Sentinel lymph node biopsy (SLNB) is a procedure that is used to determine the stage of disease of melanoma patients and determine further treatment. However, the morbidities accompanied with this procedure are not negligible (e.g., wound infection, lymphoedema and seroma). With the goal reduce the incidence of morbidities, this thesis investigated the possibility of minimally invasive sentinel lymph node biopsy (MISLNB). Preceding this thesis, a literature study was written by the writer of this thesis to examine whether there was already a possible solution for this problem. This literature study showed that there are no off the shelf available solutions for MISLNB. Therefore, three solution with the reduction of comorbidities and the importance of \textit{en bloc} excision at their core were proposed. These solutions were found through literature, patents, and some ingenuity. The solution with the highest probability was selected to develop further. This concept was then subjected to different experiments to determine whether it was viable option for MISLNB. This study also aimed to fill some of the missing data on the material behaviour of lymph nodes (LN), specifically stress-strain behaviour under compression. By using a set of requirements one solution was selected to be the most viable given the available information. This solution was called the Pull-and-Harvest method. This concept uses a vacuum to grip the sentinel lymph node (SLN) and stash it in a tube, hereafter a snare would cut the lymph ducts and blood vessels. This concept scored well mainly due to the low risk of damaging SLN and its simplicity. The next step was to determine whether this concept was a feasible solution to MISLNB. The problem was divided into three subproblems to estimate this feasibility. The first being the force required to separate the SLN from its surrounding tissue. Since no data on this subject was available a simplified model was created to estimate this value based on the stretch of lymph ducts. The second part of this problem was, determining the force required to stash the SLN inside the tubular volume. Finally, the maximal force of two silicon suction cups was determined. From these experiments several conclusions could be drawn: the conical silicon suction cups used in this study are very inefficient (10%) efficiency) for gripping LNs, these suction cups will stash the LNs but probably not with the additional estimated adherence force and the risk of damaging the LN using a vacuum seems to be low. Based on these observations during these experiments possible ways of were suggested and could make the Pull-and-Harvest a viable procedure. Lastly stress-strain behaviour of LNs could be described using an exponential relationship. This thesis outlines the problem of MISLNB and highlights the areas of interest for further research. However, there is more research and development needed to find a definitive solution for MISLNB.

The human brain integrates tactile sensory information from the fingertips to efficiently manipulate objects. Sensory impairments due to neurological disorders, e.g. stroke, largely reduce hand dexterity and the ability to perform daily living activities. Several feedback augmentation techniques have been investigated for rehabilitative purposes with promising outcomes. However, they often require the use of unpractical, expensive, or complex devices. In this work we propose the delivery of vibrotactile feedback based on the Discrete Event-driven Sensory feedback Control (DESC)to promote motor learning in post stroke rehabilitation. For this purpose, we prototyped a novel wearable device, namely the DESC glove. It consisted of a soft glove instrumented with PolyVinylidene Fluoride (PVDF) sensors at the fingertips and eccentric-mass vibration actuators to be worn on the forearm. We proceeded with the characterization of the device, which resulted in promising outcomes.
The DESC glove was tested with ten healthy participants subsequently in a pick and lift timed task. The effects of augmented vibrotactile feedback were assessed comparing it to a baseline, consisting of wearing the device unpowered. The results of this pilot study showed a decrease in the time necessary to perform the task, a reduction in the time delay from load force to grip force activation and a diminishing of the grip force applied on the object, which led to a lower breakage rate in the intervention condition. These promising outcomes encourage further experiments with stroke survivors to validate the effectiveness of the device to improve hand dexterity and promote stroke rehabilitation.

Background: Last decades myoelectric prostheses have become more usable, functional and reliable. Yet, the cost of myoelectric upper limb prostheses are still a hindering factor of widespread usage of the prostheses. In developing countries, where the demand for prostheses is relatively higher, commercial myoelectric prostheses are out of reach for the majority of amputees because of limited financial resources. Low cost myoelectric prostheses with the aim of use in developing countries are not commercially available at this moment.
Objectives: The goal of this study is to develop a functional low cost myoelectric upper limb prosthesis. The developed prosthesis will be tested with standardized and validated test methods, to evaluate if the prosthesis is usable and functional. The Box and Blocks Test (BBT) and the Southampton Hand Assessment Procedure (SHAP) will be used for this purpose.
Results: A low cost myoelectric prosthesis prototype was developed in this study; the MyoGrab Hand. The material cost of the prototype was 99.33 euro. The weight of the prosthesis was 352 g. The maximum pinch force of the hand prosthesis was 54.8 N. The MyoGrab Hand was tested by 20 able-bodied participants with BBT and the SHAP. In a first evaluation with ten participants, the prototype proved its functionality with an average score of 17.0 (± 2.2) with the BBT and an Index of Functionality (IoF) of average 41 (± 8.3) with the SHAP. After optimizing the Arduino code structure, the MyoGrab Hand was evaluated again. Ten able-bodied participants carried out the BBT. The average score on the BBT with the optimized MyoGrab Hand was 18.4 (± 2.4). The result of the BBT in the second evaluation was not significantly better than in the first evaluation (t = -1.3, df = 18, p = 0.21). In a durability experiment, critical failure of the prototype occurred after 16539 cycles of opening and closing of the hand.
Conclusion: The goal of this study, the development of a functional low cost myoelectric prosthesis, has been achieved. The MyoGrab Hand was evaluated with standardized and validated test methods and proved itself functional. This is one of the first studies that was focused on the functionality, usability and durability of a low cost myoelectric prosthesis. The functionality of the MyoGrab Hand does not equal the functionality of commercial myoelectric prostheses, commercial myoelectric prostheses are more functional. The MyoGrab Hand was able to perform most of the activities of daily life (ADL) tasks in the SHAP, however, carrying out these ADL tasks took longer, as compared to commercial prostheses. This study is a first step in the direction of making a functional myoelectric prosthesis available to larger part of the amputee population with limited financial resources. Future research should focus on a lower weight battery solution, waterproof design and testing in a non-clinical setting.

Background: The majority of the amputated population is living in low-resource countries, but only a small minority has access to rehabilitating services. The accessibility of upper limb prostheses in these countries is poor due to limited technical and medical resources. 3D printing is regarded as a promising manufacturing alternative in contrast to the expensive and labour-intense conventional processes. However, the majority of the developed 3D-printed prostheses show weak functionality characteristics and do not meet basic user requirements. The goal of this research is, therefore, to design and evaluate a new body-powered prosthetic device which is fabricated with a 3D printer and easy to assemble, capable of performing high force-transmissions with an appropriate pinch force output, and meets the basic user demands. Methods: An analysis of the widely used conventional prostheses and available 3D printed prostheses has been performed, and as a result, design requirements have been set up. Based on these requirements a prototype has been designed using SOLIDWORKS, and is printed with a FDM printer. Mechanical characteristics have been measured using a test bench, and the functional performance has been evaluated by ten able-bodied subjects using the SHAP and the BBT. These results were finally compared to results of conventional prostheses, as found in the literature. Results: The final prototype of the 3D-Sanhand is presented; the 3D printed Simple to Assemble Natural-looking hand prosthesis. This prosthetic device has a one-degree-of-freedom rotating thumb and is, except for a pressure spring and an elastic rubber band, completely printed with a FDM 3D
printer. The device is capable of performing a 15 N pinch with an actuation force of 24 N, which is lower than the required actuation for conventional prostheses and within the boundaries of fatigue-free use. It has a low mass of 142 gram which is a reduction of over 50% in comparison to the commercially available designs. The opening width of 75 mm is in line with conventional prostheses. The sliding mechanism in the rotation point enables the users to change the initial position of the thumb and to reduce the opening width, to allow all users to pick up objects from different sizes. User tests showed that the prosthesis was capable of picking up a variety of different object shapes and did not encounter difficulties with heavy weights. The main problems were subjected to the smoothness of the finger tips and the impossibility to pick up thin objects from the surface. Conclusion: This thesis describes the design of the first 3D printed hand that can be assembled without any technical and medical knowledge or complex tools and machinery. The hand performs a pinch force high enough to perform activities of daily living under comfortable operational forces, and that is comparable to conventional prostheses on the market. Future research should further investigate what the wear effects of 3D printed materials are on the long-term use, and should propose directions to increase the durability and efficiency of the design.

The project is divided into three sub-assignments: - A future manufacturing context must be envisioned and the most important requirements synthesized. - An implementation of this envisioned manufacturing system must be developed and validated. - An exemplary-product producible by this system must be designed, showcasing the benefits of the envisioned manufacturing method. Envision Following the problem definition and assignment defined in the Introduction phase, the current state of manufacturing and how we got there is analyzed. A future context around a complete product-life-cycle is envisioned. Within this vision both the product as well as the factory are explored. The design tasks were performed in parallel, but they will be described in sequence. First the factory will be discussed: a manufacturing concept is synthesized, the underlying principles are analyzed, and a factory classification is done. Then the exemplary-product will be discussed: the underlying principles of product personalization are explored, and the principles of a product within the developed future context are described. The acquired knowledge gets integrated in a design brief and a list of directing requirements. These form together with the future vision, a starting point to design an actual realization of both product and factory in the phase after the Envision phase. Actualization Following the design brief defined in the Envision phase, the conceptualization of both product and production need to go hand in hand. A realizable future production system must be accompanied by a product that showcases this manufacturing method and the other way around: the personalizable product-family requires a production system that is capable of producing these one-off-products at a high production-capacity. Both design tasks were performed in parallel, but they will be described in sequence in this part of the report. First the exemplary-product will be discussed: the choice, the conceptualization, and the embodiment. Then the Transcended production system will be discussed: the required standardization, the proposed production cluster, conceptualization of the production framework and embodiment of the initial prototype. This prototype can then be used for validation of the propped framework in the phase after the Actualization phase. Validation In the Actualization phase a framework is proposed for the full, so called, pick-and-place on-printing process. This framework should be able to produce the designed computer mouse. And a prototype is developed solving the most important FDM-Cabinet embodiment challenges, resulting in a working system. The goals for this prototype are, firstly to demonstrate an initial framework that is able to produce a personalized consumer electronics product from start to finish at a mass-production output capacity (theoretically). And secondly to validate the pick-and-place on-printing process as a feasible method to produce multi-component parts. The Core Functional Requirements for this prototype are discussed and validated in each of following sub-chapters. The last subchapter validates the Core Functional Requirements for the exemplary-product itself. The research findings will then be used for evaluation in the phase after the Validation phase.

Background: While new prosthetic hands are developed to increase functionality and allow more complex movements, prosthetic wrists are researched less. Although there are wrists available, primarily featuring 1 degree of freedom (DoF), only a few prototype 3 DoF wrists are currently known. These 3 DoF wrists usually have sufficient range of motion (RoM), but they fail in delivering high torques while being lightweight and compact, which can increase chances of rejecting the prosthesis. Objectives: The purpose of this study is to design and evaluate a conceptual 3 DoF wrist that is capable of replicating the RoM of the human wrist while keeping the size and mass as low as possible. Furthermore, the wrist needs to be able to deliver more torque than existing 3 DoF wrists. Results: A functional 3 DoF prototype was created. The design is actively controllable using three motors and pumps but can also adapt to different surroundings if the motors are off. The prototype is capable of a total range of motion of 142° for exion/extension and 90° for ulnar/radial deviation and can provide estimated torques of 4.52 Nm and 7.29 Nm respectively. Pro-/supination was not measured, but can provide a theoretical RoM of 134° and torque of 8.9 Nm. The complete wrist has a length of 150 mm and a diameter of 50 mm at the thickest part, and a mass of 166 g (including fluid). Conclusion: A 3 DoF wrist that is theoretically able to provide more torques than previously researched wrists is successfully designed and tested. The available RoM approaches the required RoM, except for pro-/supination. Future research should primarily focus on measuring the front part of the wrist using higher pressure. The 3D printed pro-/supination part of the wrist should be further researched to improve RoM and remove leakage while pressurized.

Radiofrequency ablation (RFA) is a localized thermalintervention technique with the purpose to destroy small tumours (< 3 cm) byheating the tumour tissue. Due to various challenges with targeting andvisualisation during RFA, the clinical need of steerable needles is present forradiologists. Helwig, B.P. developed a new omnidirectional steerableneedle for this purpose. However, this needle is not yet ready forimplementation in the operation room (OR) because no clinical testing isperformed in vivo. Therefore, the aim of this thesis is to develop a novelneedle guide tool for percutaneous interventions with an omnidirectionalsteerable needle during real-time US-guidance. In order to examine the visibility of the steerable needle,an experimental study has been conducted. The steerable needle has a promisingvisibility in Polyvinyl alcohol and is expected to be well visible duringultrasound guided interventions. The developed needle guide tool is calledUShift and provides both the benefits of needle guided puncturing and free-handpuncturing. Which are for free-hand puncturing: freedom of movement of boththe probe and needle during puncturing and for needle guided puncturing:  a shorter procedure time, reduced needle manipulation and improvedneedle visualisation. A user test is performed to verify how the needle guide isperforming compared to the currently used needle guide while hypothetical usingthe Omnidirectional steerable needle. The difference between the two puncturetechniques is 0,9 seconds, the UShift is 23% faster. In conclusion, thisproject resulted in a novel needle guide tool that can be used in combinationwith the omnidirectional steerable needle during percutaneous interventions.The UShift has great benefits compared to currently used needle guides and istherefore stated as innovative. More gain is to be expected through future researchconcerning production methods, material options, the cost-effectiveness andother application fields of the UShift.

Analyzing the different signaling pathways of cells is key in understanding the basic functions of the cells in all organic systems from algae to humans. Not only do they help solve our questions on how organisms function, they also allow for new cures to be explored. A large variety of these signaling pathways can be influenced by light and can, for example, stimulate or inhibit cell growth. This research thesis introduces a new lab-on-a-chip MEMS device to help with the cell signaling exploration with a focus on optical cell stimulation. From a culture of HeLa cells, the chip is able to separate individual cells into different chambers by means of microfluidics. These microfluidic channels are processed using SU-8 and place each cell above an LED. In total, each chip houses ten LEDs with four different wavelengths ranging from 450 to 850 nm. Each of these LEDs is individually addressable through an Arduino MEGA with a Matlab user interface. After an introduction into cell signaling, the thesis describes how the chip is build up from two silicon wafers and one glass wafer, and explores novel assembly methods like SU-8 wafer bonding and the use of apertures.

embargo

Atherosclerotic plaque rupture is the main cause of acute myocardial infarction and stroke, the two leading causes of death worldwide. Rupture of plaque tissue is a mechanical event, where plaque stress or strain locally exceeds its strength. Biomechanical studies agree with histopathological findings that a large lipid pool and thin fibrous cap overlying the lipid pool increase the likelihood of rupture, by showing increased plaque stresses for these geometries. Another plaque morphological feature that is frequently encountered is calcification. However, its role in the vulnerability of plaques to rupture is not fully understood, and biomechanical modeling studies do not agree on the effect of calcifications on plaque stress. These studies used isotropic material properties for the anisotropic and collagen rich plaque tissue, and generally focused on the effect of calcification on lumen stress or cap stress. However, histopathological findings revealed tissue damage at the interface between calcification and surrounding tissue.

This study investigated stresses and strains at the interface between calcification and fibrous tissue, how these stresses and strains are influenced by local anisotropy of the fibrous tissue and how geometric features of the calcification are related to these metrics. A morphometric study was conducted first, to investigate and categorize different patterns of fiber alignment around the calcifications, and to measure the calcification geometric features including its location in the plaque, its shape and its size. Biomechanical models including the local anisotropic material properties were constructed next, based on the observations and measurements made in the morphometric analysis. Stress and strain metrics were investigated at the calcification boundary, and subsequently related to fiber patterns and calcification geometric features.

Hundred forty five calcifications were segmented and measured in the morphometric analysis, and surrounding fiber alignments were studied. The analysis revealed that four main fiber patterns in the fibrous tissue surrounding calcifications exist: the Attached pattern, Pushed Aside pattern, Encircling pattern and Random pattern. Collagen fibers are attached to the calcification in the Attached pattern, are pushed aside by the calcification in the second pattern, encircle the calcification in the third pattern, and show a disorganized alignment in the Random pattern. The Attached pattern was the most prevalent fiber pattern, and its corresponding calcifications had larger aspect ratios and were on average larger than the other three fiber patterns. Large peak stresses and strains at the calcification boundary were identified in the biomechanical models for the Attached pattern and Pushed Aside pattern, while these metrics showed generally lower peak values for the Encircling pattern and Random pattern. Peak values for all stress and strain metrics were attained at the tip of the calcifications. Multivariate analysis showed that stresses and strains are related to the calcification geometric features; calcification interface stress and strain increased if the calcification was closer to the lumen, had a larger length/width ratio and was larger in size.

Histopathological examination of plaques evidenced damage at the interface between calcification and fibrous tissue, potentially caused by an adverse mechanical state at this boundary. Most studies focused on stresses at the lumen or in the cap however, and this study for the first time specifically investigated stresses and strains at the calcification boundary while simultaneously introducing local fibrous tissue anisotropy in the computational models. Results show that peak stresses and strains can develop at this boundary, which will remain undiscovered if isotropic materials are used. This study was also the first to extensively analyze calcification geometric features and surrounding fiber alignment in relation to these interface stresses and strains. Peak values were found to be dependent on these features and fiber alignment patterns, indicating a relation between these characteristics and mechanical stability of the plaque. The findings of this study further increase the clinical relevance of finite element modeling in rupture risk prediction by showing previously undiscovered peak stress and strain values for interfaces and geometric configurations which already were deemed to be destabilizing in clinical and histopathological studies.

The arrival of highly automated vehicles introduces a new interaction between the vehicle and driver. System limitations during highly automated driving require the driver to be ready to take back control at request.
Previous studies on the take-over process concluded that the driver requires a transition period to stabilize vehicle control after resuming manual control. These studies used traded control to instantaneously transfer control back to the driver, causing an abrupt switch in control authority. Therefore, this study explores Haptic Shared Control as a different transition approach. By varying the level of haptic authority, a smooth connection between automation system and driver can be realized. The aim of this study is to investigate if Haptic Shared Control improves the take-over performance compared to the traded control approach. A total of 30 participants drove two trials in a driving simulator, one for each transition approach. Each trial consisted of 10 take-over scenarios divided into two levels of time-criticality. During autonomous driving the participants were engaged in a secondary task. The take-over performance was assessed based on safety performance, lateral vehicle control, controller performance and subjective measures.
Results showed a significant decrease in the standard deviation of the lateral position evaluated over the mean trajectory per participant for the Haptic Shared Control approach compared to traded control. Haptic Shared Control also showed a significant decrease for the mean lateral obstacle clearance. The analyses on torque conflicts revealed a significant increase for critical take-over maneuver compared to non-critical take-over maneuvers.
This suggests that haptic shared control can assist the driver in stabilizing lateral vehicle control after resuming manual control. On the other hand, the driver is limited in performing a sharp evasive maneuver, and this relationship is discussed. More research is needed on using an adaptable human compatible reference.

The purpose of this project is to design and develop a set of force sensors to measure steering forces applied by an athlete down the ice track. Currently, there is not enough information about instrumentation in skeleton, and to maintain competitive advantages, most of the research remains private and unpublished. Athletes use their shoulders and knees to steer down the track. For this reason, four handmade piezoresistive tactile force sensors were built to measure the force applied by each joint. Each sensor has its own model to convert bits recorded into force. Results showed a difference between applied and calculated forces by each model. However, calculated results followed similar trends compared to the real values of the applied force. In addition, a graphical user interface was created to present the results to the athlete in a simple and easy way to read and understand. It is planned to use a shimmer (an inertial measurement unit) to collect information about accelerations developed on each run. Coupling both measurement systems have to be done during the processing stage. Further work has to be done regarding electronics size and testing the systems in a real run down the track.

The operating room and central sterile supply department (CSSD) are two
resource-intensive healthcare departments. Reducing the environmental and financial impact of these departments is of great importance in the global debate on sustainability. Removing unnecessary items from instrument trays may provide a partial solution. However, improvements to tray compositions are often time-consuming, not permanent and not using the full reduction potential. This research compares different methods of medical instrument tray optimization and combines different aspects to create a new methodology. Three models compared and evaluated objective and subjective instrument use percentages and different suggestions for tray optimizations. New tray compositions, based on objective use rates, were discussed with the medical specialists and attuned to their requirements. The result
was then reviewed by the OR-assistants, before making any final adjustments. This methodology is tested for abdominal instrument trays at the gynaecology department of the Leiden University
Medical Center (LUMC). The new trays were evaluated over a test period and missing items were registered during follow-up. Risks to patient safety as a result of missing individual instruments
and chances of missing instruments for different reduction methods are discussed and quantified. Mean use rates of the designated instrument sets are 28.4% (SD=6.43%) for open surgery (n=16) and 47.6% (SD=8.16%) for minimally invasive procedures (n=12). A 37% reduction of instruments is reached across three abdominal trays by removing unnecessary items. Weight of the tray contents is reduced by 31%. During the evaluation (n=7 procedures), mean instrument use for abdominal procedures increased from 28.4% (SD=6.43%) to 46.47% (SD=10.96%) after tray optimization. A reduction based on use rates with a 10% cut-off or based on the recommendations of the medical specialists, induces an 8.7% or 3.9% chance of missing any instrument during the procedure, respectively. Tray content reductions based on OR-assistant suggestions and objective use rates with a 0% cut-off are safe, but do not utilize the complete reduction potential. Different tray optimization methods were compared. Use rates were measured in the OR and expert recommendations were discussed in group sessions. A combination of objective use rates and subjective expert considerations can lead to a significant reduction of the amount of unnecessary items in the medical instrument cycle without harming patient safety. Group consensus amongst medical specialists suggests the most radical reduction of instruments on the tray, but increases chances of missing instruments during surgery. Recommendations based on use rates have to be supplemented by reduction efforts based on the clustering of equivalent instruments. Future work should focus on ways to scale reduction efforts to an autonomous hospital-wide system and teach optimization models to mimic human expert input. It should also focus on exact measurements in the CSSD to estimate reductions in costs and CO2-footprint reliably.

In the field of prostheses, significant developments have been accomplished so far in low-cost prosthetic limbs using 3D printing technology. However, when it comes to prosthetic hands, 3D printed prosthetic hands are still limited in their grasping ability, such as the adaptability to the shape of an object and a sufficient pinch force level for practical use. The goal of this experimental study is to engineer a bio-inspired surface structure to improve the grip action of prosthetic hands. The low-cost FDM 3D printing technology in combination with the flexible material, Thermoplastic Polyurethane (TPU) 95A, was evaluated for this purpose. 3D printed surface (deformable) patterns were printed on top of a flat, rigid surface. The 3D printed patterns consisted of pillars or lines with varying thickness d, tip thickness D, wavelength λ, and curvatures α that were combined into different patterns. The frictional characteristics of the 3D printed patterns were assessed for nine different test scenarios, i.e. three different loads F_N against three different countersurfaces. Despite the small differences in the static coefficient of friction μ_s of the 3D printed patterns, some consistent trends were found. First, μ_s increases with increasing thickness d. Second, μ_s increases with increasing wavelength λ up to a point in which the decrease of number density of the 3D printed features decreases the overall friction. Third, μ_s increases for pattern curvatures with peaks in the opposite direction, such as wave or circular patterns. Lastly, μ_s decreases under increasing normal load F_N. The surface patterns were tested on the fingertips of a 3D printed prosthetic hand. The fingertips were assessed using the Box and Blocks Test (BBT), in which the pattern with the highest score displayed an ~70% increase in the number of blocks moved, compared to the original rigid fingertip of the 3D printed prosthetic hand in question. Further research and development are essential, especially for the FMD 3D print process of small dimensional printing in combination with flexible materials. Nevertheless, the proposed fingertip pattern demonstrated a first step towards future improvements of the grip action of low-budget 3D printed prosthetic hands using soft fingertip patterns.

Introduction: Recently 3D printing has received an increasing attention on the area of actuators. It can provide design freedom allowing complex geometries, as well as customization, among other benefits. However, there is no research on 3D printing of hydraulic piston-cylinder systems. The aim of this article is to check the feasibility of 3D printing a hydraulic piston-cylinder system, as well as quantifying its performance. Methods: The same design was utilized for different 3D printing processes (Fused Deposition Modelling (FDM), Stereolithography (SLA) and Selective Laser Melting) and materials (Polylactic Acid (PLA), resin and Titanium), in order to be compared with each other and with conventional manufacturing of a system in Aluminum. Also, a second version of each piston-cylinder system was printed to use a reamer on them, to compare the performance between the cylinders with and without reaming. The followed methodology consisted of performing static and dynamic tests for each of the actuators. The output of the static test was the maximum fluid pressure that the system can handle. With the dynamic test a more realistic situation could be tested, from which the friction could be deducted and its results could be compared to the theoretically calculated data. Results: The results showed that the best performing 3D printed option was the reamed SLA resin version, reaching pressures of at least 4~MPa, with a dynamic friction force of 6.6~N, a stick-slip friction force of 9.9~N and a weight of 28~g. These features led to a force-to-weight ratio of 2928, only surpassed by the lighter FDM printed PLA actuator, reaching a value of 3565, but with higher friction forces. Conclusion: The conducted research means a first step towards the 3D printing of hydraulic piston-cylinder systems, demonstrating that it is possible to reach high pressures without leakage. The features that additive manufacturing offers, such as lighter and customized geometries in one assembly step, can benefit application fields where hydraulic piston-cylinders are used, such as prosthetic devices.

At present, commercially available wearable sensors are only capable of tracking an individual’s physical activities and vital signs (such as heart rate). However, these devices fail to provide insight into fatigue itself. Fatigue is a broad term with many meanings. Fatigue in this paper refers to physiological changes where the muscle becomes fatigued due to increased lactate concentration during high physical activities. Real-time measurements of thermal sweat out of the eccrine glands could enable such insight because it contains physiologically and metabolically rich information that can be retrieved non-invasively. Thermal sweat that secretes out of the eccrine glands contains multiple inorganic constituents such as salt and potassium, nitrogen compounds such as ammonia and urea, and sugars such as glucose and lactate. Most literature agrees that ammonia is a potential constituent for determining the state of muscular fatigue. Different methods were proposed for real-time ammonia monitoring. Out of all these methods, a concept was designed using MOS sensors which measures ammonia concentration in a gas phase. This design was tested by letting participants perform an incremental cycling exercise up to the point while monitoring the ammonia concentration, temperature, humidity, and respiratory exchange ratio to validate whether the sensor is able to determine fatigue. The results are inconclusive whether it is able to determine fatigue through real-time ammonia monitoring.

Lifting an object by capillary forces is mostly done with a single liquid bridge which connects the target object to a probe. In this work the potential of capillary forces for soft-tissue manipulation is investigated; not only a single liquid bridge is used, but multiple bridges as well since capillary forces can be enhanced by contact splitting. Specifically, laparoscopic bowel surgery was chosen, because with current instruments it remains difficult to atraumatically grip soft delicate tissues.

Three 30 by 30 mm grippers were cast from PDMS (1:10 weight ratio curing agent to base) with pillars of diameter 2, 1 and 0.5 mm, named D2, D1 and D05 respectively. The ratio of pillar area to total gripper area is 0.6. The pillar structures and a flat reference sample were wetted with demi water and placed on the substrate (glass and 15 wt.% gelatin as tissue phantom). A preload is applied to attach the gripper to the connector and both are retracted at 0.1 mm/s to measure the adhesion. From the camera footage of the measurements on glass was confirmed for D1 and D2 that capillary forces were measured. The best performing pillar structure was D1 with adhesion values between 1.3 – 3.4 kPa, but it did not outmatch the flat samples’ adhesion: 2.2 – 3.1 kPa. On gelatin, the evidence for measuring capillary forces was not conclusive. The mean adhesion of all geometries on gelatin was 0.8 kPa and there was no clear effect of the different pillar diameters on the measured adhesion values.

From these results it is concluded that capillary forces should not be used as the main method to lift tissue, but rather to complement other gripping methods such as suction.

A sit-snowboard is a weight supporting mechanism that allows people with lower extremity impairments to perform the sport of snowboarding. Comfort and control of the Twinrider (the only sit-snowboard on the market) are insufficient for advanced riders who reach higher speeds and ride more bumpy slopes. The goal of this study is to design a sit-snowboarding mechanism that provides sufficient comfort and control for advanced users.

In the new mechanism design (Snowcruiser), vertical suspension is added between the seat and the board using two mountain bike forks. Independent compression of the forks, nose/tail translation of the seat and board flex are allowed. These alterations prevent control interference, visional and vibrational discomfort due to seat tilt, vibrations or shocks on the seat. A continuous interaction of the snowboard with the surface though board flexion and less vibrations on the board also improves control.

With a quantitative test the performance of the new design is evaluated by a straight descent from a bumpy, artificial slope. The prototype carried a dummy weight and the descent is guided by a skier. Using four accelerometers of which two were placed on the board and two on the seat, accelerations were measured. To assess the severity of these vibrations and shocks the standard BS 6841 is used. Vibration Dose Values (VDVs) for the board and the seat are determined after weighting the accelerations to the frequency and direction as described in the standard. Seat tilt and contactless distance were determined using data from high speed cameras. Setting each combination of maximum and minimum height, compression and rebound speed resulted in eight Snowcruiser models. With analysis of the variables, speed dependency is checked and an insight is gained on the behavior of the different combinations of settings. Also a qualitative test is performed in which two riders actually sit in the prototype and slide over hills while turns are made.

The measurements show that the VDVs on the seat are lower for all Snowcruiser models than for the Twinrider, indicating less discomfort. The riders of the qualitative test confirmed this by experiencing a smooth run: No shock is felt when landing after a hill. The Seat Effective Amplitude Transmissibility (S.E.A.T.) is not lower for the Snowcruiser than for the Twinrider, so vibration isolation is not more efficient for the Snowcruiser. However, the Snowcruiser shows reduced accelerations on the board. The Snowcruiser is able to keep the seat horizontal for small inclines. The qualitative test shows that more board flexion is possible. The variable of contactless distance is strongly depending on riding speed, and therefore not a useful variable in this study.

Both tests show that comfort and control are improved for the Snowcruiser and that the goal is achieved. A height of 500mm, maximum compression and fast rebound form the most promising combination of settings. The measurement method presented in this study is a valid method for performance evaluation of comfort and control for a sit-snowboard, using the variables VDV and seat tilt.

Background: When a suspicious lesion is detected, a thorough examination is essential for the diagnostics of the lesion. Information about the nature and character of the lesion is crucial for the determination of the disease and an appropriate corresponding treatment plan. Taking a biopsy plays an important role in this examination. A biopsy is the removal of a tissue sample from a living organism. The aim of the biopsy is to provide a sufficient and representative part of a lesion, which will enable a thorough examination. Unfortunately,
the diagnostics of a biopsy is not always as accurate as desired. Core-needle biopsy is a commonly used minimally invasive biopsy technique. This technique uses a needle, with a varying size between 1.3mm to 2.1 mm, to cut away a tissue sample from a lesion. Biopsies taken with core-needle instruments do not
always represent the lesion sufficiently. It is often hard to determine the exact lesion site, and to know if the needle has indeed taken a biopsy from the lesion. To prevent non-diagnostic results from the biopsy, multiple samples should be taken from the lesion site. Common core-needle methods currently obtain a single biopsy sample per insertion. As multiple specimens must be obtained, multiple insertions of the biopsy instrument are required. The aim of this research is to design a single-insertion multiple specimen biopsy instrument.
This design will be developed and evaluated on its performance and functionality.
Methods: A list of requirements was setup to determine the conditions which comprise the design. Next to the requirements, a functional analysis was carried out which divided the functions of the design into three main functions. A, the insertion of the device into the lesion, B, the actions required to obtain a multitude of samples, and C, the retraction of the instrument from the body. The actions to obtain a multitude of samples, are subdivided into five actions: (1) the instrument must collect a tissue sample, and (2) enclose this tissue
sample into a container. (3) This container must be transported through the instrument. And subsequently stored inside the instrument, (4). Finally, (5) the instrument must be reloaded. This sequence of actions can be repeated until a number of specimens have been obtained. Using these five actions as a lead of the design process, conceptual designs were created. During the design process inspiration was found in firearms. The storing of bullets and reloading mechanisms found in guns could help find solutions to the storing and
reloading functions of the biopsy instrument. For each action a conceptual design is developed, and finally these five conceptual designs are combined and elaborated, resulting into one final design. A prototype of the final design was developed and evaluated. The prototype was validated on three different aspects: the ability to obtain multiple biopsy samples through a single insertion, the ability to use the prototype in accordance to the intended use, and a comparison between the prototype and an existing biopsy instrument in terms of
procedure duration. For each of these aspects the prototype was validated in three different proof of concept experiments.
Results: The prototype proved to successfully be able to take a multitude of biopsy specimens through a single insertion. Next to this initial evaluation, the intended use of the instrument is also successfully performed by the prototype. The last evaluation of the prototype, has shown that the procedure time of the
prototype to take a multitude of samples is longer than the procedure time to take a multitude of samples using and existing biopsy instrument (TruCore II). The prototype took 5 minutes and 7 seconds, whereas the existing biopsy instrument took 3 minutes and 50 seconds to obtain multiple tissue samples.
Discussion and Conclusion: The fabricated prototype has proven that it is able to take multiple tissue samples through a single insertion. This multitude of samples can be used to improve the diagnosis accuracy of core-needle biopsy. The functionality of the prototype is in accordance to the intended use. This
intended use provides an indication of the possibilities of use of the prototype. The procedure time of the prototype can be decreased by further improving the usability of the design. Future research can focus on a more elaborate evaluation on the accuracy of the instrument. Furthermore, future work can be carried out
on decreasing the instrument length of the current design. Another research can be done on possible ways to implement a semi-, or even a fully-automatic reloading and transportation mechanism on the now manual operable instrument. With these additional future improvements, this initial proof of concept prototype has the potential to become a fully functioning biopsy instrument.

During endonasal pituitary surgery - an approach of skull base surgery - long slender instruments are inserted through the nose of the patient, in order to remove a pituitary lesion. One of the instruments which is repeatedly used is the surgical punch, which is able to remove pieces of bone in order to create access to the lesion. The drawback of the currently used surgical punches is twofold: first of all, they do not allow for rotation of the tip relative to the handle orientation in order to align the tip properly to the bone to be cut. Furthermore, the successive introduction and extraction of the instrument from the operational area after each cut, increases the risk of introducing bacteria and slows down the procedure.
A novel surgical punch was designed and developed called NeuroPunch. Throughout the course of this study, a human-centered design approach combined with a systematic engineering process was followed leading to several conceptual solutions for different functional parts of the NeuroPunch. By combining these conceptual solutions, a design was set for a first functional prototype including an ergonomic handle, a mechanism for the storage of punched bone pieces, and a mechanism for rotating the tip relative to the handle orientation.
A first evaluation of the functional 1:1 scale prototype with end users shows positive results indicating that the NeuroPunch might be a proper replacement for the currently used punches in endonasal pituitary surgery. Several iterative steps are required to produce a fully functional prototype of the NeuroPunch which can be evaluated in a preclinical setting (e.g. cadaver study). The NeuroPunch shows much potential to be used for other surgeries as well, and it is demonstrated that the NeuroPunch will enable a safer and more comfortable endonasal pituitary surgery while potentially reducing operating time.