In many countries, Vacuum-Assisted Delivery (VAD) is the most common technique for instrumental vaginal delivery. Current VAD devices require the formation of a typical chignon on the infant’s scalp to achieve the necessary traction forces. This chignon, a swelling on the infant’s scalp, can lead to complications and, in severe cases, even death. This study addresses the question of how a new design for a VAD suction cup can reduce chignon formation while maintaining excellent adhesive performance. Three 3D-printed flexible suction cup designs with varying flexible lattice structures were designed to minimize chignon formation, and a bellow-shaped sealing lip was used to enhance the sealing performance. The performance of the novel designs are tested on an infant head surrogate and compared to a replica of the current commonly used Kiwi OmniCup®. Results indicated a significant reduction in scalp deformation, with the chignon volume ranging from 6.2% to 15.5% of that observed with the Kiwi replica. While the proposed suction cup designs show promise in reducing neonatal injuries by reducing the chignon formation, future work should focus on achieving a larger maximum traction force.

Brachytherapy is a type of internal radiation therapy that is used to treat cervical cancer. It involves the application of a radioactive source in close proximity to the tumour. This can be done either by directly inserting the source into (or close to) the tumour using interstitial hollow needles, or by loading the source into an intracavitary applicator that is placed in the vaginal cavity. Standard applicator types may lead to suboptimal radioactive source placement, possibly resulting in underexposure of target volumes and overexposure of organs at risk, especially in advanced cancers. Customised applicators and optimised needle channels based on the patient's MRI/CT data could enhance conformity between target volumes and prescribed isodose. Hence, the goal of this project was to develop and validate a design for a 3D-printed brachytherapy applicator which geometry is based on the patient's vaginal cavity and which features optimised interstitial needle channels based on the patient's anatomy and tumour location.

Various analyses have been conducted which have led to the establishment of a list of requirements for the applicator design. Based on this list of requirements, two conceptual designs have been presented: one fully 3D-printed design and one design that is clicked on the Geneva ovoid tubes. Through the creation of prototypes, these conceptual designs have been refined into two final designs which were manufactured in PA12 using selective laser sintering. The dose attenuation properties of PA12 were evaluated and compared to that of water. Furthermore, the potential needle positions within the proximal end of both designs have been analysed. For both designs, a final prototype based on a phantom's vaginal cavity geometry has been created. The usability of these prototypes has been tested by three radiotherapist-oncologists, who also provided feedback on the designs. Upon analysing their feedback and the outcomes of the other evaluations, recommendations for future designs have been formulated.

The conducted dosimetry experiment yielded a maximum difference of 0.8% between the average percent dose depth curves of water and PA12, which can be considered a water-equivalent response. This allows PA12 to be used as the material for the applicator. The result of the potential needle position analysis suggest that the first design provides more space for personalised needle channels in the top of the applicator compared to the second design. The three radiotherapist-oncologists validated the usability of both final prototypes.

Two designs of a patient-tailored 3D-printed brachytherapy applicator containing optimised interstitial needle channels based on the patient's anatomy and tumour location have been presented, produced and validated. Based on the outcomes of the conducted evaluations, there can be concluded that the first concept shows the most promise to be used as a design for a patient-tailored 3D printed brachytherapy applicator. However, to ensure the proper functioning of the working principles, further development is required. If the recommended improvements are implemented, the design has the potential to be used as applicator in the treatment of cervical cancer.

Colonoscopy is a widely used endoscopic procedure to diagnose colorectal cancer (CRC) which is considered the fourth most common cancer in the US and the second most common cancer in Europe. Colonoscope, used in colonoscopy, consists of a thin flexible hollow tube that is inserted into the rectum of a person and propagated through the entire colon. The disadvantage of the current procedure is that the colonoscope has to be pushed from outside to move through the colon resulting in recurrent looping of the colonoscope due to buckling. Recurrent looping inflicts the risk of tissue damage and is responsible for approximately 90% of the pain experienced by patients during colonoscopy. Research was carried out to create self-propelling colonoscopes which would eliminate the force required to push the device from outside. Inspirations were taken from the locomotion of earthworms to develop self-propelling colonoscopes however, the device’s propulsion was hindered due to friction and low axial stiffness of the colon wall. In this study, a proof of concept for a self-propelled colonoscopic device inspired by the ovipositor of wasps was conducted which resulted in the development of a prototype. The prototype was tested in a colon-simulated environment and it was able to successfully propel through the prepared colon phantom after an initial manual run through the colon phantom. The requirement of an initial manual run was speculated to be due to the capillary adhesion and uneven oil spread in the colon phantom. The device had an average velocity of around 5.68 mm /s inside the colon phantom with an average efficiency of 72.5%. In the future, the prototype has to be tested in an actual colon to assess its functionality and evaluate the propulsion efficiency of the prototype in a real colon.

In the field of soft robotics, rigid joints and links are replaced by soft, deformable elements, This causes soft continuum robot arms to excel in unpredictable environments, but to face challenges during control and shape reconstruction. The sensing ability present in octopus suckers provides inspiration for solutions. Octopuses employ their suckers not only to strengthen their grasp but also as tactile sensors to control the shape and position of their soft arms. This has motivated researchers to integrate artificial sensorized suckers in soft continuum robot arms Although various sensorized suckers have already been developed, their employed sensing methods tend to be low in resolution and are often poorly embedded into the overall sucker architecture. In this work, these limits are overcome by presenting an octopus-inspired suction cup with integrated high-resolution tactile sensing abilities. This is achieved by utilizing the Chromatouch Principle, which relies on embedding colored markers in the suction cup membrane. Tracking these markers with a camera produced tactile images containing useful information about forces, deformations and interactions with objects. Fabrication with multi-material additive manufacturing enabled direct integration of these markers into the suction cup membranes. We demonstrated the design’s basic functionality by conducting pull-off and pickup tests. The design exhibited a normal pull-off force of 9.53 N and a shear pull-off force of 5.28 N. It was also able to successfully pick up both flat and curved objects. The sensing ability was showcased by training a Convolutional Neural Network to learn the relationship between the camera images and the orientation of the suction cup with respect to a touching substrate. Using a spherical coordinate system, the orientation could be predicted with an error of less than 2 degrees for latitude and less than 9 degrees for longitude. This performance was validated by using the trained network to successfully correct the orientation when picking up objects under an angle. For a single suction cup, this ability can be utilized to correct the orientation and achieve perpendicular contact with an object, crucial for achieving a seal. On a larger scale, the integration of multiple suction cups in soft continuum robot arms has the potential to form a representation of the arm shape as a whole. It can thereby contribute to overcoming the control challenges faced in the field of soft robotics.

Endoscopic instruments are integral components of minimally invasive procedures, widely used for diagnoses and treatment of diseases. When navigating the endoscope, it should experience a minimum of friction, while an increase in friction is beneficial for performing the medical procedure. Friction can be reduced by squeeze film levitation, where air is trapped and pressurized between two surfaces by vibrating one of these surfaces. The squeeze film levitates the two surfaces away from each other, hereby reducing friction. Squeeze film levitation between a rigid curved surface and a soft surface is still poorly understood. Also, a proof of concept of a friction modulation mechanism for endoscopes is not yet available in the research literature. Therefore, this paper describes the design and experimental validation of an ultrasonic vibrating ring that can actively modulate friction by generating a squeeze film. On a steel surface, the friction is reduced considerably. However, on the two soft surfaces described in this paper, the reduction of friction is absent.

Spinal fusion surgery is applied, amongst other reasons, to correct unwanted curves in a spine hampered by scoliosis. During spinal fusion surgery, holes in the vertebra must be drilled, after which pedicle screws are placed. Traditional drilling only allows for the formation of straight holes. Ill-placed trajectories cannot be course-corrected, leading to repositioning the drill and starting again in the, weakened by the first attempt, vertebra. This thesis aims to develop a drilling method that will allow for the application of trajectory control during operation. This will form the first step towards a new spinal surgical instrument that could be used for course-correcting during spinal drilling or form curved holes applicable for new state-of-the-art alternate bone anchors.
The proof-of-principle instrument designed and fabricated in this thesis consists of an impulse generation part, a bendable tube with a saline medium, and a working head, which will perform the impacts on the bone tissue. The method consists of drilling using the repetitive impact of a solid round tip with a diameter of 4 mm. Through the use of a bendable impulse transmission tube, the instrument allows for the application of steerable drilling. The impulse will be generated by a manual compressed and released compression spring. This impulse will be translated into a hydraulic pressure wave; whereafter it will travel through the liquid medium of the tube, ending at the working head, which translates it into an impact on the target tissue.
The method has been proven to work in every state of curvature of the transmitting tube, ranging from 0 degrees till 90 degrees. Furthermore, almost 20% of the desired impulse output found in this thesis, 0.077 Ns, that would allow for high-speed drilling, 0.3 mm per strike, was reached. A linear increase in impulse output was found, correlating with the linear input increase, suggesting plausible higher impulse output magnitudes could be possible. In the future, the instrument's efficiency should be increased, as a mean efficiency of 3.5% was achieved, caused mainly by leakage of the saline filler and high friction with the mechanisms in the tube. All in all, the method shows great potential to be utilised as a future trajectory controlled bone drilling instrument.

Abstract—Spinal fusion surgery is an operation in which two or more adjacent vertebrae are rigidly connected, with the goal to remedy spinal instability, deformation of the vertebrae, or a herniated intervertebral disc. Vertebrae are conventionally fixated by means of pedicle screws, the downsides of which are accidental cortical wall breaches during drilling and poor holding strength of the screw. The holding strength of the bone anchor may be improved by increasing its contact area with the hard cortical wall of the vertebral body. To accomplish this, a curved hole needs to be made along the inside of the cortical wall. This research presents the design, manufacturing, and testing of a bone drilling device, that is flexible in one plane. To this end, the drill was developed on the basis of the tsetse fly’s proboscis, which is a mechanism that uses a cutting surface with its axis of rotation perpendicular to the drilling direction. Implementing this cutting motion has several advantages over conventional drilling: It facilitates using leaf springs as a flexible transmission, and it is not limited to drilling round holes. A prototype was built and tested on Sawbones closed cell foam, which closely mimics the mechanical properties of the cancellous bone found in human vertebrae. The prototype was capable of effectively cutting through foam with densities up to 10 pounds per cubic foot (PCF) with a feed rate of 50 mm/min. The ability to deflect off and follow a simulated cortical wall was also tested, and proved to be effective up to an insertion angle of 15˚. The bio-inspired drilling device presented in this research opens up new possibilities in the development of flexible drilling for a wide variety of orthopaedic applications.

Cable Driven Parallel Robots, or CDPRs, might provide art historians and curators with an improved automated way of scanning 3D art objects. This application requires CDPRs to rotate around a 3D object with large panning and tilting, while avoiding collisions. While no designs exist for this purpose, this article investigates and proposes new cable robot geometries. First, we built a workspace model to quantify the performance of a design. A brainstorm and the ACCREx method then provided us with over 100 promising robot architectures. Their subsequent testing with the workspace model revealed the nine most promising architectures. Lastly, a geometry optimization resulted in the most favourable CDPR geometries. It appeared that mainly cable force limits, cable-statue and platform-statue collision are limiting the workspace of the CDPRs. In the end, the best enclosing and non-enclosing design are capable of reaching 29% and 16% respectively of the required 180 degrees workspace around the statue. Without extra panning and tilting these percentages are 79% and 66% respectively. Both designs show to which extend a statue can be scanned by a CDPR from one configuration.

This thesis contains two contributions to the stabilization of visually guided robotic lampreys: the head stabilization method and the head-led target tracking design. Both approach the problem that camera inputs, attached to the head segment, are disturbed due to the participation of the head in the locomotion gait of the robot. Head stabilization is designed to stabilize the head segment itself, and head-led target tracking is designed to stabilize the target in the field of view of the cameras. The head stabilization and head-led target tracking designs are build upon the Ijspeert model. The Ijspeert model is an biologically inspired oscillator-based central pattern generator, capable of producing locomotion signals to achieve a lateral undulation gait. Analysis of this Ijspeert model is done by rewriting the model as a network of Kuramoto oscillators. This analysis concludes with a proof for the convergence of the phase differences of the Ijspeert oscillators. Although methods that mitigate the head stabilization problem for robotic lampreys have been designed before, the head stabilization method in this thesis approaches the head stabilization problem as a control problem for the fist time, to the best of our knowledge. The head stabilization method is designed to align the head segment with the average body direction, by providing head stabilizing parameters to the Ijspeert model. Perfect head stabilization is achieved, under the assumption that the motor dynamics are instant. Even though head stabilization is not perfectly achieved in reality with non-instant motor dynamics, we have verified that the head stabilized Ijspeert model is an improvement in terms of head stability, compared to the Ijspeert model without head stabilization. The designed head stabilization method is applied to a novel head-led target tracking design. This method combines a forward locomotion gait with a turning controller to perform target tracking, and is designed to increase the accuracy of visual information by directing the head segment towards the target. The head-led target tracking design is verified by placing the robotic lamprey in a virtual fluid environment with a target, which showed that the target is reached by the robot. Furthermore, the head-led target tracking design is compared to a design from the literature that does not direct the head segment towards the target. The head-led target tracking design shows improvements to the design from the literature in terms of the used performance measures.

Lateral torsional buckling (LTB) of I-beams is an established buckling phenomenon in civil and structural engineering known for causing structural failures. However when a buckling instability is present the structure contains a form of negative stiffness. Due to the observed tendency of I-beams subject to LTB to twist about their longitudinal axis it is suspected that such I-beams contain a form of negative rotational stiffness about their longitudinal axis. Rather than considering LTB as a failure mode for structures, this work aims to investigate the potential of cantilever I-beams subject to LTB having a reduced rotational stiffness about their longitudinal axis with minimal lateral deflection on demand by subjecting the beam to LTB. By minimising the lateral deflection the longitudinal twisting behaviour approaches the behaviour of a compliant rotational joint. The occurrence of negative rotational stiffness in the buckled state is verified and a parameter study is executed to evaluate the stiffness reduction and co-occurring lateral deflection by means of 1-dimensional finite element modelling. Finally an optimisation is performed to obtain a beam with minimal lateral deflection and a significant reduction in longitudinal rotational stiffness. The simulated behaviour is experimentally validated. The simulation and experiment showed that rotational stiffness can be significantly reduced through LTB. Additionally the experiment verified the significant reduction of lateral deflection for the optimised beam. Overall this work forms an initial step towards the use of reduced rotational stiffness of beams by exploiting lateral torsional buckling.