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.

Background: Bilateral tubal ligation (BTL) is the most common method of contraception worldwide because it is safe and effective. However, its accessibility remains unequal among women in rural India, in part due to a lack of laparoscopic equipment. Rural hospitals therefore resort to gas insufflation-less laparoscopic surgery (GILLS) because it requires less complex equipment. The pneumoperitoneum is replaced by an abdominal wall lift (AWL) device, but these devices suffer from limitations concerning visibility and working space.
Methods: Initiated by the identified medical needs in rural India, a novel AWL device with an integrated imaging system is designed based on methods from literature and input from local end-users. It is a stainless steel hollow circular hook housing an LED lighting system and a 5 MP camera module. It can be connected to any laptop with a USB-A port. The device substitutes for both the traditional AWL device and currently used laparoscopes. The design is exemplified by a fully functional aluminium prototype used for verification and validation.
Results: The selected camera module is the key technology of this design because it provides state-of-the-art imaging at an unmatched price point. The lighting system used for the prototype does not provide enough light, has an asymmetric illumination distribution, and generates too much heat. A structural strength test showed that the strength of the prototype exceeds the material-adjusted design load by 30%. Furthermore, the prototype is cost-effective, lightweight, compatible with current AWL systems, and has limited waterproofness. User tests with an expert rural surgeon confirmed that this design has the potential to improve surgical outcomes of BTL and other procedures, and can increase access to specialized medical care in rural India.
Conclusions: It is strongly recommended to continue the development of this AWL device. The focus points should be the shape and size of the loop (and related cost-effective production techniques), a new lighting system, and the waterproofness of the device. Collaboration with rural surgeons and local biomedical engineers is crucial for context-driven development and implementation.

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.

In up to 39% of reduced distal radius fractures, re-displacement of the fracture occurs in the cast. In most cases, the cast becomes too loose as soft tissue swelling decreases over time and the cast no longer provides sufficient support to keep the fracture reduced. This issue could be addressed by introducing a smart memory cast, a cast that would employ soft polymer foam to relieve stress concentration while providing the required support stiffness to maintain the reduction throughout the whole cast treatment period. Soft polymer foams are characterised by a plateau phase in which the pressure does not increase as the material is compressed. The concept is tested by placing a soft polyurethane foam between an artificial arm that mimics soft tissue swelling and a synthetic cast. The pressure in the smart memory cast is measured by thin film pressure sensors. The average pressure in the smart memory cast was 15.4 mmHg and was reduced by 47.8% compared to the average pressure measured, 29.5 mmHg, in a traditional cast. The pressure in the smart memory cast remained under 25.0 mmHg which was set as a threshold value that could lead to a compartment syndrome. In contrast with the traditional cast where the pressure kept increasing above the threshold value as the artificial arm kept swelling, in the smart memory cast the pressure plateaued. The results from this study show that by introducing a filler material with non-linear elastic properties in a synthetic cast, the pressure concentration is reduced compared to a traditional cast and the pressure plateaus as soft tissue swelling increases.

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.

Distal cement plug removal in total hip arthroplasty revision is a time-consuming and technically challenging procedure. There is a risk of perforating the femur while drilling in the cement plug. This risk increases when the orientation of the prosthesis tip is excentric. The aim of this study was to design a reusable drill guide that facilitates centric drilling in the cement plug and to evaluate this design. The extremity of the drill guide contains two centralizers. Activation of the centralizers results in the centralization of the drill guide in the femur. A set of requirements was defined for the drill guide. To check if the drill guide meets these requirements, different tests were performed. The centralizers were tested in a fatigue test and a radial force test. The usability and functionality of the drill guide were tested in a simulation of the cement plug removal procedure performed by an orthopaedic surgeon. In this simulation was a cement plug in a bone sample drilled in three different conditions. The first condition was without the drill guide. The second condition was with the drill guide by which the handle was kept pressed during the drilling. The third condition was with the drill guide but the handle was released after activation. Furthermore, the disassembly and assembly of the drill guide were tested by five inexperienced test subjects, and the cleaning and sterilization of the drill guide were discussed with experts. This study's results show that the drill guide prototype meets the requirements. The centralizers could be activated ten times without breaking and will not apply a force on the bone that exceeds the yield stress of cortical bone. The absolute deviation of the position of the drilled hole from the centre of the cement plug was significantly lower in the tests with the drill guide compared to the tests without the drill guide. The same test showed that the generated temperature by the drill guide will not cause bone necrosis. Furthermore, the (dis)assembly of the drill guide was performed in less than 110 s. However, the drill guide would benefit from some design adjustments and further testing, such as testing the durability after multiple sterilization cycles. When this is included in the design, the drill guide could be a valuable addition to the standard tools in THA revision.

Prostate cancer is the second most frequently diagnosed cancer in men. A minimal invasive treatment for prostate cancer is transperineal laser ablation (TPLA), which involves inserting a needle containing a laser fibre into the prostate to induce local cell death. The ovipositor of the parasitoid wasp offers a solution to challenges in TPLA, as the wasp can penetrate substrates with zero net external force, minimising the buckling risk and tissue damage. This paper presents the WASP, a design and prototype of a manually actuated needle for TPLA. The actuation mechanism of the WASP transfers a torque while allowing a low-friction translation in the positive y-direction, enabling the needle to travel through stationary tissue. An integrated cam mechanism allows repetitive motion of the needle rods actuated by a single rotation of the urologist. Evaluation of the WASP showed successful travelling through gelatin concentrations up to 15 wt%, a stiffness comparable to human tissue. The WASP generated a small net push force (Fpush = 0.18 N) and cannot be considered fully self-propelling. Nonetheless, the net push force is notably reduced compared to manual needle insertion and effectively prevents buckling. A performance experiment showed a lower average slip ratio compared to previous studies, which may suggest that a small net push force is beneficial if buckling is prevented. Future steps contain implementing user research and a steering mechanism, to continue innovating minimally invasive surgery for prostate cancer.

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.

The objective of this thesis project is to develop an economically viable design for a titanium total ossicular replacement prosthesis (TORP) that caters to the needs of low- and middle-income countries (LMICs). The author focused on addressing the problem from the manufacturing aspect and two primary approaches, additive manufacturing (AM or 3DP) and metal forming, were selected in the literature review attached in Appendix A. One concept was generated for 3DP, utilizing selective laser melting (SLM) to fabricate a straightforward structure using Ti6Al4V. Additionally, two similar concepts, 2A and 2B, were proposed for metal forming, involving precise metal laser cutting of a two-dimensional piece and subsequent bending to achieve a three-dimensional TORP shape. Concept 2A features a fixed-length shaft, whereas Concept 2B incorporates an adjustable zigzagged shaft, aiming to obviate the need for storing multiple sizes of TORPs. These concepts were manufactured into prototypes and systematically evaluated based on predetermined assessment criteria including affordability, manufacturing process, precision, sound transmission property, and simplicity. After assessment, Concept 1 was omitted from the final solutions due to its high cost and demanding post processing steps. And Concept 2A and 2B were deemed as potential TORP designs for the costs of 3.5 and 0.9 euros, dimensional errors of 2.22 % and 2.33 %, preparation duration of 0 and 5 minutes, and the comparable performances in manufacturing process and sound transmission with the commercial products. In conclusion, the TORP designs produced by precision laser cutting were considered the more cost-effective and accessible solutions for LMICs in need of ossiculoplasty.

Background: The lack of access to electric powered wheelchairs for disabled people in low- and middle-income countries, that suit their rural environments, still remains an issue. Current available electric powered wheelchairs that do adapt to these rural environments are expensive and require complex control algorithms.
Objective: The aim of this research is to analyze the feasibility of an electric powered walking wheelchair with an one-degree-of-freedom closed-chain leg mechanism. The electric powered walking wheelchair should provide a solution for low-cost transportation for human adults with lower and upper extremity impairments in the poor road conditions of low- and middle-income countries. A scaled prototype will be designed, build and evaluated with the purpose that it lays the groundwork for future renditions in a true-scaled electric powered walking wheelchair.
Methods: Design requirements were formulated according to the ISO-7176 standards for wheelchairs and conceptual designs were generated, in which a final concept was selected according to the performance criteria. A final design was build and different tests were executed to evaluate the technical specifications and feasibility of the walking wheelchair.
Results: This resulted in the OctoWalker, an 1:3 scaled eight-legged walking wheelchair with a modified Trotbot leg mechanism, two DC motors, timing belt transmission, joystick control and electronic differential. The OctoWalker was able to walk on flat surfaces; steer to the left and right; climb over curb heights of 50 mm; and climb slopes up to 28° without the need of additional sensors and control features to maintain its stability.
Conclusion: The evaluation showed that a true-scaled OctoWalker would have a larger payload (135 kg), step length (675 mm) and speed (4.75 km/h) than currently existing leg-based electric powered wheelchairs. In future studies, improvements for a true-scaled OctoWalker are required in terms of travel range (2.5 km), wheelchair width (789 mm) and weight (140 kg), in order to achieve similar specifications as current stair-climbing and obstacle avoidance electric powered wheelchairs. Nonetheless, the OctoWalker opens up future opportunities for providing low-cost transportation for disabled people in low- and middle-income countries.

The widespread proliferation of cellular lattices in engineering design has entailed a revolution in the design of lightweight and multifunctional structures. Furthermore, the development of auxetic metamaterials has led to applications in fields ranging from biomedical to civil engineering. However, cellular lattices suffer from the development of localized concentrations of strains during deformation, which lead to sub-optimal mechanical performance. Furthermore, the mechanical properties of cellular lattices are dependent on their macro-scale geometries, limiting their design space. Thus, we seek to both enhance the mechanical properties of lattices by ameliorating strain concentrations and expand the design space of cellular lattices.

In attempting to do so, we can turn to nature. The bio-inspired design motif of the hierarchical arrangement of composite materials has lead to exceptional mechanical characteristics in natural materials. Moreover, morphogenetic processes such as bone remodelling play a vital role in the structural development of natural materials and their hierarchical material arrangement. Motivated by these concepts, we developed an algorithm that optimised the hierarchical material arrangement of hard and soft voxels in an auxetic and non-auxetic unit cell. Our algorithm does so based on a bone remodelling-like approach of strain energy optimisation, whereby elements are transitioned to a hard or soft material based on local strain energy.

Our finite element (FE) simulation results demonstrate the considerable expansion of the range of mechanical properties we can achieve simply by modifying material placement on a micron scale. We also observe clear mitigation of peak strain energies and more homogeneous distributions of strain energy density, which affirm the amelioration of strain concentrations. Furthermore, we were able to increase the stiffnesses of our unit cells without substantially affecting its Poisson’s ratio, disentangling previously interdependent mechanical properties. We further validated our FE simulations by additively manufacturing our optimised unit cells with state-of-the-art voxel-based printing. Both the mechanical properties predicted by our FE simulations and the strain distributions correlated well with digital image correlation recordings, validating our models. Our mechanical testing also revealed the considerable in- creases in ultimate tensile strength of our optimised designs, demonstrating the benefits of hierarchical material arrangement.

To conclude, we demonstrate the efficacy of strain energy-based material optimisation to improve the mechanical properties of unit cells and mitigate strain concentrations. The design paradigms of hierarchical arrangement of composite materials remarkably improved the material space of a unit cell without changing its macro-scale geometry. Findings from this study could enable the optimisation of existing cellular lattices and the development of novel unit cell designs with distinct intrinsic mechanical properties.

Bipolar electrosurgical vessel sealing is commonly used in human and veterinary medicine. This method of vessel sealing is often preferred over traditional suturing or clipping of blood vessels because it comes with the advantages of reducing intraoperative blood loss and operation time. Most bipolar vessel sealers are disposable. The high costs of the devices often lead to unrightful reuse in LMICs, increasing the risk of postoperative infection. Next to that, many existing vessel sealing devices operate using a scissor-like clamp that exerts a larger clamping pressure at the proximal end than at the distal end of the clamp. Studies have shown that an unevenly distributed clamping pressure negatively affects the burst pressure of the seal [1][2][3]. The aim of this thesis is to redesign the conventional bipolar vessel sealer to a reusable version that exerts a uniformly distributed pressure across the clamping surface.
A design goal and a set of design requirements were constructed to clarify the objectives. This was followed by a creative design process which was executed to generate solutions for the problems of disposability and uneven pressure distribution. The concept for reusability was verified by mechanical analysis of forces and by rapid prototyping. For the pressure distribution, three concepts were made and tested for performance during an experiment. A redesign of the conventional bipolar vessel sealer was made in CAD containing the innovations for reusability and the pressure distribution mechanism that performed best.
A mechanism has been designed that allows the closing of the upper jaw to be actuated by forward motion of the blade. This eliminates the need for a separate jaw actuator hence promotes cleanability and reusability. The pressure distribution experiment demonstrated which mechanism performed the best. These innovations together with other design considerations have been incorporated into a CAD model of the redesigned bipolar vessel sealer.
The design goal has been met successfully. All design requirements have been met except for one. The removability of the blade lacks in the redesign because it was hindered by other innovations. A list of recommendations has been made to highlight potential future opportunities and shortcomings.

Stiffness perception in laparoscopic surgery has an important role in achieving appropriate tissue manipulation. The need for haptic feedback to perceive tissue stiffness and the reduce in haptic feedback when using laparoscopic instruments suggest an inability to sufficiently experience stiffness perception during laparoscopic surgeries. Better understanding of the perception of tissue stiffness could contribute to the development of better laparoscopic instruments. A stiffness ranking task has been performed with 16 participants, to study the influence of force transmission ratio, contact area and grasping strategy on the haptic perception of variable tissue stiffness. Using a newly developed set of laparoscopic grasper handles varying in the chosen independent variables, being the force transmission ratio and contact area, the participants performed multiple grasps with each grasper handle on a randomized order of tissue samples with three different stiffness levels and ranked them according to the perceived level of stiffness. Force measurements were done during the task and a survey was conducted afterwards. The results indicate that force transmission ratio and contact area do not influence the haptic perception of variable tissue stiffness. In terms of grasping strategy, a lower force exertion is shown to be desirable for perceiving the variable tissue stiffness, while the amount of grasps per tissue sample have not shown to influence the perception. Future studies with larger sample sizes might indicate a difference between high and low force transmission ratios. It is concluded that future designs of laparoscopic grasper handles might not be restricted in terms of force transmission ratio and contact area requirements when a greater haptic perception is aimed at. More haptic perception of variable tissue stiffness is gained in the surgical domain of applying the appropriate grasping strategies.

Minimally invasive robotic surgery adds benefits to the patients, such as reduced blood loss, less scaring and reduced hospital stay. From the literature research preceding this thesis, some of the major obstacles in robotic surgery are the high costs and limited reusability of the instruments. In order to have more affordable robotic surgery, there is a need for low cost robotics and easily cleanable instruments. The design project presented in this thesis represents a driver interface for robotic control of the SATA instrument and is divided into three detachable subassemblies: a motor unit, a cup interface and a gearbox with angular position feedback. This project also represents an upgrade to an existing design that contains the motors and the gearbox inside a single unit, without any sensorics. Design requirements and goals were establish at the start of the project. Possible solutions were designed in CAD and mapped into a morphological table. Each design obstacle had many possible solutions that were considered before choosing the best suited ones. Two prototypes were build out of aluminium and steel with PEEK bushings and 3D printed outer cases. The range of motion and lateral pulling force of the SATA instrument controlled by these prototypes were tested, together with the assembly-disassembly times and shaft coupling times between the gearbox and motor unit shafts. The experimental results showed very low gearbox exchange times and low coupling times with learning curves that prove the ease of use for new users, all translating into a design that allows fast instrument exchange during surgery. The design requirements were met and physical prototypes built and tested, proving the concept works and is suited for the operating room, heading towards affordable robotic surgery.

Each year, many people die due to non-natural causes of death, such as accidents, suicide, and murder and manslaughter. In these cases it is often necessary to investigate the cause, manner and time of death, which are investigated by forensic pathologists and the Police. To determine the time of death, the post mortem interval (PMI), the time passed shortly after death, should then be determined.
Wilk et al. (2020) developed a new method to determine the early PMI (3 – 72 hours). An input parameter in this method is the Thermal Conductivity Coefficient (k-value) of the textile layers surrounding the deceased. A method to determine the k-value of textile layers at, or around, a crime scene is needed. Therefore, this study aimed to design and develop a Thermal Conductivity (TC) measurement device for textile layers at a crime scene.

A functional decomposition chart of the device and a morphologic overview were created to design a suitable concept which was used for further development of the final prototype. SolidWorks was used to perform heat transfer simulations that were required to make the right design decisions and subsequently a final design and prototype were developed. Tests were performed to assess the performance of the prototype in terms of device configuration, accuracy, precision and measurement time. Furthermore, the effects of moisture content of the sample and sample compression during measurement on the calculated k-value were investigated.

A Guarded Hot Plate (GHP) based prototype was developed: Therminus-K2. This prototype was equipped with a back heater and four guard heaters to ensure one dimensional heat flow from the main heater through the sample towards the cold plate to eliminate other heat flows. Therminus-K2 obtains a precision of < 5% in TC measurements within 30 minutes. A steady-state measurement is achieved within a maximum of 7 minutes. Increasing the moisture content (2 states: dried and wetted) in the sample resulted in an increase in determined k-value (205 – 415 %). However, the uncertainty in sample thickness measurement was high (up to 16.7%) and complicated measurement of the sample compression effect on k-values.

Therminus-K2 delivers precise and fast TC measurements of textile samples: impressive results considering the simple components that were used. The future development of Therminus-K2 should focus on improving sample thickness measurement and improve user friendliness in order to make the device suitable to use in PMI estimation at actual crime scenes.