In the semiconductor and photovoltaic industries, contactless positioning systems are increasingly employed to handle ultra-thin wafers, minimizing the risk of mechanical damage. A suitable and integrated sensor system would make this handling method more attractive in future applications. This Msc. thesis explores a novel concept in planar position measurement for flat, reflective objects using fiber optic sensors distributed across a measurement plane. This sensor configuration creates light profiles via transmitting fibers and utilizes the reflected light detected by receiving fibers to localize the object's position.
A Gaussian-distributed intensity pattern is first applied to the light profiles to validate this concept, establishing the theoretical relationship between brightness and planar positions. A prototype with a single set of fibers is then constructed to verify the proposed brightness model and determine the optimal, sparsest fiber spacing that maintains adequate resolution. In the next phase, algorithms are developed using simulated sensor arrays to calculate planar degrees of freedom based on the actual positions and brightness values from receiving fibers near the object's boundary. These algorithms are then implemented in a fabricated sensor array prototype, forming a complete distributed fiber optic sensor system.
The sensor's performance is evaluated using samples with varying center positions and orientations, resulting in an average error of less than 1 mm in the in-plane directions. In conclusion, the proposed sensor configuration limits planar position errors to sub-millimeter accuracy. The measurement range is significantly extended, and the sensor element no longer needs to be attached to the measured object. As a result, this system offers promising potential for contactless planar positioning of thin, fragile products with specular surfaces.

Steerable medical instruments are used to reach difficult locations in the body during minimally invasive surgery (MIS). Researching these instruments helps to further improve their performance and reduce their size making them even less invasive. However, developing new technology can be expensive and often complete custom test rigs are build for these instruments. This thesis presents the design, manufacturing and validation of an affordable, open-source prototype test setup for multi-segmented tendon-driven manipulators aimed at stimulating academic innovation of these manipulators. The prototype allows manipulators to be changed swiftly for other or iterated designs. Computer aided design (CAD) was used to create the design and a novel low-cost 3D printed force sensor comprising a permanent magnet and Hall effect sensor was proposed costing only €2.11. The prototype uses readily available off-the-shelf components and custom 3D printed parts that can be manufactured using hobby grade fused deposition modeling (FDM) printers. Despite the prototype working as intended, there are some tolerance issues in the actuation mechanism and viscoelastic behaviour in the printed force sensor that requires more research.
However, the prototype setup already has the potential to be used for preliminary testing of tendon-actuated manipulators. Future work should focus on improving the 3D printed force sensor for enhanced performance and reliability. This work contributes to the progression in testing and validating tendon-driven manipulators.

This research addresses the need to ensure the safety and accessibility of roller coasters for people with lower extremity prostheses. Current roller coasters, particularly floorless roller coasters, pose sig- nificant risks to prosthetic leg users due to the intense forces exerted during the ride. These forces may cause the prosthesis to dislodge and eject, leading to accidents and injuries to riders and bystanders. To solve this problem, this research aimed to develop a product that ensures the secure attachment of prosthetic legs that can withstand the dynamic forces of roller coasters while ensuring user comfort, ease of use, and adherence to safety standards.
The methodology involved conducting G-force measurements on roller coasters, interviews with stake- holders, and analysing different prosthetic designs. A risk assessment was performed to identify po- tential hazards associated with the detachment of the prosthesis. The research led to the development of two primary concepts: the SafeStrap and the MeshSafe. These designs were prototyped and eval- uated under real-life conditions using user feedback from prosthetic leg individuals and testing with a dummy.
The SafeStrap, with its compact design and adaptable components, emerged as the most promising solution, offering a practical and user-friendly mechanism to secure prosthetic legs during roller coaster rides. Its ease of manufacturing, compactness, and versatility make it a stronger candidate for further development into a commercial product. Additionally, the SafeStrap can be adapted for use in other extreme sports such as skydiving, further expanding its potential application.
This research advances inclusivity and accessibility in the amusement and leisure industry for people with lower extremity prostheses by introducing the SafeStrap, a reliable and comfortable solution that enhances their safety and experience in amusement parks.

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 precision and intricacy behind mechanical watches has long captivated horologists and is driven by centuries of innovations. Mechanical watch complications such as chronographs, can further increase mechanical complexity and present challenges due to the reliance on numerous rigid components requiring precise movements. These movements can result in wear, friction, and reliability issues building up over use. Compliant mechanisms offer a promising solution by utilising material flexibility to enable motion with minimal wear, backlash, and a reduced part count. These advantages however come with challenges, such as a more complex integrated design process, limited mobility, and fatigue considerations.

This thesis therefore presents the design, modelling and evaluation of a compliant bi-state switching mechanism designed for fabrication from a silicon wafer and integrated with the horizontal clutch and braking system sub-components of mechanical chronographs. The functional requirements of the chronograph sub-functions include reliable switching between the engaged and braking states, secure gear engagement with minimal misalignment during the engaged state, and precise timekeeping through minimal brake timing delay and slippage of the chronograph seconds hand during the braked state. The design is modelled and validated using both an analytical pseudo-rigid body model and a numerical finite element model. A scaled PETG-based proof-of-concept was then fabricated to verify the performance.

The PETG proof-of-concept demonstrator experimentally showed a robust switching success rate of 99.8\%, stops the seconds hand within 2.4 $ms$, and prevents slippage up to a 2.5g loading case meeting the functional requirement. The gear engagement functional requirement however was not fully meet with a success rate of 95\%. The underlying cause of this issue was identified and recommendations for redesign were provided. Additionally, the simulation model results indicate that the design offers a durable performance with von Mises stress levels within desired limits of under 300 $MPa$. Future works for this design include to develop a functional one-to-one silicon wafer prototype and integrate the mechanisms with additional chronograph sub-functions, such as the minute counter and reset mechanism.

This thesis provides two key contributions. First, it introduces a novel bi-state compliant switching mechanism based on a latch-lock design. This design hold potential applications in MEMS devices, mechanical logic designs, and robotics and is capable of scaling with minimal modifications or impact on performance. Second, as silicon wafer fabrication was desired, a practical methodology was developed to translate the silicon wafer requirements and expected behaviour from the experimental PETG results and scaled demonstrations.

Background: Scoliosis is a three-dimensional abnormal curvature of the spine, with Adolescent Idiopathic Scoliosis (AIS) being the most common type. Current fusion treatment is highly invasive and removes all mobility of the fused spinal segments. To tackle this problem, non-fusion techniques were developed, that try to correct the abnormal spinal curvature while maintaining healthy spinal mobility. The state of the art of non-fusion treatment includes techniques that have highly inefficient methods of correction, contain long and hefty structures leading to large surgical scars, or cause the need for revision surgery. Most importantly though, all of the current techniques have high complication rates. It was therefore deemed necessary to design a mechanism that facilitates minimal invasive and local, non-fusion correction in a mechanically effective way, by applying constant force in the appropriate direction.

Methods: The anatomy and mechanics of a thoracic spinal segment were analyzed, showing the challenges that are at hand. From there, lists of requirements and wishes were generated that initiated the conceptualization process. Concepts were then generated, categorized, and selected after which it was shown that the concept of a single buckled leaf spring with joints was the most suitable. Future vision figures were made showing how an implant could look like that contains this mechanism. The mechanism was then further developed and an experimental setup was designed and built. This setup was used to carry out four proof of principle experiments that examined the viability of the buckled leaf spring as functional mechanism. The relation between thickness and buckling force was tested, as well as the hysteresis of the mechanism. Furthermore, the effect of misaligning
the mechanism both translationally and rotationally has been examined. Finally, the mechanism was placed inside soft tissue phantoms to examine the effect of the presence of surrounding soft tissues.

Results: A buckled leaf spring that fits the size and material requirements was manufactured and the results of the proof of principle experiments show that it manages to create a constant buckling force of desired magnitude for correction. However, misaligning the implant did show effects on the force profile, with the effects of translational misalignment being the most significant. Finally, little hysteresis was perceived, which significantly increased when the leaf spring was placed within a soft tissue phantom.

Discussion and Conclusion: The mechanism is as of yet not suitable for clinical implementation. Further design steps must be conducted and an extensive analysis of the anatomical and mechanical effects of placing the implant against the spinous processes must be carried out. Further recommendations have been made to improve the design and functioning of the mechanism. This study has demonstrated the potential that the mechanism of a buckled leaf spring has in the constant force correction of scoliosis.

Background: Treatment of eye conditions, such as retinal detachment, macular pucker or macular holes, ask for an intervention named ”vitrectomy”. In a vitrectomy, multiple surgical instruments are brought into the eye, to facilitate removal of the vitreous humor. The instruments enter the eye through trocar ports that are placed in the sclera. Post operation, this passageway is removed, leaving an incision wound in the sclera. These wounds that remain after removal may cause complications such as hypotony and endophthalmitis. Current studies suggest that the frequency of these complications decreases when the incision architecture (i.e., the number of incision planes that are used to construct the
wound) , made during insertion of the trocar port, has better self sealing properties. The objective for this study is to develop and verify a surgical instrument that can consistently create the most effective self-sealing scleral incisions.
Method: An analysis is performed that investigates the relation between the incision architectures and the corresponding self-sealing characteristics. This analysis is done through information found in literature and an experiment. In this experiment, incisions with a variety of incision architectures are made in a setup that imitates the characteristics of the
human eye. Based on the analysis, incisions with a bi-planar architecture hold the greatest potential for consistent self-sealing incisions. A set of requirements are formulated that are used to generate a functional prototype that is capable of creating bi-planar incision. This concept consist of a high precision pin and slot mechanism linked to an actuation handle.
Verification of the established requirements and evaluation of the prototype performance are achieved by incisions in silicone slabs (i.e., eye phantoms).
Results: The defined Bi-planar architecture is set to have an oblique plane of 0.500 mm, a vertical plane of 0.250 mm and the angle between the two planes of 60.0◦. The Bi-Planar Incision Mechanism showed to have an mean oblique plane of 0.530 mm (SD = 0.043), a mean vertical plane of 0.248 mm (SD = 0.0286) and a mean angle of 60.08◦ (SD = 2.40).
The incision were performed with an average time to completion of 5.0 seconds (SD = 1.5).
Conclusion Using the Bi-Planar Incision Mechanism showed to be a successful method to make the desired bi-planar incisions. The result showed precise, accurate and fast incisions. The next step is to validate the self-sealing statistics in conditions that resemble those found in the operation room.

Minimally invasive surgery (MIS) has several advantages over conventional surgery, including reduced damage to the body, less pain, lower infection risk, and faster recovery. However, MIS reduces the amount of space in which clinicians can operate within the body. This often forces them to work around delicate anatomical structures. A new type of instrument that can manoeuvre the body with snake-like movement, also called follow-the-leader (FTL) locomotion, could be a solution. A challenging design aspect of FTL instruments is to conserve the instrument’s shape accurately while the instrument propagates into or retracts from the body. This thesis presents a new device, called the Dullomatic, which can conserve 2D shapes and fits inside an instrument’s flexible shaft. The Dullomatic contains two adjacent mechanical shape memories which alternate between a flexible and rigid state, together forming a shaft. The device can be operated such that it conserves the shape and shifts the shape backwards as the device propagates forwards, or vice versa, to attain FTL locomotion. A prototype of this design was manufactured at a 2:1 scale containing 3 segments per shape memory. This prototype was evaluated by performing four FTL steps over a curved trajectory and measuring the position of the segments after each step. The results show that the device could be operated to accurately follow this path with FTL locomotion. Further research is required to enhance its user interface and investigate its potential for miniaturization. The Dullomatic forms an interesting addition in the field of FTL devices and might be able to aid in further reducing the invasiveness of surgery.

Treatment of prostate cancer can be done by performing brachytherapy, where radioactive seeds are transperineally implanted in the prostate via needles. A known problem during treatments with needles is the risk of targeting errors caused by the deviation of the needle from the planned path in the prostate. One of the main sources of this error is the displacement of the prostate due to insertion of the needle. Often, stabilisation needles are used to stabilise the prostate, however, stabilisation needles alter prostate properties, damage tissue, and do not fully reduce prostate displacement. Therefore, in this study, we propose and evaluate an alternative solution that stabilises the prostate without additional tissue damage. The stabilisation solution is a modular suction cup referred as the ProSTATIC, which can be transperineally inserted via a 5 mm incision to attach to the prostate within the rectoprostatic space. The ProSTATIC has a multi-holed design consisting of three structural layers with their functionality; (1) the top to maintain the pressure inside of the suction cup and provide for structural stability, (2) the footprint to adapt and form a closed seal with the prostate surface, and (3) the self-regulating valves to increase the attachment reliability on irregular surface textures. For the footprint, we experimented with micro-patterns and suction hole sizes to increase the overall grip force. The prototype was completely fabricated out of biocompatible and ultrasound-compatible silicone rubber using mould casting. An experimental evaluation showed that the self-regulating valves work only on healthy prostate phantom. On healthy-tumorous and full tumorous tissue phantoms the suction holes deform, hindering the optimal working of the valves and leading to air leaks. Furthermore, only the prototype with the base footprint with enlarged suction holes (from 2 mm to 3.2 mm diameter) and radial ridges was able to generate a maximum grip force higher than the required 5 N for stabilisation and demonstrated that prostate displacement was reduced by 75% during needle insertion without the use of the ProSTATIC. The prototype proposed in this study forms an initial breakthrough in safe and reliable volumetric stabilisation of the prostate during brachytherapy.

Immobilisation devices are commonly used for the treatment of extra-articular distal radius fractures. However, conventional immobilisation devices such as plaster casts and fibreglass casts may lead to complications and discomfort. Another disadvantage of present-day conservative fracture treatment is that the casts have to be replaced after one or two weeks when the swelling subsides. In this thesis, an alternative distal radius fracture treatment device was designed, prototyped and evaluated. The main goal of this design was to make the immobilisation device adaptable to swelling while fitting most patients.

The device was designed using a three-step iterative design process and four successive iterations. The steps that were performed in each iteration were setting the requirements, generating solutions and evaluating and deciding. The development of the design was done in the following steps: generating design directions, developing a conceptual design, embodiment of the design and detailing the design. A prototype of the device was created to demonstrate the device's functionality. The design and the prototype were evaluated using diverse methods. Ten healthy volunteers provided feedback after wearing the device, an orthopaedic surgeon offered his expert opinion and several aspects were assessed using calculations and literature. After the prototype was made and evaluated with healthy participants an additional iteration was done to improve the function of the design.

In the first stage, 16 design directions were generated, and the three most promising design directions, the Cushioned Clamp, the Filled Sleeve and the Friction Slots were selected. In the next stage, these design directions were further developed into conceptual designs. The Cushioned Clamp was chosen as the best solution. The Cushioned Clamp consists of interconnected rings around the forearm, wrist and hand with pads that can be adapted in height. In the next step, an embodied design was made. This design had a large offset on the arm and therefore the rings were made adjustable during the detailing phase. Also, the usability of the device was improved. The final design is a device with three adjustable rings with pads that can separately be adjusted for swelling of the limb. The rings are connected with telescopic mechanisms. With a few additional size parts, the single immobilisation device can be adapted to fit 90\% of the adult population. The device was prototyped using aluminium, SLA-printed Form Tough 1500 and Draft Resin, FDM-printed PLA and foam. The prototype allowed too much movement of the wrist, this was addressed and solved after the tests with healthy volunteers. The device is reusable, which reduces waste as less material is used and disposed of. Furthermore, the device is waterproof which reduces skin complications and improves hygiene. The device allows thumb movement which improves the hand function. Furthermore, the mass of the device is 437~grams, which is less than a conventional plaster cast. Volunteers were generally satisfied with the device and the device is quick in application. The medical experts shared concerns about comfort, robustness and applicability for different fracture types. During the improvement phase, several aspects of the device were discussed and improvements were made. Most importantly, additional telescopic mechanisms and connections were designed to prevent movement in the device. Further, the comfort, X-ray permeability and play in the prototype were addressed.

The device is adjustable and adaptable to swelling while allowing skin ventilation. Further, good hand function, a sustainable design and clean applications are advantages of this design. However, the functionality of the design and the prototype can be improved by reducing play and improving robustness. Furthermore, the comfort of the device can be increased by making the device more compact and distributing the pressure better.

The Lunar Zebro is a small moon rover that needs an advanced chassis to endure the harsh environment that the moon brings. To arrive at a solution for such a frame or chassis creativity and hard work are necessary. Whereas hard work is a given, creativity is not and it may need a helping hand. Design synthesis methods, of which brainstorming is a basic example, aid engineers and designers with reaching better solutions. Currently, however, which method works best for a given scenario is unknown. The purpose of this research is to determine which synthesis method works best for concept generation, with the focus lying on generating innovative solutions for frame design. A meta-method is created to evaluate the performance of different synthesis methods when applied to design cases. This meta-method consists of executing fifty case-method combinations, built up from pairing ten design synthesis methods with five design cases, which are focused on frame design primarily. The combinations are then evaluated using a self-made rubric. In the end, it became apparent that different methods apply well at different stages of the design process and at different system levels. Some work well to orient, understand the supersystem and therefore have an positive yet indirect influence on the final outcome. Some work well to generate concepts, bring new ideas at system level. Others apply well after a concept is already generated, only being useful to improve subsystems.

Background: Minimally invasive cancellous bone biopsy is a common medical procedure in which a needle is used to extract a piece of cancellous bone for examination. Unfortunately, this procedure is not always successful, as sometimes the biopsy can slip partially or completely, necessitating a new biopsy. The occurrence of these errors is not well documented, but the main causes are believed to be an inadequate grip on the biopsy by the current golden standard or improper use of the additional instrument of the golden standard. This study aimed to design a novel mechanism for use in a biopsy needle, with the goal of combating the causes of the errors by providing an integrated design that guarantees the extraction of a biopsy.
Methods: The design process was explored by plotting the potential variations onto a design tree. This resulted in four distinct concepts. Criteria were established to evaluate the concepts. The Cam-follower concept was chosen as the final design. This mechanism was then constructed into a functioning prototype. This prototype was tested in a visual experiment and in a material experiment using gelatin and artificial bone tissue phantoms.
Results: The cam-follower mechanism was able to close off 89% of the end of the needle prototype. It was successful in extracting complete biopsies from the gelatin tissue phantom. The analysis of the softest bone was challenging due to the lengthwise compression of the biopsies. The needle prototype had difficulty penetrating the medium hard artificial bone and broke beyond use during these tests. The needle prototype was not put through its paces on the most difficult artificial bone type prepared for the experiment because of the harm it had sustained.
Discussion and conclusion: The Cam-follower mechanism is an integrated instrument that is intended to improve the efficacy of minimally invasive bone biopsy instruments. The current needle prototype was able to extract biopsies of higher quality and size from the gelatin tissue phantom compared to the golden standard. However, it failed to extract a viable biopsy from the artificial bone tissue phantoms, meaning that the design did not meet its goal. It is possible that the tissue phantoms used in this study did not accurately replicate real bone tissue, which could have impacted the results. Additionally, the main focus of the design was on the mechanism when the bone was already penetrated, so any issues that arose during penetration were not addressed before the material test. It is recommended to further refine the design with these results in mind. Small changes, such as incorporating elements from the golden standard like the tapered end and the sharpened cutting edge of the outer needle, could have a positive effect and enable the cam-follower to guarantee extraction of a biopsy, which would open the door to a clinical application.

Focal laser ablation is a new, promising method to treat tumors. The current focal laser ablation approach is to insert an optical fiber into the patient using rigid needles. A side effect of this approach is that during the needle insertion, tissue damage occurs. The larger the diameter of the needle, the more tissue damage. If the diameter of a rigid needle is reduced, the risk increases that buckling occurs during insertion. Buckling can result in tissue damage due to unwanted movements of the needle tip. By using wasp-inspired, self-propelling needles, the size of the needles can be reduced, thereby reducing tissue damage, while preventing needle buckling. The needle can advance through tissue with no net insertion force by moving parallel needle segments in a specific order. In this work, we present the design and evaluation of an MRI-compatible, pneumatic actuation unit for such a self-propelling needle. A prototype was created that was, except for the screws that were used, fully 3D printed with MRI-compatible materials. Guidelines were formed on how to approach such a 3D-printing process. The screws were also made of an MRI-compatible material. The prototype has the option to change the distance that the needle segments travel each cycle, called the stroke. By using a control unit for the air supply of the prototype, the needle segments were moved automatically. The needle consists of six needle segments with a diameter of 0.25 mm. We tested the performance of the prototype in 10 wt\% gelatin tissue phantoms in terms of the slip ratio of the needle with respect to gelatin tissue phantoms. The results showed that the prototype was functional for small strokes (i.e., 2 mm and 4 mm), as the needle was able to advance through 10 wt\% gelatin tissue phantoms using the self-propelling mechanism with a mean slip ratio of 0.912-0.955. The prototype is the next step in developing self-propelling needles suitable for focal laser ablation to treat tumors.

An improvement for pedicle screws would be if the screws can directly transfer their forces to the strong cortical bone of the vertebra, rather than through the softer cancellous bone. This approach requires the creation of a curved trajectory through cancellous bone. The goal of this project is to adapt the flexible oscillating drill design of Müller to a steerable drill that can create a curved hole in artificial cancellous bone.
The oscillating drill tip is a cylinder which oscillates rotationally around its centre axis. The cutting direction is radial. This drill design constantly produces a sideways force since the cutters produce a friction force tangential to the cylindrical wall. The friction force on the forward stroke is currently cancelled out by an equal and opposite force during the reversed stroke. Introducing a difference in phase or amplitude between the two translationally oscillating inputs to the drill head can create a force difference between the forward and reverse stroke, which provides a net sideways steering force over many repetitions.
A prototype drill and accompanying oscillator have been designed and built to further research the effects of the amplitude and phase difference on the drill motion and drilling performance. The oscillator outputs two oscillations that can be individually adjusted in stroke length and their relative phase angle. The output stroke lengths can be set to 0.75, 0.50 and 0.25 mm. The phase difference can be adjusted in 18° increments between 0° and 360°. The drill consists of the cylindrical drill head and two parallel leaf springs that slide longitudinally and thereby transfer the motion of the oscillator to the drill head.
The results showed that the drill got embedded in the drilled hole which is insufficient for measuring a steering effect. Therefore, two alternative drill designs were proposed and evaluated to increase the drilling depth. The design adaptation that provides the most promising result, is to drastically lower the stiffness of the connection between the drill head and the leaf springs. An amplitude or phase difference applied by the oscillator causes the drill head to produce a different motion pattern. The pattern from the amplitude difference shows a decrease in the deviation distance which is expected to have a diminishing effect on the effectiveness of the drill. A phase difference of 144° between the two oscillations, causes the drill to produce an oval motion pattern which is expected to be the most effective in generating a steering effect.
This project provides a great basis for the future development of a drill that can steer without a steering actuator. The next step forward with this design should be to incorporate hinges between the leaf springs and the drill head, to maximise the rotational motion of the drill head.

When treating a Chronic Total Occlusion (CTO) via Percutaneous Coronary Intervention (PCI), a guidewire first needs to be passed through or around the occlusion, a task requiring considerable skill and clinician experience. Proper backup support for the guidewire being used by the clinician is a prerequisite to prevent buckling or uncontrolled movement. Three different concepts that can vary their stiffness were generated, prototyped and evaluated against each other. Finally, a mechanism was designed that can vary its stiffness drastically by radially jamming wires together between a braided sheath and a radially rigid core that is also flexible in bending. Friction between the wires and the steerable segment generates the stiff configuration. If the braided sheath is released the wires can move along each other and the mechanism is flexible. The variable stiffness ability was tested by clamping the mechanism into a frame while applying a load to the distal tip. This resulted in a force-displacement curve that was 20 times stiffer in the stiff state than in the flexible state. The use of a braided sheath in a Variable Stiffness Mechanism (VSM) is an effective and
simple way to obtain variable stiffness. The proposed design is a step forward in the developing process for VSM for cardiovascular applications.

Loosening of pedicle screws after spinal fusion surgery can lead to serious complications and may prevent fusion between vertebrae. This problem, which has increased in recent years, is a more frequent problem in patients with osteoporosis. In this study, we explore the possibility to use an expanding in‐pedicle anchor with the goal of increasing the contact area of the in‐pedicle anchor with the pedicle cortex to reduce toggling. Toggling is the rocking motion that can occur when an in‐pedicle anchor is subjected to lateral forces that can occur during the patient’s daily activities. A stainless steel scaled‐up 2D proof‐of‐principe prototype was developed and manufactured consisting of a central bolt with flattened sides, a nut, and ten sliding wedges. The wedges expand by applying a compression force by tightening the nut. In order for the prototype to reach the pedicle cortex, it needs to compress the surrounding cancellous bone first. It was shown in experiments that the proof‐of‐principle prototype was able to compress 5 and 10 PCF Sawbones solid foam, which corresponds to osteoporotic human cancellous bone. The proof‐of‐principle prototype was able to make contact with the top and bottom of a custom‐made 2D pedicle model where a conventional screw would have been limited to contact on the two flanks. The proof‐op‐principle prototype showed a better resistance
to lateral loads than an unexpanded model with the same dimensions. The proposed in‐pedicle anchor shows potential for improved resistance to caudocranial toggling by increasing the number of contact points with the pedicle cortex. The use of an in‐pedicle expansion to prevent toggling holds a promising future for possible clinical applications.

The spine is an intricate and crucial part of the human body. Unfortunately, spinal conditions such as scoliosis and trauma can cause instability and deformity to the spine. Patients can experience discomfort and pain. Spinal fusion surgery is used to repair and correct severe cases. During this procedure the vertebrae are fused to prevent them from moving relative to each other, thus increasing stability. Pedicle screws and rods are used to lock the vertebrae together and bone grafts are inserted to grow the vertebrae together. The insertion of the pedicle screws is a complicated procedure where breaches of the cortical wall can occur leading to tissue damage and possible complications for the patient. To prevent breaches, guidance methods have been introduced. However, these methods have considerable disadvantages in terms of patient safety and costs. Introducing an alternative guidance method, this master thesis investigates the development of a drill that uses diffuse reflectance spectroscopy (DRS). DRS is a spectroscopy method that uses diffuse reflection to determine the structural and chemical properties of a biological sample. By differentiating cortical and cancellous bone based on their fat content, directional feedback is provided to guide the user during the drilling of the pedicle. In this work, a drilling prototype was developed that uses DRS to provide directional feedback. The prototype uses integrated optical fibres to sense in two different directions: along the drilling direction and at a 90°angle to the drilling direction. This allows the device to sense the surrounding volume and provide feedback on the type of bone the drill encounters. A 3D Monte Carlo RTE solver, MCMatlab, was used to simulate photon transport inside biological tissue. Core-to-core distances larger than 1 mm were investigated to find if the corresponding look-ahead would increase distances as well as different fibre configurations for a prototype. Multiple design concepts were proposed and assessed. A prototype was made and tested on a 2-layered bone phantom. The results indicated a frontal look-ahead distance of 3.6 mm for a 4 mm core-to-core distance as well as a 1.5 mm sideways look-ahead distance for a 1.5 mm core-to-core distance. The prototype provides a proof of concept that DRS can be integrated into a drill in such a way it can provide directional feedback. Although results are promising, improvements can still be made in the collection of data to provide consistent results for directional feedback.

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.

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.

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.