The 3D-digitisation of precious cultural heritage artifacts is highly important for historical preservation purposes. Doing so can help mitigate against events such as tourism damage, natural disasters, and war. It also enables access to three-dimensional data for researchers of all disciplines all around the globe to study these artifacts at the same time. Furthermore, future generations can benefit from an online database of archaeological artifacts for educational purposes. Several high-end solutions are available. However, the cost to purchase or leasing can be too substantial for heritage institutions that often run on small budgets. Therefore, there is a need for cost-effective solutions to create high-quality 3D-images of archaeological artifacts. This thesis focuses on the 3D-imaging of small archaeological artifacts. When creating 3D-images of the artifacts, it is important to capture the texture details and preserve color information correctly. An extensive literature study was done on the existing 3D-imaging technologies and systems. It was concluded that photogrammetry is the most suitable technology available to create 3D-images of small archaeological artifacts. Photogrammetric systems have been studied for their ability to create high-quality 3D-images. Literature states that the quality of the 3D-images created with photogrammetric 3D-imaging systems suffers from a small depth of field. By the nature of optics, this small depth of field occurs when photographing an object from a close distance. This thesis provides the design and validation of a cost-effective photogrammetric 3D-imaging system for small archaeological artifacts. This system is optimized for the depth of field and is able to successfully create high-quality 3D-images with highly detailed textures and color information. This design overcomes the small depth of field limitations by implementing focus stacking. The system's most intensive task, the acquisition of photographs, has been automated, and a working compact system has been created. ... Read more

In orthopaedic and dental surgery, bone grafts are used by surgeons as substitutes for the patient’s own bone. A bone graft provides support to the skeletal structure and stimulates the ingrowth of new bone. There is a growing demand for bone grafts due to an increasing world population and an ageing demographic. Tissue banks produce bone grafts originating from either human bone or animal bone. Bone grafts have been investigated profoundly. However, there is no literature that provides a standard protocol for the production process of bone grafts. The current production processes for bone grafts are inefficient because of many manual interferences by humans and consist of many complex production steps. This thesis aims to provide a bone processing protocol and investigates the first steps to developing an automated production line for bone processing. The automated production line must transform fresh donor bone to an end-product that is a clean and sterile allograft consisting of bone mineral and collagen. There is a hiatus in the knowledge about processing bone with multiple ultrasonic frequencies. This thesis provides new insights in processing bone with ultrasonic frequencies. Acoustic cavitation is produced by ultrasound and is used as a mechanical cleaning force. The literature review suggested that combining ultrasound frequencies is beneficial for cleaning. Low ultrasonic frequencies of 35 kHz have a better potential in removing large particles such as blood clots. High frequencies of 130 kHz are better for cleaning small particles such as small lipids and virus particles. This thesis researches the combination of multiple ultrasonic frequencies which should lead to optimal cleaning results. This thesis solves these research goals through an iterative process based on an extensive literature review, numerical modelling, testing and analysing cleaning procedures for bone samples. Human femoral heads were used as test samples. This thesis contributes new knowledge for cleaning bone with ultrasound and generates a new design for an automated process for cleaning bones. ... Read more

Use of earth observation satellites have grown at a very high rate over the past few decades. On a closer observation of things around, most of them uses satellites, directly or indirectly. Satellites are being used in the day-to-day life without being aware of its application. Satellites are used for small things like weather report, communication to very large things like internet of things (IOT) and earth observation. Some CubeSats are also used for interplanetary missions. For the purpose of earth observation missions, the satellites are installed with an optical payload which is a camera. The cameras used for space are different from the regular camera and have special specifications in terms of the materials, components and the design which make them suitable for space missions. The optical payload which is to be launched has to be made sure that it can survive the launch and in orbit environment. This research focuses on the testing of these CubeSats and check if they are suitable for launch. The research starts with reviewing the testing procedure that is followed before the satellite is launched. A setup is provided for checking the performance of the camera mounted on the CubeSat and its suitability for launch. To investigate the performance of the camera, MTF and correlation techniques are used on different images to come to a conclusion. ... Read more

In high-precision complex mechatronic devices, specifications are mostly affected by the contribution of several disciplines. Thus, in order to facilitate the fulfilment of the specifications, it is crucial to have a well-defined requirement for each sub-system during the entire design process. Model based system engineering (MBSE) is a multidisciplinary approach with the aim of developing a balanced system solution in response to various stakeholder needs.
A multibody dynamics model is developed to break down specifications from system to sub-system level. An analysis of the impact of the motion of a 2 DOF mechanism is done. Special focus is given to the location and impact of the interaction between the Center of Gravity and Center of Stiffness to the reaction forces. The derived sub-system requirements can then be used as an input for mono-disciplinary early concept design.
... Read more

This study focuses on investigating an alternative validation method to validate the compressor side of turbochargers. Nowadays, the performance of turbochargers is tested using hot gas stands. These hot gas stands are expensive. The application of an externally coupled e-motor to the turbocharger eliminates the need for a hot gas burner - significantly reducing the cost. However, the validation range with electric motors is limited. Therefore, it is investigated if the circulation of the compressor outlet flow provides additional shaft power by the turbine. Thereby it would be possible to generate a bigger range of compressor performance maps in terms of power and rotational speed with a limited electric motor.
In the first part of the study the test setup is designed. The original e-turbo hardware was not available. Therefore a test setup is designed with a relatively high power output but low maximum speed electric motor. The principle of range extension will be proven in the lower speed range. The test setup will be used in two configurations. One where the compressor is only powered using the electric motor and the other where the electric motor and turbine will power the compressor. For both configuration the input of the electric motor is kept constant in order to validate if by adding the turbine a shift can be measured in the operating points.
In the second part, a performance expectation model is set up. The existing compressor map, turbine map and electric motor characteristics are used to determine which operating point can be validated. When the available electric motor and turbine power and torque are higher as the compressor values, an operating point is considered in reach. The model outcome is a compressor map that indicated which operation points can be reached with only the electric motor and with the combination of the electric motor and the turbine.
The result of the model shows that the outlet flow in both configurations always remains above 1 bar and 0 oC. This means that no freezing gas is expected to be generated. Furthermore, the model shows that for a selected operating point it is possible, depending on the flow control, to push the operating point to a higher rotational speed or mass flow value.
The aim of the research was to use an alternative method to validate the compressor of the turbocharger whereby validation range could be extended by means of energy recovery with the turbine. This study shows a test setup design and a performance prediction model that shows that it is possible to eliminate the use of a hot gas burner for compressor validation and use an electric motor together with the turbine to extend the validation range in a compressor map. However, within the time frame of this study, no physical test was performed due to the unavailability of different electric motors. Nevertheless, this study shows the potential for an alternative way of compressor wheel validation for turbochargers and contributes to the development of the electric assisted turbocharger.

... Read more

A wavelength modulated interferometer is presented, based on a telecom laser source. A solution for the target distance dependency of wavelength modulated interferometers is presented. With the introduction of a delay line, the modulation depth variation is reduced. A method and a sensor head for the reduction of the thermal dependency of this delay line are presented. The resulting interferometer has sub-nanometer non linearity errors and a thermal dependency of below 3 nmK¡1 with a working range of 1meter. ... Read more

Cryogenic electron tomography (cryo-ET) is currently the golden standard for imaging cellular tissue at nanometer resolution. The current workflow from cultured cells to final image is however very time-consuming, labor-intensive, expensive, and has a low yield. Moreover, many of the steps in this workflow require practice. Even after practice, experienced users often lose samples during the cumbersome cryo-ET workflow.
Clipping of the Autogrid is one of the manual steps in the current procedure that is known to have a low yield. During this procedure, the fragile 20 µm thick sample carriers (TEM-grids) can get damaged or contaminated causing the loss of valuable samples. After clipping, the Autogrid increases the stiffness of the sample carrier, enabling automatic handling of the samples. Clipping of the Autogrid can therefore be considered as one of the missing links for full automation of the cryo-ET workflow. This thesis was aimed at automating the clipping procedure, thereby improving the yield, reducing the time required for practice, and reducing the amount of manual handling steps of the current procedure.
A problem analysis on the current procedure for clipping the Autogrid was performed, based on which multiple solutions were designed and tested experimentally. Designed gripper fingers were used with a six-axis industrial robot arm to automatically handle sample carriers and Autogrids. Such procedures are done manually using tweezers in the current procedure. Damage induced on the sample carriers during automatic handling was quantified experimentally.
Automating the clipping procedure allows for adjusting the orientation of sample carriers during the procedure, which is currently (almost) impossible. For this purpose, a machine learning-based marker detection algorithm was used to automatically detect markers that are present at the bottom of an Autogrid. This detection algorithm was used with a stepper motor and a designed mechanism to automatically obtain a specified orientation of the Autogrid. Finally, recommendations were given on how the proposed designs could be used in a final automated solution. ... Read more

Vibration energy harvesters are especially interesting to use in an environment where there is one dominant vibration frequency present because then the harvesters can be designed to resonate at that specific frequency. To spread out the power yield over more frequencies a multi-modal harvester can be used which can resonate at multiple frequencies. A vibration with more than one sine wave can be manifested in a number of ways. The two frequencies can be present simultaneously, or they can alternate each other. How the energy harvesters react to these different vibration inputs is researched in this paper. Two fundamentally different multi-modal energy harvesters are used here. One which can be described by a coupled system of equations and one uncoupled. Two prototypes of an uncoupled and one coupled device are made and tested on an electromagnetic shaker. The vibration signals are sent to the shaker and the power output of the energy harvesters is measured using piezoelectric transducers mounted to the mechanisms. The results show that a phaseshift in the sine wave input signal generally results in a increase in power, where a decrease was assumed beforehand. When switching the input vibration from the first to the second eigenfrequency the power output does drop significantly, but the coupled mechanism has a substantially higher power output than the uncoupled device. And when the mechanisms are excited by a vibration with two eigenfrequencies at the same time no significant difference between the two can be observed, nor does the power output drop significantly. While the comparison between these two mechanisms is probably accurate, the quantitative conclusions must be taken with a grain of salt as it was noticed in a later stage of the research that the vibration signals were not consistent over the entire time period. At this point it is unclear if an overall better mechanism can be picked between the coupled and uncoupled one. However, it is shown that both have their distinct advantages where they outperform their counterpart, which can be used for designing a better energy harvester in future applications ... Read more

The ever increasing demand for better and cheaper electronic devices, sensors, optical components, etc. fuels innovation in nanometer precision positioning machines. However, the overall architecture of these machines has not changed much over the past years. A huge improvement in the architecture is currently impossible due to a crucial element of these machines -- namely, the gravity compensator. A gravity compensator is a passive element providing a supporting force that reduces the heat generation of the actuators in the gravity direction. Additionally, the gravity compensator is required to have a low stiffness to limit the disturbance forces due to vibrations present inside the machine. The state of the art gravity compensators are based on permanent magnets, as they are a non-contact solution providing the best performance and excellent vacuum compatibility. However, the current designs are limited to a single operating point. To enable the development of the next generation of nanometer precision positioning machines, a gravity compensator with an operating line is required. Therefore, the goal of this research is: “To design and experimentally validate a magnetic long-stroke gravity compensator for a nanometer precision positioning machine”. In this study the most suitable magnetic design was developed using various modelling techniques. Subsequently, the model and the design were validated by means of measurements taken with an experimental setup. From this study it was concluded that the design requirements can be met using high grade magnets. Thereby, with this Master Thesis, the first step has been taken towards the next generation of nanometer precision positioning machines. ... Read more

In 2018, there were more than 200 million reported cases of malaria worldwide, most of which were in Africa. Adequate diagnostics are required to properly treat the disease. According to the WHO, microscopic examination of a blood smear is the Gold Standard of malaria diagnosis. Currently, it is a labor-intensive process requiring trained personnel, expensive equipment and a lab-environment, which makes it unsuitable for use in field environments. Most of these problems can now be tackled with a smartphone microscope, which automatically identifies malaria parasites in a bloods smear. This solution is low-cost, suitable for use in field environments and excludes the need of a trained microscopist. However, it is still a labor-intensive process: 300 unique fields of view of a blood smear must be examined and doing this by hand takes a lot of time. To solve this problem, an (semi-)automated planar positioning stage is needed, which moves the smear in 2-dof, such that 300 unique images of the surface are acquired. The stage must be low-cost, robust and suitable for field environments. At the moment, there is still a lack of such a stage. Therefore, this research aims to fill that technology gap. The stage is designed to perform a motion pattern in 300 steps, whilst ensuring that the sample remains in focus and that there is no overlap between images. The design encompasses a coarse motion stage stacked atop a fine motion stage (combined, it is an $Rθ stage). The fine motion stage consists of a compliant rotary stage actuated by a stepper motor, generating cyclic motion of 40 steps (220 μm step size). After each cycle, the hand-actuated coarse motion stage displaces the sample one step (500 μm step size). The operation is completed after 8 cycles. A demonstrator is built to investigate whether the stage meets the requirements. The 3σ step precision of both stages ensure no overlap between images (11 μm and 30 μm) and the 3σ focus error during operation is small (δz ≤ 2 μm$). Consequently, we have successfully designed a low-cost and robust stage capable of meeting the requirements for this application. For future work, the stepper motor can be replaced 1-on-1 by a mechanical variant, eliminating the need of a power source and electronic components, whilst significantly reducing costs. ... Read more

Bone drilling is a crucial part of orthopaedic surgery. Internal fixation is a ommon orthopaedic procedure that requires drilling to improve healing of bone fractures. Tight spaces around hard to reach bone fractures impede the surgeon during the procedure. As a result there is an increased risk of complications such as thermonecrosis, overshoot into soft tissue, micro-crack formation and drill bit breakage. Therefore, a novel procedure is proposed, where drilling is done using a compact Self-Feeding Angled Drill Attachment (SFADA). The SFADA is a crucial part of the new procedure, because it can generate a controlled feed in a onfined space. Four concepts were developed that met these functionalities. Based on the design specifications a final concept was selected. The concept based on a differential thread and a lead/lag bevel gear was deemed the most feasible. Materials and dimensions were assigned to the mechanism based on an analysis of the critical components. A compact demonstrator of 80x40x36 mm was built. Measurements were performed and the results showed the SFADA’s ability to perform controlled drilling in a confined space. Furthermore, the SFADA can generate a speed of 1500 rpm and feed of 1.5 mm/s, with load forces and torques up to respectively 20 N and 0.2 Nm. The design of the SFADA is an important step in the improvement of bone drilling at hard to reach bone sites. ... Read more

As technology is advancing, the need for precision stages is increasing. These stages are being used with (electron) microscopes for scientific research and industrial applications. They can be operated manually or by actuators, where the motorized stages are quite expensive in general and the cost increase significantly if better performance is required. The increased cost is mainly due to the used sensors, such as linear encoders for stacked stages and laser interferometers for planar stages. It is a trade-off between the performance and cost. Alternative low-cost sensor systems have already been developed by the MSD group. A recent sensor system uses an 8-megapixel 2D image sensor with QR-like patterns to achieve micrometre precision and a relatively low sample rate of 16 Hz. This sensor system is limited by the sensor and the image-recognition algorithm. By using a cost-effective linear image sensor (2000 pixels) the same precision could be achieved while the sample rate can be significantly higher. This thesis presents a new methodology to measure the 3DOF(xyθ_z) of a planar stage with a single linear charge-coupled device (CCD) from a self-designed pattern. The feasibility of the methodology has been shown with a self-developed line scan simulation tool. A sensor system has been built and implemented in a demonstrator to gain knowledge about the different sensitivities in the sensor system and to demonstrate the possibilities of the sensor system.
... Read more

Flex-on-substrate assembly is an increasingly popular electronics assembly type that is based on thermocompression bonding: a combination of high temperature and pressure. Currently, up to two-thirds of the cycle time is spent on heating and cooling. To meet the growing demand for flex-on-substrate production in the future, the heating and cooling steps must be more time-efficient. In this thesis, a bonding module is designed that is heated and cooled by using a 150W halogen lamp as a heating source and a staggered-tube heat exchanger with forced airflow as a cooling system. The design requires understanding of the bonding process and models containing the governing physics. Therefore, finite element models were made for both heating and cooling which were validated by manufacturing a demonstrator and applying a typical thermocompression bonding temperature profile to the heating element. From the experiment it follows that the concept shows potential for further product development but does not yet perform as required. The reflector surface reflectance,which has an important impact on the energy efficiency, was too low in this demonstrator. Furthermore heat leaks away from the heating element which inhibits a fast temperature rise and the complex cooling system geometry leads to manufacturing errors, which cause leaks in the cooling channel. By improving the design on these points, this concept can decrease the current cycle time by more than 50% and keep up with the growing demand for flex-on-substrate assemblies. ... Read more

Vibration energy harvesting can become a durable source of energy for wireless
sensors or other low power applications like pacemakers. Huge savings in ecological footprint, production and maintenance costs can be achieved by replacing batteries for vibration energy harvesters. Most of the time, newly developed energy harvesters are tested in a lab environment on an electrodynamic shaker. The problem is that the standard lab experiments in the form of a sinusoidal or Gaussian noise signal excitation are not representative for the real world applications. In a classification of ambient vibrations it was observed that most vibrations found in the real world consist of a series of dominant frequencies, shocks and noise. It was also seen that among real world vibrations, there is a lot of variation in the power distribution among the classes. In the aim to bring the vibration energy harvester performance tests closer to the real world applications, an experimental benchmarking of energy harvester performance has been conducted. An energy harvester is designed and applied in the real world on the engine of two different cars. Successively, three different lab experiments are performed on an electrodynamic shaker, each experiment with its own type of vibration control. It is found that only taking the FFT data of a real world vibration is not sufficient. Using a sinusoidal excitation matching a single amplitude and frequency, or even a noise excitation matching the entire power spectrum, results in an under or overestimation of 50% compared to the real world performance. Therefore, to accurately predict the performance of an energy harvester in the real world, simulation or experimental testing need to be performed on the actual or a replication of the intended real world vibration. ... Read more

Malaria remains a major burden on global health, with roughly 200 million reported cases worldwide and more than 400,000 deaths per year. According to the World Health Organization, ninety-three percent of all deaths due to the disease occurred in developing countries in sub-Saharan Africa. This large percentage is directly correlated to the lack of diagnostic tools in those developing countries. Early and accurate diagnosis of malaria is a critical aspect of efforts to control the disease. Microscopic examination of a blood smear remains the clinical gold standard for malaria diagnosis. However, this examination is subjective and requires a highly experienced and skilled microscopist. Next to that, it is a labor-intensive procedure that is very time-consuming. Automated hematology analyzers that are currently available are of high cost and therefore only suitable for laboratories and not for a local doctor’s practice. The objective of this research was to provide the design of a compact and affordable compliant XY positioning stage that can be integrated into a microscope to be used for automated malaria diagnosis in developing countries without the involvement of a laboratory. The challenge imposed with this objective is that compliant stages can only reach small strokes due to the inherent imperfection of flexures. Achieving long-stroke results in high stresses and cross-axis coupling between the two motion axes which is undesired. This challenge is solved by implementing a constraint-based method that results in a design with parallel kinematics and modular structure that exhibits high geometric decoupling. A demonstrator of the precision stage is 3D-printed out of PLA and used for performance evaluation measurements. The demonstrator managed to achieve the set requirements for blood smear analysis. Therefore, it can be concluded that the stage was designed successfully and it can be implemented for automated malaria diagnosis to help Africa control the disease. ... Read more

Nowadays, low-duty CNC machines use the conventional belt-driven system, which works well for relatively small machines. However this design brings several complications the engineer has to account for: creep; backlash; complex assembly and more importantly the limited stiffness of the belt. This limited stiffness results in belt stretch and induced vibrations, which ultimately reduces the final accuracy of the manufactured product. In order to compensate, the accelerations are limited, which is a very important factor for fast manufacturing. High speed and fast positioning is hard to achieve with the current belt-driven design used in for example 3D printers and CO2 laser cutting machines. For that reason a different motor type is considered: direct-drive technology. These motors cost minimally 700 euros per meter stroke when outsourced.
In this thesis presentation the design and optimization of a low-cost direct-drive motor intended for low-duty CNC machines is presented. The motor is able to achieve up to 10 [m/s^2] acceleration and a speed of 1 [m/s], with an accuracy of a human hair. This should help boost the effectiveness of low-duty CNC machinery. Smart design choices, and low-cost components further reduce the total cost down to under 100 euros per meter stroke. ... Read more

Stick-slip friction is the resulting effect of the transition between the dynamic and static friction coefficient. This effect determines the minimal sustained speed and minimal incremental motion of a movement system, limiting the performance in precise positioning systems. Available bearing types without stick-slip suffer from complexity, high cost, energy storage (for example in flexures) or need for active components (for example in magnetic bearings). The ferrofluid bearing has none of these issues. This makes it a potential alternative for current bearings in precise positioning systems. Ferrofluid is a colloidal suspension of magnetic particles in a carrier liquid. This gives the unique property of a fluid that is drawn towards the highest magnetic field intensity. The ferrofluid can be used in two ways to construct a bearing; the pocket bearing and pressure bearing arrangements. This research focuses on the latter, as the pocket bearing has shown bad repeatability. The pressure bearing consists of a ferrofluid in a magnetic field in between bearing surfaces. As a load is applied, the space between bearing surfaces decreases. This results in the ferrofluid being displaced from the least energetic configuration in the magnetic field which induces a normal force on the bearing surfaces. The objective of this study is to improve the performance of the ferrofluid pressure bearing by removing or improving the limitations in stroke length and repeatability. This is done by the creation of a longstroke linear ferrofluid demonstrator stage. The challenges in the creation of this stage are primarily focused on limiting the effects of trail formation, addressing the evaporation of the ferrofluid, and achieving a sufficient load capacity and stiffness to be a feasible alternative to other bearing types. ... Read more

This report presents a new filter wheel design for use in space-based optical systems. The design integrates a hybrid linear stepper motor into the wheel's rim to generate rotation, leading to a Rotating Hybrid Linear Stepper Motor (RHLSM). Unpowered this motor generates a holding force that can keep the wheel in position during system vibrations. A model was made and simulations were done to investigate motor behaviour and the effect of design parameters. A breadboard was developed to validate motor performance and investigate manufacturability. Design considerations are summarized. The report demonstrates that the RHLSM driven filter wheel is a mechanically simple, robust and compact design. The design shows great potential for a long life time and component cost reduction, and might find use in applications beside filter wheels as well. ... Read more

The Nobel Prize in Chemistry in 2017 went to the development of cryo-electron microscopy, which contributed to the discovery of new cells and viruses, the diagnosis of unknown diseases, the mapping of human genomes and the manufacturing of semiconductors. Cryo Correlative light and electron microscopy (Cryo-CLEM), is the combination of using fluorescence microscopy and cryo-electron microscopy to image cryo-immobilized bio-samples. These samples (at a temperature lower than −165ᵒC), require critical conditions in preparation and preservation to prevent contamination and heating which have a negative influence on the imaging results. In the current sample transfer workflow, almost 90% of the samples transferred end up being wasted due to the unideal protection and transfer gap. Therefore, an integrated high-vacuum sample transfer system which fits the interfaces of CLEM devices and actively protects the samples from heating and contamination in transfer has been designed to conquer the problems, ensure better imaging results, and increase the process yield. COMSOL simulations on its thermal and mechanical behaviors have been carried out to theoretically verify and iterate the design. The new transfer system provides a cheaper, faster, easier, more contamination-free, more temperature-stable, more user-friendly workflow that can increase the yield of sample transfer from 10% to 90%. ... Read more