheters face limitations in further miniaturization and reliability due to energy losses and clogging. Kortman et al. (Kortman, 2023) proposed a solution: a soft tissue transporter that does not affect the surrounding tissue and enables miniaturization without sacrificing performance. The mechanism involves a soft silicone-based conveying toroid that transports tissue from one end of the tube to the other end of the tube. However, a shortcoming of the device is its inability to function as a continuous tissue transporter. Continuous transporters are often preferred as they shorten surgery times, reduce the amount of anesthesia needed and lower the overall operational costs compared to discrete transport mechanisms. Therefore, the goal of this study is to develop a continuous toroid tissue transporter, compatible with Minimal Invasive Surgery, for which the transport efficiency is independent of the tissue elasticity, shape and size. The final concept featured a toroid that was continuously everted while remaining stationary, enabling it to function as a conveyor-like mechanism. By integrating an internal skeleton with magnets at its edges, the toroid could be actuated externally using a gearbox. Additionally, an uniaxial mesh was incorporated into the toroid to allow flexibility in its width, allowing the shape grip to transport various objects, while preventing stretch in the length of the toroid, thereby improving eversion efficiency. A proof-of-principle prototype was developed to validate the working principle. Results demonstrated that the toroid efficiency was not limited by various tissue sizes, shapes or elasticities. Therefore, the study goal has predominantly been achieved.

Improvement of actuation efficiency can be achieved by further alignment between the actuation system and the toroid, as currently slip is causing a reduction in actuation efficiency. In conclusion, the Continuous Toroid Transporter demonstrates promise for surgical applications and other fields requiring precise object transportation and is recommended to be further developed.

This thesis explores the fabrication of biomimetic shark skin, focusing on actively controlling the bristling effect of denticles, inspired by the passive bristling effect observed in the skin of Shortfin Mako sharks. By examining the natural structure and functionality of shark skin, the research aims to replicate its unique properties using innovative fabrication techniques. A review of previous methods for replicating shark skin structures led to the selection of an indirect fabrication approach, driven by the necessity to integrate an actuation mechanism. Drawing inspiration from soft robotics, the study identified Nitinol, a shape memory alloy, as the optimal material for actuation due to its significant force exertion and seamless integration into the silicone shark skin.
Experiments were conducted in a water tank, testing various configurations of biomimetic shark skin to evaluate the performance of the integrated actuation mechanism. The initial findings demonstrated that Nitinol wire actuation within a silicone matrix effectively mimics the bristling mechanism, even in aquatic environments, showing sufficient strength to counteract water flow. While this research successfully demonstrated the feasibility of integrating actuation mechanisms into biomimetic shark skin, further studies are necessary to optimize the design for practical applications.

TransPerineal Laser Ablation (TPLA) is a novel, minimally invasive procedure that uses accurately positioned needles through which optical fibres are inserted to ablate malignant prostate tissue, demonstrating minimal side effects in early studies. Accurate needle placement and guidance can be affected by many factors such as needle buckling, imaging modality, and needle deflection. Using the self-propelling mechanism seen in the ovipositor of parasitoid wasps, the risk of buckling can be reduced and tissue damage can be minimised. Drawing inspiration from this principle, we created a stationary, MR-conditional 3D printed device with integrated laser functionality that can propel a needle system through stationary, human-like tissue. Our results show that needle traversal through multiple gelatin phantoms (up to 15 wt%) is possible. The needle (bundle) can move through these phantoms without buckling, due to its near-zero (max 0.28 N) net put force. The propelled needle (bundle) has an outer diameter of 1.2 mm, which includes a centrally located needle through which the optical fibre, used for laser ablation, can be inserted. Our wasp-inspired needle design and prototype narrow the gap to the clinical implementation of wasp-inspired needles for MRI-guided TPLA. Moreover, with minimal design changes, our device may serve as a versatile platform for applications beyond its intended purpose of TPLA, such as camera positioning, drug delivery, tissue engineering, and tissue extraction.

The spine serves as our literal backbone, providing support and facilitating movement, but spinal issues can greatly impact daily life. Spinal fusion surgery addresses severe problems by fusing adjacent vertebrae using pedicle screws and rods. However, traditional fixation methods like these encounter challenges such as screw loosening, particularly in weaker bone. This thesis presents an exploratory study delving into alternative bone anchor designs to enhance the fixation strength. Additionally, this thesis explores the use of steerable bone drills to enable alternative anchor trajectories, aiming to further enhance the fixation. This thesis also examines additional functionalities, such as tissue removal, to improve medical procedures. Through these investigations, the thesis aims to advance spinal fusion surgery techniques, ultimately enhancing patient outcomes and quality of life.@en

Additive manufacturing, or 3D printing, offers a new paradigm for the way functional products are designed, manufactured, and assembled. Its additive nature provides the ability to create complex-shaped parts, without an increase in production time or costs, which would be difficult to produce with conventional manufacturing. In addition, integration of different functions and materials allows for the production of completely functional assemblies or mechanisms that can be produced in a single production step, known as non-assembly additive manufacturing. These mechanisms are functional immediately after 3D printing, without requiring additional assembly steps. Non-assembly mechanisms have some advantages over traditional assembly-based mechanisms, as they reduce the processing time and costs, and allow for an increase in complexity....@en

Background:
An endomyocardial biopsy (EMB) is an invasive procedure where biopsy samples are taken from within the heart for diagnosis of different myocardiopathies and or heart transplant rejection monitoring. During EMB procedures, a minimum of five tissue samples are required to be taken from the heart wall for investigation.
Current bioptomes are not able to retrieve more than one sample at a time and therefore need to be re-inserted at least four times. This can lead to complications such as air embolisms. The goal of this design study was to develop a novel cardiac bioptome for endomyocardial biopsies that can take and store multiple biopsy samples during a single insertion.

Design:
The bioptome developed in this study had two major functionalities, resection of myocardial tissue and storage of multiple tissues. Each functionality could be divided into multiple sub-functionalities. From these functionalities the design requirements followed. Afterwards, the alternatives for each subfunctionality
were explored. For the tissue resection, different possibilities for the method of resection, position of the resection tool, direction of resection forces, and motion of resection, were explored. For tissue storage, different possibilities for the storage system, tissue transportation, and sample loss prevention were explored. Following this exploration, multiple design concepts were devised. Two of these concepts, the ’corer’ concept and ’ovipositor’ concept were developed further. These two concept were compared and the ’corer’ concept was chosen as the most viable option. Prototypes of this concept were developed and tested for the functioning of its working principle for tissue resection and storage and for the functioning of the actuation mechanism.

Results:
The experiments showed that the end-effector of the bioptome works as expected and that thus the working principle of the ’corer’ concept for resection and storage of biopsy samples functions as intended. The experiments also validated the functioning of the actuation mechanism within the handle. The experiments however also showed that the flexible shaft was unable to correctly transfer the motion from the actuation mechanism in the handle to the end-effector.

Discussion & conclusion:
More suitable materials are required for future prototypes to improve motion transfer. Furthermore, a steerability functionality should be added to the design to make the bioptome fully functional for EMB procedures. The final design should be tested in an environment more closely resembling the clinical scenario. If these tests are successful, it can be concluded that the bioptome can indeed improve endomyocardial biopsy procedures.

Artificial Muscles (AMs) are often used as the actuation source for soft robots. AMs demonstrate great power-to-weight ratios, are generally compliant and therefore a safe mode of actuation in human-machine interfaces. Flat Pneumatic Artificial Muscles (FPAMs) are a subgroup of AMs and are designed to contract once pressurized. They are low-volume silicone bladders that An analysis of the current research on FPAMs provides knowledge about the benefits and improvements that can be made. The design of a novel FPAM is presented to reduce the normal expansion during actuation. The novelty that this paper brings includes: 1) a new production method with embedded mesh as the reinforcement of the silicone bladder 2) intricate zero-volume air chamber (ZAC) designs formed by dissolving 3D-printed Polyvinyl alcohol (PVA) masks 3) normal expansion measurements aimed to find the relation between internal pressure, air chamber design and normal expansion of the novel FPAM. Three different ZAC designs will be examined: a rectangular, a hexagonal and a diamond pattern. They are characterized with isometric contraction - and active force control tests at 60 kPa. During these tests the normal expansion of the FPAMs will be measured with a laser sensor. The rectangular ZAC design proved to outperform the other patterns by a wide margin. It produces 200\% more isometric force (13.3 N) and 400\% more contraction (7.7 mm / 9.7\%). However, the diamond ZAC showed a reduced normal expansion of 54 \%, thereby achieving the goal of reducing the normal expansion by redesigning the ZAC.

Suction grippers have the advantage to handle many different types and sizes of items, without being restricted by the dimensions of clamps to enclose an object and to handle objects more delicately.
However, the challenge of attaching these grippers to irregularly-shaped and rough surfaces remains a persistent issue. Despite advancements in research, the possibilities for miniaturisation, specific control, speed, and universal gripping capabilities still pose significant challenges. This study aims to overcome these obstacles by embedding magnetic intelligence within the material of a suction gripper and enabling the actuation of the attachment by an external magnetic field.
In this study, magnetic responsive soft materials are explored and different suction mechanisms are designed and validated to explore the opportunities of a magnetically actuated suction gripper. The miniaturisation options of the gripper are improved by implementing a compliant deploying mechanism. This results in the design of a magnetic actuated deployable suction gripper, using a thin magnetic membrane consisting of carbonyl iron particles in a silicone matrix material, in a frame of superelastic nitinol providing pressure on the rim and allowing for deploying.
A proof-of-principle prototype has been experimentally validated for attachment performance on a variety of curved surfaces in both dry and wet environments.
The attachment was achieved on curved surfaces with a radius of 50mm and 75mm, with a maximum attachment force of 2.89 \textpm 0.54 N. Observation suggests that only on surfaces with a curvature that is positioned exactly at the rim of the gripper attachment is not possible. For these surfaces, the nitinol wire rim prevented the flexible footprint membrane to seal onto the surface and leakage occurred.
The current gripper design is able to achieve a 75\% folding percentage, which allows it to enter hard-to-reach places in a small configuration while remaining enough surface area for attachment forces.
The proposed prototype serves as a foundation for further research in the development of reliable and effective magnetic-actuated suction grippers in a variety of configurations.

The MLD massage is a key component of a lymphedema patient’s treatment. Currently, research is ongoing manifesting a transition from system care to self-care by designing robotic sleeves that are able to perform an effective and safe MLD massage enabling the patient to gain a sense of empowerment and ownership over their treatment and time. This research presents an innovative approach towards the MLD treatment by introducing an intermediate step: the bio-inspired design of the patient training education tool (PTET), a tool which aids the patient in performing the MLD massage safely and efficiently by themselves. The PTET is a pliable and slim sheet that easily adapts to the contours of the limb. Exerting manual pressure onto this sheet induces a colour change at a specific pressure threshold, giving the lymphedema patients a visual sign they have reached the required amount of pressure for this type of massage. The mechanism of colour change is inspired by the cephalopod’s dispersion and aggregation of its chromatophores. This study presents the design and validation of the working mechanism of a bio-inspired flexible colour-changing sheet, and first insights into the adaptability of the design variables and their relation to the threshold pressure, threshold indent and degree of colour change.

An intracranial aneurysm is a bulge in the cerebral vasculature. The rupture of an aneurysm results in a brain bleed. As a consequence, most patients become severely handicapped or may even die. Preventive treatment with endovascular coiling is controversial due to the high risk of complications. These complications are partly caused by the current uncontrolled delivery of coils to the aneurysm. While recent developments in microcatheter design allow for improved positioning, no method has been devised to model and control the tension applied by the coil on the aneurysm wall throughout a coiling procedure. This thesis aims to come up with a method to improve the safety of aneurysm treatment.

This thesis presents a new way to dynamically model an endovascular coil and its interaction with a microcatheter and the aneurysm wall throughout a coil deployment procedure. The main advantage of this model is its low computational complexity allowing real-time control computation. A control architecture is presented that enables regulation of the contact force between the coil and the aneurysm wall while obeying the constraints imposed by the equipment and the environment. The presented architecture comprises an augmented energy-shaping controller working in parallel with a constraint preservation controller.

This thesis shows that this control architecture asymptotically stabilizes the aneurysm wall tension at the desired value throughout the coil deployment procedure.

This work provides a basis for modelling and control in future experimental validations. Therefore, this work is a promising first step in the modelling and control of robotic systems for neurovascular interventions and a step forward in the preventive treatment of intracranial aneurysms.

The surgical procedure of tissue extraction from the human body for precautionary or curative measures is common in many medical fields. Currently, aspiration catheters are the golden standard, enabling removal by means of a suction force. By Sakes et al., an alternative mechanism is proposed, transporting tissue based on friction, inspired by the egg-laying structure of wasps. Challenges within these devices comprise clogging and damage prevention, achieving adequate
transportation rates, transportation of tissue with differing elasticity properties and satisfying the dimensional restrictions of Minimally Invasive Surgery (MIS). Due to the vital impact of MIS, a tissue extraction device overcoming the previously mentioned barriers is highly desirable. The goal of this research is stated as follows, ‘design of a continuous tissue transportation mechanism compatible for MIS in which the transportation velocity is independent of tissue elasticity within the young’s modulus range of 1-110 kPa’. The stated elasticity span resembles a large range of tissue that can be encountered during MIS, whilst aspiration catheters are assumed to be suitable for the removal of liquids. Tissue extraction and retrieval are not included within the scope.

To achieve the stated objective, novel ideas are generated from both a dynamic and nature-based perspective and assessed by means of rapid prototyping. Within the final prototype, a cylindrical conveyor belt is created, consisting of a thread wrapped along a tubular body. Due to friction between the thread and tissue, the latter is transported whenever continuously rotating the thread in the direction of removal. Experiments are performed with the proof of principle prototype to investigate the effects of different rotational velocities, instrument orientation, and tissue shape on the transportation velocity of tissue and the corresponding efficiency and reliability. Maximum mean mass transportation rates of 7.75∓0.48, 8.43∓1.50, and 8.90∓0.56 g/min are attained, as a result of transporting tissue phantoms with a young’s modulus of approximately 1-10, 55, and 100-110 kPa respectively. Whether statistically, variance in transportation rates between these categories appears is not determined, as equivalent power supply voltages did not result in identical rotational velocities due to varying thread tension. However, as the transportation velocities match rates of clinically available morcellator and perfect reliability is attained, the potency of the designed mechanism as an alternative for aspiration-based instruments is demonstrated.

Mobile soft robots show great potential for exploration of unknown and hard to navigate environments. Sadly, most of these robots are currently being held back by their power sources and control systems. These components, which are usually quite heavy and bulky, need to be integrated before mobile soft robots can cut their tethers and explore the world autonomously. Soft robots should be mindful of their energy consumption to minimize the requirements on the power supply. However, the efficiency of their actuators is still a not well understood area of research. We attempt to pave the road for future research into this subject by developing a testing protocol based on a simplified analytical model. We built an experimental setup and investigated the efficiency of soft pneumatic extension actuators. We found that actuator designs which reduce axial stiffness produced higher efficiency. Additionally, we found that efficiency increases with load, until it is limited by the buckling load. Unfortunately, these two conditions seem to conflict with each other since a lower axial stiffness also reduced the buckling load. Future actuator designs should therefore try to combine a low axial stiffness with high load bearing capabilities. Also, this research should be extended to different classes of soft actuators as well as investigating non-ideal circumstances. We believe this research aids in the general understanding of efficiency of soft actuators and act as a stepping stone for future research.

Gripping slippery, compliant, and irregular tissues during MIS is often challenging using a conventional gripper. A force grip has to compensate for the low friction coefficient between the gripper’s jaws and tissue surface. This study focuses on the development of a suction gripper as an alternative for the well-known tissue gripper. Suction technology applies only normal forces to grip the tissue without the need to enclose it. Inspiration is taken from biological suction discs. These are able to attach to a wide variety of substrates, varying from slimy surfaces to rough rocks subjected to chaotic streams. The designed suction gripper is divided into two parts; the suction chamber inside the handle where vacuum pressure is generated, and the suction tip that makes contact with the target tissue. The suction tip fits trough a 10 mm diameter trocar, and unfolds in a larger suction surface when being retracted from the trocar. The suction tip is built in a layered manner. Each layer focuses on a specific function to allow for safe and effective tissue handling: 1) Foldability, 2) Air Tightness, and 3) Slide ability. The footprint of the tip focuses on its adaptability to different substrates. Experimental validation of the suction tip’s attachment performance on slippery and flexible phantom tissue showed a maximal attachment force of 3.27±0.15 N. The occurrence of leakage appeared to be the main reason that larger attachment forces are not reached. The proposed prototype of the suction tip provides a base for further research to develop a reliable and effective tissue gripper actuated by suction.

Background: Colonoscopy is a successful screening method to prevent colorectal cancer (CRC). Biopsies are performed from suspicious tissue spots during the colonoscopic procedure to find cancerous polyps in an early stage of the disease. However, taking multiple biopsies is rather time-consuming and requires many repetitious actions from the gastroenterologist. The current state of the art instruments either do not solve this issue or do not meet the user requirements. The goal of this study was, therefore, to design a new endoscopic instrument to store multiple biopsies during a colonoscopy. Methods: The input from different gastroenterologists, together with risk analyses, has resulted in the lists of requirements for the device. These requirements have defined the design space for the development of the instrument. The tip functionalities were subdivided into five design challenges: integrate, transport, remove, store and secure. The solutions for these challenges were combined to generate concept directions. Within these directions, concepts have been created and analysed, which resulted in the final design, 'the Biopsy Containuer'. Different prototypes have been made from this design to evaluate the functionalities of the instrument and receive the opinion of potential users. Results: The evaluation showed that the developed prototype is able to remove a biopsy from the biopsy forceps and store five biopsies without loss or change of order inside the container of the instrument. Besides, potential failure movements were investigated, and they did not result in breakage or malfunctions. The participating gastroenterologists in the user assessment were, in general, pleasantly surprised about the potential of this instrument. Performing six biopsies using the Biopsy Containuer results in a time reduction of 44 %. Discussion and conclusion: When taking the learning effect found during the user assessment analysis into account, the time to perform six biopsies is reduced by 57 %. More research is required to evaluate the influence of bowel tissue on the instrument functionalities and the most suitable handle design. The next prototype iteration can include the use of one single polytetrafluoroethylene (PTFE) tube and laser cutting to create the tip structures. The Biopsy Containuer is able to store multiple biopsies during a colonoscopy, and the potential purpose in endoscopic procedures besides colonoscopy could be useful.

Objective: this paper aims to evaluate the adhesive and frictional properties of the keratinised epithelium on the adhesive pads of tree frogs. Modeling methods: two modeling methods have been developed. One of these methods involves the implementation of discrete fibres in a relatively compliant material matrix while the other method involves an anisotropic hyperelastic material model developed by Holzapfel et al. (HGO model). The adhesional and frictional behaviour of an epithelial cell is evaluated for the contact forces at the interface between the adhesive pads and the interface. These forces are dependent on the tree frog behaviour, which consists of proximal pulling on the limbs and adjustments in the body posture and the position of the limbs. Modeling results: a higher fibre density and fibre-matrix bonding is found to increase adhesive performance. An increase in the fibre-matrix stiffness ratio is found to be beneficial for adhesional performance, while an optimum value for this ratio is found for the frictional performance. The modeling results show that the proximal pulling on the limbs by the tree frog without positional adjustment has no significant effect on the adhesive and frictional performance. An adjustment in the body posture and the position of the limbs, however, is found to significantly increase the adhesive and frictional performance. Experimental methods: samples that mimic the tree frog epithelial composite structure are fabricated. These samples consist of a polydimethylsiloxane (PDMS) material matrix in which acrylonitril-butadieen-styreen (ABS) fibres are embedded. Experiments are performed to measure the frictional and adhesive performance of these samples. The experimental results are used to confirm the modelled results on the influence of the fibre-matrix stiffness ratio and the fibre density. Experimental results: for adhesion, the model results are in agreement with the experimental results. For the frictional response, the agreement between the model results and experimental results is less strong.