Progress in minimally invasive surgery increasingly demands tools capable of precise, dextrous manipulation, motivating the development of miniaturised, steerable systems. Such systems have been explored in the past, yet most have shortcomings in their controllability. This thesis presents the design and realisation of a mechanical control unit for a cyclically substitutable, parallel-segmented surgical tool intended for minimally invasive procedures. The developed device, named the Cyclical Snake Controller (CYSCO), introduces a single intuitive slider to drive segment substitution and cartridge shifting. The design emphasises simplicity, compactness, and reliability by incorporating only a few moving parts, with the slider-block and stairbeam mechanisms enabling continuous cycling of tip segments. A prototype was constructed featuring a 10 cm snake-like tip comprising five active segments and five stored segments. Performance testing demonstrated that the prototype completed predefined curved paths in mean times of 48 seconds for a C-curve and 45 seconds for an S-curve. Targeting accuracy showed absolute maximum mean errors of 0.5 mm for the C-curve and 1.6 mm for the S-curve, while the maximum footprints were measured at 31.65 mm and 33.27 mm respectively, validating the feasibility of the concept. This study is a strong demonstration that intuitive, mechanically actuated segment cycling is feasible and provides a solid foundation for further development.

Gastroschisis is a congenital abdominal wall defect that develops in early gestation and causes the fetal abdominal organs to herniate into the amniotic environment. A distinction is made between complex and simple gastroschisis (SG) to predict the outcome for affected fetuses. Complex gastroschisis (CG) is associated with significantly higher morbidity and mortality rates compared to SG.

Even though 90% of affected fetuses with gastroschisis survive, efforts have been made to decrease serious gut-related health problems with the development of fetoscopic repair methods after repositioning of the bowel. So far, no results have been published on a procedure demonstrating successful closure of the abdominal wall defect. Recently, an innovative new approach has been developed that expects to be able to close off the abdominal wall defect using a silicone ring with membrane. This method requires no sutures and therefore has great potential in lowering mortality rates for CG. This method still lacks an instrument for insertion into the uterus and direct placement into the abdominal wall defect. Therefore, the goal of this thesis was to provide a proof of principle for the design of an instrument that enables the insertion and placement of the silicone ring with membrane during a fetoscopic repair procedure for the swift closure of the abdominal wall defect in CG.

At the start of the development of this instrument, the future surgical procedure was mapped out and a list of requirements was compiled. Several concepts were generated and developed until a final concept was selected. The instrument was named Intrauterine Ring Insertion System (IRIS). Prototypes were made of the designed instrument and the developed silicone patches. These were used in validation experiments to test whether the concept met the set requirements.

The experiments demonstrated that the new patches were able to close off the abdominal wall defect during and immediately after fetal intervention similarly to the original silicone ring with membrane. The experiments also showed that most (80%) of the new patches could be deployed into the abdominal wall defect with the use of the developed instrument. These tests used a validation model of a 24-week-old fetus with CG. However, loading of the patches into the instrument has not yet been successful. With the results of the experiments, the most optimal patch was chosen.

The goal of thesis was partially achieved, with successful placement but failed insertion of the silicone patch. The instrument-patch compatibility needs to be improved to able to complete the whole goal. The patch and instrument must be developed together as a system to get the best results. Several improvements have been suggested such as thinner graspers with increased grip, a pull or push loading mechanism and a thinner, more flexible patch. Further testing is needed to be able to use the innovative method for treatment of CG. These studies include a material study, preclinical tests in a fetoscopic treatment environment and animal studies. Lastly, a clinical trial must be completed to evaluate if the procedure can be used in humans and if it has the intended outcomes.

Introduction: Implant-associated infections (IAIs) remain a critical challenge in orthopedic surgery, driven by biofilm formation and rising antimicrobial resistance (AMR). Localized, on-demand drug delivery systems offer a promising alternative to systemic antibiotics by providing spatial and temporal control over therapeutic release. This study optimized a thermoresponsive hydrogel system based on Pluronic® F-127 to achieve four specific goals: enable on-demand activation via an alternating magnetic field (AMF), reduce the gel-sol transition temperature, enhance aqueous stability, and suppress passive release.

Methods: Hydrogels were formulated using 20 wt.% Pluronic F127 (20PF127) with sodium alginate (SA), calcium chloride (CaCl₂) for ionic crosslinking, and superparamagnetic iron oxide nanoparticles (SPIONs) for magnetic responsiveness. The formulations were evaluated using the inverted tube method for gelation, stability assessment under physiological conditions, and release kinetics studies under both passive and on-demand conditions, using a model dye. AMF-triggered release was tested from Ti-6Al-4V implant reservoirs.

Results: Two formulations were identified: a non-SPION (20PF127/3SA/CaCl2) hydrogel and a SPION-loaded (20PF127/3SA/CaCl2/SPIONs) hydrogel. Both demonstrated significant improvements over the pure 20PF127 control. SA and CaCl₂ incorporation reduced the gel-sol transition temperature from 78 °C to 55 °C in the non-SPION and to 52 °C in the SPION-loaded formulations, while enhancing structural stability for up to 7 days under physiological conditions. Also, the SPION-loaded hydrogel retained the dye for up to 4 hours longer, thus reducing early cumulative release by approximately 2-fold compared to 20PF127. Furthermore, on-demand release testing with the non-SPION formulation revealed three distinct AMF-triggered profiles, enabling full dye release within 2 hours, matching the total release typically achieved through passive diffusion only after 24 to 48 hours.

Discussion and conclusions: The SPION-loaded hydrogel demonstrated superior passive release suppression and similar hydrogel stability to the non-SPION variant, although under the tested conditions, it did not achieve substantial on-demand release. In parallel, the non-SPION formulation exhibited on-demand release when integrated with titanium implants, leveraging implant-assisted heating for controlled delivery. Together, these findings establish a proof-of-concept hydrogel platform for localized, externally controlled drug delivery in orthopedics.

Background: Commercially available upper limb prostheses for playing guitar require professional assistance for proper fitting and usage. For people who lack this opportunity, alternatives are offered as research models or open-source models. However, adjustable models still require fitting assistance while parameter adjustment is extremely limited. This limits the user’s ability to play more complex music.

Goal: This project proposes the design of a low-cost passive adjustable 3D printed upper limb prosthesis for people with no access to professional prosthetic assistance.

Methods: Both design and evaluation methods were applied. Regarding design, early concepts were designed and selected using a Morphological table and Harris profile, applying rapid prototyping for initial comparison. Regarding evaluation, a parameter measurement and a device functionality test with users with and without upper limb differences were performed.

Results: The final model was successfully printed using Fused Deposition Modeling. The model was evaluated via parameters measurements and a user device functionality test. Results showed that the device allowed the user to put the elbow as a reference point to aid mental mapping of the prosthesis. Speed and accuracy measured during the test suggest a positive outcome for end users.

Conclusion: This design presents an accessible and reliable solution for users with upper limb differences who want to improve their guitar playing skills without the need of professional assistance.

Olfactory research shows a link between olfaction and neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. To study these neural mechanisms, functional Magnetic Resonance Imaging (fMRI) together with flow olfactometry is employed. This study evaluated two MRI-compatible flow olfactometer architectures; the classic air-dilution Lorig layout and a continuous flow vacuum-switch architecture, both built from the same modular base hardware. Both systems were benchmarked head-to-head under identical MRI constraints. Key performance metrics included temporal stimulus precision, stimulus shape, achievable odor vapor concentration range, cross-contamination, airflow stability at the participant interface and MRI compatibility. Air carrier flow rate was varied between 1–10 L/min, delivery tube length between 1–9m, and air dilution ratios between 2.5–90%. For the concentration measurements, undiluted isoamyl acetate was used in combination with a photo-ionization detector. The results show that the vacuum-switch cut stimulus
onset latency by 35–60% and kept it below 500ms with 9m tubing, producing the flattest square stimulus pulses and reducing residual odor to below 1.6% of the primary response. These gains came at the cost of brief flow rate dips of approximately 70% below target during valve transitions and a 20–35% lower maximum odor vapor concentration. The Lorig system delivered higher peaks and steadier flow but showed longer, tube length dependent latency and stronger cross-contamination of approximately 4%. Neither configuration reduced temporal signal-to-noise ratio (tSNR) for fMRI measurements. Together, the results provide quantitative trade-offs that allow researchers to match olfactometer design to the specific timing, intensity and comfort requirements of future olfactory fMRI studies, ultimately assisting research in uncovering the underlying neural mechanisms of human olfaction.

Application of compliant mechanisms in mechanical watches is a cutting edge technique in the world of horology. Flexous Mechanisms BV is leading the charge with the development of the silicon escapement, a monolithic design capable of oscillating at 40 Hertz (10 times faster than traditional escapements). Integration of this technology into a mechanical chronograph is a goal for Flexous, however silicon escapements are more susceptible than traditional escapements to disruption from both internal and external factors. A major internal factor to overcome is the drop in torque delivered to the escapement while the stopwatch of the chronograph is in use. This drop in torque results in significant accuracy loss and potential failure in chronographs featuring a silicon escapement. Addressing this phenomenon is critical for improving torque control and enabling the use of silicon escapements in mechanical chronographs. This thesis explores mechanical methods for constant torque delivery to the escapement, leading to the development of a compliant iris mechanism capable of modulating the effective diameter of a watch barrel to control torque output. Two diameter-torque relationship experiments were conducted: one with a large scale model and inserts for accessible testing, and a second at real scale with inserts designed for an actual watch barrel to confirm findings at large scale. Results showed that the large scale and real scale systems exhibited the same quadratic diameter-torque trends, though of opposite sign attributed to different working mechanisms in friction force creation between the mainsprings. The scaled-up model was further used to evaluate the effect that the number of flexures has on consistency of torque delivery. Flexure count and geometry were found to affect torque smoothness, suggesting a topic for future optimization. While scaled-up fabrication of the complaint iris was limited to 3D prints and adhesive, future designs may employ dual-side Deep Reactive Ion Etching (DRIE) on silicon wafers for monolithic construction. These findings contribute to the design of mechanically integrated torque management systems for chronographs, enabling more versatility in the application of silicon escapements.

Miniaturizing needle diameter has improved patient comfort, reduced tissue damage, and lowered infection risk; however, it also increases the risk of buckling. In nature, certain wasp species have evolved slender, buckling-resistant organs known as ovipositors, which have inspired the development of bio-inspired medical needles. Despite their potential, the needle segments of ovipositor-inspired needles often suffer from high slip in ex vivo tissue. We hypothesize this is mainly due to connective tissue layers causing reciprocating segments to elastically deform tissue without cutting it, preventing needle propagation. To address this challenge, we established design requirements for a needle system capable of adapting to varying tissue stiffness and toughness while minimizing slip in layered tissues. Three functions were defined: transmission, stroke adjustment, and connective tissue perforation. Solutions to each were developed and integrated into concept designs. Among these, the Planar Cam Design emerged as most promising. It features a translationally symmetric cam transmission, a variable-length bar linkage for stroke adjustment, and a vibrating needle for perforating connective tissue layers. The design was fabricated and tested through two experiments: the perforation and stroke adjustment experiments, aimed at evaluating the effectiveness of the vibrating needle and the stroke control mechanism, respectively. Results from the perforation experiment suggest vibration does not significantly improve performance in layered phantom tissues. In contrast, the stroke adjustment experiment indicates that optimal stroke length varies with tissue stiffness, validating the utility of the mechanism. These findings bring ovipositor-inspired needle designs a step closer to practical clinical implementation.

This thesis presents the development and validation of an automatic instrument shaft exchange system for the AdLap robotic surgery platform. The system enables robotic surgical modular instrument shafts to be exchanged automatically without human contact, reducing staff workload and minimizing contamination risk during minimally invasive surgery. A prototype instrument shaft exchange system capable of holding six SATA instrument shafts was successfully designed, manufactured \& tested for the AdLap robotic system. The design emphasizes modularity and quick disassembly, allowing easy cleaning, sterilization, and maintenance while maintaining a compact and robust structure. A ten times repeated functional test without user interaction demonstrated reliable performance, user safety, and tolerance to minor alignment deviations. The mean time for a complete instrument shaft exchange was 84 s (SD = 10 s). Future work will aim to improve system automation and alignment efficiency, as well as develop strategies to autonomously guide the instrument shaft back through the trocar after exchange. These advancements will contribute to smoother, faster, and more reliable operation in clinical environments. Overall, the developed system marks a substantial step towards fully automated robotic modular instrument handling.

Thromboembolic conditions are a leading global cause of mortality and a major cause of disability. Throughout the years mechanical thrombectomy has become a preferred method of treatment over thrombolysis. Mechanical thrombectomy devices utilize either aspiration or various methods of grasping to remove blood clots. Although a variety of MT devices are now in clinical use they all face some trade-offs depending on the removal method they use. This study proposes a novel thrombectomy device. The design implements a strategy of simultaneously gripping the clot and expanding the vessel lumen in order to reduce friction while advancing along the clot’s length in incremental steps. The prototype has been evaluated in a custom-made experimental setup using phantom vessels and thrombi analogs. The proof-of-concept experiments have shown that the device can successfully remove thrombi. The study shows promising results for this new kind of device and can be a foundation for future research into applying similar removal strategies in thrombectomy.

Most early revisions in total hip arthroplasty (THA) are caused by dislocations. It has been established that surgeon experience is a major component in the need for revision surgeries. Currently, no standardised protocol for intraoperative soft tissue tension assessment exists. Furthermore, orthopaedic surgeons do not have a method of preoperative validation of trial implant configurations. To address this problem, the design of a physical simulator of the hip joint with muscle force and strain sensors is proposed, mostly made of widely available materials, manufactured using fusion deposition modeling (FDM) technology. The goal is to create a training tool for orthopaedic surgeons which will reduce the number of revision operations caused by poor hip balance. In addition, the simulator could be used to review the effects of varying implant geometries, which may reduce operation times. The simulator is hypothesised to have a similar joint balance to an in vivo hip, where an increased femoral offset will result in increased tension around the joint. In addition, the increased femoral offset is hypothesised to cause an increased external rotation moment and angle required for subluxation.

A scaling model based on anatomical data is constructed, and an additively manufactured shape is designed which mimics the tensile characteristic of muscle tissue. Sensors are added to almost each phantom muscle, to actively monitor the subjected tension and strain. The simulator is then tested by orthopaedic surgeons, performing two of their preferred movements for hip stability assessment, namely a traction and external rotation test, using three different implant configurations with varying femoral offsets. The muscle strains at the point of subluxation are reported. This experiment is then repeated, but not executed by a specialist, while using an additional implant configuration. During this second traction test, the total traction force at the foot was also measured. During the second external rotation test, the angle and moment required for subluxation were also measured at the foot.

The experiments yielded promising results. Muscle strains were recorded during the traction test for the gluteus maximus, minimus and piriformis which ranged from maxima of 10% to 26% at subluxation. For these muscles, the recorded force and strain were significantly higher (P ≤ 0.05) for the highest femoral offset compared to the lowest offset. During the external rotation test, the gluteus medius and minimus were maximally strained from 12% to 23%, while showing significantly higher force and strain for the highest offset configuration compared to the lowest offset. An increased femoral offset did cause increased tension in the joint, suggesting that the first hypothesis may be valid. In addition, the surgeons were able to correctly answer if there had been an increase or decrease in femoral offset without knowing the current implant configuration. They were enthusiastic about the potential of the simulator as a training tool, both for surgeons becoming more acquainted with the stability assessment movements and as a general method of understanding the mechanics of the hip joint, specifically how an implant configuration can influence these mechanics. This experiment was followed by an experiment where the same movements were performed, but not by a specialist...

This research evaluates granulator performance at GreenCycl B.V., focusing on particle breakage factors like size and material properties. It uses the discrete element method (DEM) and Tavares' breakage model for simulations. The granulator's geometry is modeled in SolidWorks and imported into EDEM.

Key research question: "How to improve granulating performance at GreenCycl B.V.?" Four geometries (Long Axis - 2 Cutting Blades, Long Axis - 3 Cutting Blades, Short Axis - 2 Cutting Blades, Short Axis - 3 Cutting Blades) are tested, with the Short Axis - 3 Cutting Blades being the most productive.

Further analysis of rotation speed and filling technique shows high rotation speed and simultaneous filling yield the best results, despite higher power consumption. The study provides insights for optimizing granulator performance to maximize productivity and efficiency at GreenCycl B.V.

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.

The availability of laparoscopy in low-income settings has been limited based on the requirements that have to be met to perform this type of abdominal surgery. At the same time, these regions and countries could stand to gain the most from it based on quicker recovery times and a lower chance of infections. Attempts have been made to solve this inaccessibility by minimizing the required components to perform this type of surgery at a substantially lower cost. None of these projects have resulted in a laparoscope that can compete with commercial laparoscopes regarding resolution, image quality, and critical design features such as viewing angle. Based on these shortcomings, this study aims to design a sub-500-dollar modular laparoscope for gas and gasless laparoscopy that adheres to state-of-the-art image quality and design features. The laparoscopes are designed following the 'Roadmap for Design of Surgical Equipment for Safe Surgery Worldwide”. Based on the roadmap requirements regarding the needs of patients, end-users, and stakeholders, were acquired focusing on cost, robustness, and reusability. Following the design process, two intermediate prototypes were developed, which were evaluated based on function and image quality by a laparoscopic surgeon to validate the requirements and receive design feedback. They resulted in a modular laparoscope that connects with USB to a laptop, which shares the image sensor, light source, electronics, and handle between the laparoscope for gas and gasless laparoscopy. The gasless laparoscope employs a flexible chip-on-the-tip design that can be straightened for entry through a trocar and released to set the tip angle at 30 degrees. The gasless laparoscope does not have to comply with the trocar and can enter straight through the abdominal entry point. Resulting in a chip-on-the-tip design, which is statically bent at an angle of 30 degrees. To validate the design, a laparoscopic surgeon evaluated the function and image quality, and additional tests were performed to validate the thermal and reprocessing capability. The study resulted in a modular sub-500-dollar laparoscope for gas and gasless laparoscopy, which shows great potential but requires future work to be certified and production-ready.

Minimally invasive surgery has several benefits over open surgery, including a decrease in complication risk, pain and recovery time, but requires higher dexterity and better navigation abilities. Devices that are capable of follow-the-leader motion could offer these navigation abilities, but are difficult to miniaturise without restricting the possible paths in complexity. In this study, a novel follow-the-leader device is presented. The needle consists of seven precurved needle segments that are placed parallel to each other in one shaft. By substituting the needle segments of increasing length in a cyclic fashion, motion along a curved path is enabled, while limiting the maximum outer diameter to 1.6 mm. Control of the needle is done manually, by following an intuitive route with a stylus. The needle tip was evaluated in both air and gelatine, exhibiting maximum targeting errors of 3.4 mm in air and 4.0 mm in gelatine. The maximum footprint width in air was measured to be 10.6 mm. The presented device demonstrates the potential of the new follow-the-leader principle for minimally invasive surgeries.