The company invented a product that can monitor vulnerable people. It is important that they know exactly where their products are located. If a situation occurred where a vulnerable person needs immediate help, first responders can use the knowledge of the location to get to the patient as fast as possible. This thesis investigates if a modular localization solution can be designed for this product. The product will always be located in an indoor environment, which is a difficult place to establish the location. A modular solution is interpreted as a system that has parts that are replaceable. Some parts can be switched out for different parts with the same functionality, with the system still working properly. In order to design this system according to the requirements, the design process was divided in hardware and software. Both were designed in a modular way, yet eventually implemented in one specific way. This was done to get a tangible prototype that could be evaluated and tested. Improvements to the system were also designed, however could not be implemented in time. Nonetheless, the resulting system works well under conditions of intended use. There were some conditions in which the system performed less than required, however this should be fixed once the improvements are implemented. The results indicate that the localization system that is needed for the company's product is possible to be implemented. The next step is to research whether parts of the modular system can be replaced by an improvement. Then the system can be tested in more distinct working conditions, which could not be done during this project. If the system passes these tests, it is ready to be integrated with the other subsystems of the product, such that the company can bring their product to the market.

Today’s cars are undergoing the greatest transformation the industry has seen. Power MOSFETs play a crucial role in making electronics more energy efficient by driving down switching losses and Rdson using a combination of next-generation trench technology and ultra-thin dies. Power MOSFET dies are becoming larger ( > 5 X 5 mm ) and thinner ( < 50 μm ) to meet the high performance lifetime requirements of the automotive industry. The high aspect ratio and the new chip designs with trench technology offer challenges for assembly, packaging and testing. The majority of the research performed in the past, aimed to reduce the risk of die crack by improving equipment and process strategies in back-end semiconductor processing. This thesis study aims at improving die strength from a front-end approach (device fabrication process) by making dies stronger to stress from die frontside. New chip designs are presented with new metal layer layouts for improved stress distribution. Materials like polyimide are investigated as new die top material for mechanical strengthening of die frontside. Key factors which influence die strength like trench-metal interaction, wafer stress and warpage are also analyzed in this thesis report. In this study, ultra-thin power MOSFET dies are realised on 100 mm diameter silicon wafers with dimensions of 6 X 3 X 0.050 mm. These dies are mechanical equivalent in design, robustness to commercial trench power MOSFETs. The processed wafers are grinded from the backside to realise 50 μm thin wafers which are then sawned to obtain singulated dies. The strength of the dies are characterized by three-point bending tests and analyzed using probability plots for weibull distribution.

This thesis describes the design and implementation of a subsystem within a larger medical monitoring system. This subsystem will make bidirectional audio communication possible between a patient and their caregivers or family members. The patient in question can be premature babies that have to stay inside of incubators and elderly people that need to be monitored for their health. The designed subsystem is tasked with creating an audio stream that goes bidirectionally between a speaker with a handsfree functionality and the front end via a server. On the server the audio from the patient should be stored on a hard drive. Whether the audio communication should be stopped or started and whether the audio should be stored will be controlled by the front-end user. Initially the goal was to implement the solution on a Pine singleboard computer (SBC), but due to unforeseen delays of the delivery of the necessary Pine SBC, it was decided that a proof of concept would be developed. The future work in this thesis will discuss the portability of the solution to the Pine SBC.

Fluid accumulation in the human body is, in many cases, a symptom of some underlying pathological condition. Most common examples include edema, ascites, pleural effusion, and internal bleeding. Currently available non-invasive methods to assess fluid accumulation in the body are mainly imaging-based (i.e. ultrasound, computed tomography). This means that monitoring is limited to spot-checks and is only performed when the presence of a particular condition is already suspected from prior clinical evaluation of the patient. There is high clinical interest in the development of a system allowing such monitoring to be performed automatically, continuously over a prolonged period of time, and independently of prior clinical evaluation. For instance, in the case of internal bleeding, hemorrhage indicators such as variation in heart rate and blood pressure are only observable after significant blood loss (up to more than 1 liter) has already taken place, therefore an early warning system can save lives, decrease hospital stay length and significantly reduce complication-related costs. In this thesis, a pioneer solution is proposed for development of such a monitoring system. The hypothesized solution is based on the observation of specific energy-describing features of the Ballistocardiogram (BCG) signal, a measure of the periodic displacements generated on the body as a result of ballistic forces produced by the heart during each cardiac cycle. Because of additional damping generated by the presence of internally accumulated fluid, the energy of this signal is expected to decrease compared to its baseline value. The BCG can be recorded unobtrusively with different sensing modalities on the surface of the body. In order to validate the research hypothesis and assess the feasibility of this novel technique, a custom experimental set-up exploiting several different BCG sensing options has been used to carry out a study on 15 human volunteers. Localized fluid accumulation along the GI tract was induced in a controlled, safe and simple fashion, by means of water intake by the participants, and the BCG signal was recorded before and after intake. Signal feature exploration and performance analysis has been used to develop an optimized feature able to accurately capture the decrease in signal energy due to fluid accumulation, as well as to identify the most suitable sensor type and monitoring body location for the present application. The developed energy-describing feature shows a significant decrease in energy value from baseline to after-intake condition with a p-value<0.001. Moreover, the selected feature was able to correctly identify presence of fluid accumulation with high sensitivity (90% in bed-based, and 100% in standing-position monitoring). Given the promising results of the present study, further research towards improvement and development of the proposed technique is highly encouraged.

Classical computer have difficulties simulating specific complex problems, therefore other computation options are being explored. One of these options is the quantum computer, which is expected to excel in various industries. The challenge for the quantum computer is scaling it up to a high number of qubits. The diamond-based quantum computer is a suitable candidate for quantum computer, because it can be made scalable, with long coherence times, relatively high temperatures and low cross talk. Making such a scalable modular quantum computer using diamond qubits requires heterogeneous integration of optical components. Multiple integrations techniques for optical components exist, however in this thesis we are particularly interested in integrating a superconducting nanowire single photon detector (SNSPD) with pick & place onto the quantum chip to read out the photons emitted by diamond color-centers. The main goal of this thesis is to find out which integration scheme leads to the highest on-chip detection efficiency of a pick & place on waveguide integrated SNSPD. In this work we designed a silicon nitride structure with low loss tapered support structures. Next different releasing methods are introduced to release the fabricated silicon nitride structure independent of the material stack and with a high yield. Lastly, we show how waveguide structures can be pick & placed on receptor chips that underwent surface treatment.

This document reports details the development of a solid stool detection system. On behalf of Momo Medical - a TU Delft-based startup company - a device for detecting defecates by elderly people has been designed. The goal of the detection system is to detect solid stools by elderly patients wearing a diaper and to notify the nurses in a nursing home accordingly. The project has been organized and conducted in two groups: Hardware & Software. Our group has been in charge of the hardware. The other group has been responsible for the software. The main focus in this report will be the hardware design of the system. This report contains: the analysis of the problem, the development of a solution, the design and the evaluation of the device in test. The developed device detects methane by means of multiple gas sensors, since methane is the main gas component released while defecating. Several iterations making a suited printed circuit board and case have been carried out, while taking aspects like safety, reliability and noise performance into account. The report concludes with a summary of main results and an outline of future work.

This report is part of a bigger project to design a fall detection system for elderly and describes the hardware of the system. The importance of this research is that elderly can live longer in their home by alerting the correct instances in case of an accident. The hardware consists of a 1x2 meter sensor grid below the surface of the floor. The sensor grid uses the piezoresistivity of linqstat to measure the pressure and the location of the pressured point on the floor. An ESP8266 microprocessor combined with 74HC595 shift registers and a 74HC4067 demultiplexer is used to gather the data and send it to a server. The design is modular allowing easy installation in differently sized or shaped rooms. Each individual sensor grid has an update frequency of 14Hz and uses wifi to connect to a common server. Each module has an average power consumption of 0,74W and a peak power of 1,6W.

This report describes the design and implementation of an interface subsystem for a fall detection system using a pressure based floor sensor. The goal of the fall detection system is to detect and alarm when an elderly person has fallen. The subsystem covers communication between hardware and software, using the WiFi protocol MQTT. The communication is fast enough so that it does not limit other subsystem performance and allows for high expandability to accommodate the hardware’s modular design. The interface module receives a probability of fall occurrence from the separate processing module, from which an average is taken over a 30 second time window to avoid false positives. Alarming is done through the use of text-to-speech voice API to make automated phone calls that retrieve user input to confirm or deny that help is on the way. A habit tracker proof of concept is provided that could improve the accuracy of fall detection by checking if the client is showing anomalies during a given day. A user interface is implemented using the Kivy environment. This environment has its own language which allows for separation of functionality and layout, which keeps the interface elements separate and leads to ease of use. Overall, this results in a strong alternative for fall detection that could be used to improve the time an elderly person can live at home safely without the need to move to a nursing home.

This report details the design of an instrumentation system to be used on a skeleton sled. The system will measure several quantities on a skeleton track for the athlete to learn from. This data is stored during the run using several sensors on the sled and processed and visualised immediately afterwards on a mobile device. The project is tailor-made for skeleton athlete Akwasi Frimpong: he requested a way to get some insight in his steering using his knees and shoulders and its results on his achievements. This thesis focuses on the data processing, communication and visualisation of the data and the software integration of all sensors. The communication is done using Wi-Fi and the visualisation is realised with a web page. The whole system is implemented with an ESP32 microprocessor which functions as a Wi-Fi access point and web server for the user interface.

This report presents a proof-of-concept for a sensor measuring the ionic concentrations in sweat using cyclic voltammetry. Development is focused on feasibility of the sensor. Theoretical evaluations of voltammetry as a working principle and its physical and electrochemical foundations are guiding principles of the design. The sensor is then implemented using commercial components. Experiments show that the sensor has good sensitivity and linearity for single ions in the physiological range. For the measurement of multiple ions the voltammogram is characterized in-depth. A matrix of different ionic fluids with multiple ions is prepared and two independent parameters for the concentration of two ions (sodium and potassium) are found, proving the concept of the sensor for more complex solutions. The usability of the sensor is verified using a sweat sample. Different influencing factors are researched and their impact characterized. Varying electrode materials are evaluated considering durability and sensitivity. Conclusions are drawn and an outlook for future research on this type of sensor is given. The concept of the sensor is proven to work within certain limitations.

In the last 4 decades, surface electromyography (sEMG) signal processing has been applied to detect local muscle fatigue, this non-invasive approach is suitable for detecting EMG signals generated by athletes in motion. Also, EMG could directly reveal the muscle’s performance like endurance and recruitment of motor units, which is hard to be obtained by other methods. With the sEMG system, we can research whether EMG signals can be used to measure muscle fatigue and how this relates to injury risk. This thesis aims to build a sensor node for sEMG to detect local muscle fatigue. An sEMG system is built for this purpose, and a physiological experiment is designed to collect sEMG signals from human muscle (Vastus Medialis) using the sEMG system. Both isometric and isotonic exercises are studied. The data analyzing method is calculating mean power spectrum frequency (MNF), median power spectrum frequency (MDF), and muscle fiber propagation velocity (MFPV) of the collected sEMG signals, because local muscle fatigue is related to MNF/MDF decrease and MFPV decrease. 5 groups of isometric exercise, wall-sit and 2 groups of isotonic exercise, cycling, are recorded. All the athletes are healthy males, around 25. The data analyzing result shows that MNF/MDF decrease is related to muscle fatigue, and MFPV changes similarly with MNF/MDF.

Background: The Fontan procedure is the last of three stages of congenital heart surgery to treat children born with a single ventricle heart defect. In these patients, a balanced hepatic blood flow distribution (HFD) towards both lungs is important, since a lack of “hepatic factor” has been associated with the formation of pulmonary arteriovenous malformations (PAVMs). With imaging modalities and computational fluid dynamics (CFD), the hepatic blood flow distribution can be studied. Recent CFD studies indirectly quantify HFD to both lungs by tracking ‘hepatic flow’ particles that are uniformly seeded in the Fontan tunnel and analyzing the distribution of these particles towards both lungs (conventional approach). However, this approach is based on the unvalidated assumption that there is a uniform distribution of hepatic blood flow in the Fontan tunnel. Aside from CFD modeling, previous clinical imaging studies showed that respiration has a tremendous impact on the hepatic blood flow in Fontan patients; however, these studies only used Doppler Ultrasound because the resolution of real-time phase-contrast magnetic imaging resonance (PC-MRI) is not yet good enough for direct hepatic flow quantification. Objectives: this study aimed to investigate the distribution of hepatic blood flow in the Fontan tunnel using CFD simulations. Another objective was to quantify the HFD towards both lungs using particle tracking directly from the inlets of the hepatic veins (novel approach) and compare these HFD results to the conventional approach. Furthermore, we performed an in-depth flow analysis and developed a new method to indirectly quantify the hepatic flow in the hepatic veins and the respiratory effects on it using real-time PC-MRI. Methods: Unsteady CFD modeling was used to assess the mixing of hepatic blood flow within the Fontan tunnel and the different HFD quantification methods. Therefore, we created three-dimensional reconstructions of the patient-derived Fontan anatomies based on MRI imaging that included the geometry of the hepatic veins in the computational fluid domain. We created two types of CFD models: 1. CFD models that only included the cardiac effects on blood flow, and 2. CFD models that considered both the cardiac and respiratory effects on blood flow. For the in-depth flow analysis using real-time PC-MRI, we first measured the blood flow in the Fontan tunnel, just above the entrance of the hepatic veins. Second, we derived the IVC blood flow below the hepatic veins. By subtracting these flows, we indirectly quantified the hepatic blood flow. Results and conclusion: The main findings were that hepatic blood flow was non-uniformly distributed within the Fontan tunnel and substantial differences in HFD between the conventional approach and novel approach were found in both types of CFD models that either ignored or considered respiration. Additionally, we showed that it was feasible to indirectly measure hepatic blood flow in Fontan patients while using real-time PC-MRI. These derived flow parameters extracted from real-time PC-MRI acquisitions confirmed what previously has been described that the hepatic blood flow in Fontan patients was heavily influenced by respiration.

Ultrasound (US) neurostimulation, the non-pharmacological, reversible excitation or inhibition of the nervous system using ultrasonic waves, is emerging as a high interest topic in neurostimulation research. In the current project, an attempt was made to demonstrate US neuromodulation in a Lumbricus Terrestris model of evoked compound action potentials (eCAP). Hardware and software for the electrophysiological observation of local field potentials were designed and assembled. The resulting system was used to perform mechanical, electrical and both direct and indirect ultrasonic neurostimulation experiments. It was shown electrical stimulation could be performed reliably in-vivo and ex-vivo. Mechanical stimulation only functioned in-vivo. Additionally, power transfer experiments showed that deeply embedded CMUT devices can be used to harvest acoustic power and use this signal to stimulate an explanted Lumbricus Terrestris medial nerve cord. Direct ultrasound neurostimulation was however not observed, likely due to a combination of misalignment and incorrect acoustic pressure profiles. As an additional project, a microfabrication step was designed and performed for the etching of high aspect-ratio silicon bulk structures for the backside venting of low frequency CMUT devices. A two-step process deep reactive ion etch (DRIE) was attempted where smaller features were first introduced into the silicon (phase A) and then advanced using a larger etch frame (phase B). It was shown that phase A etching could be performed adequately, resulting in high quality deep silicon etch profiles with minimal tapering and an excellent etch rate. However, phase B etching resulted in the consumption of side-walls and removal of previously etched features. It is likely some slight adjustments to the passivation stage of the DRIE process would result in successful completion of this fabrication step. Acknowledgements

Decreasing injuries in football is a topic of interest for the KNVB and KNHB. To reach this goal, the use of smart sensor pants is researched. The data will be used to develop models for finding injury risk factors that are related to movements. Currently, the system is capable of reading out the IMUs and storing the data on an SD-card, for post-analysis of the data. As next step, the communication link should be implemented, for real time feedback to the football players. The design of an efficient communication system in terms of power, size, and reliability, is quite a big task. By looking at similar research to body-worn devices, it is noted, that most devices deal with a 10 times lower data rate than the current device. On top of that, it is noted that the absorption of the body is causing problems on the link reliability. Based on these observations, it is decided to focus the research of this Thesis on the reduction of the data load, and the optimization of the transmission part of the smart sensor pants. The Thesis is split into two parts, the first part will show the use of lossless data compression. The second part will start with showing the benefit of using a patch antenna over a dipole antenna and continues by showing the benefit of using a dual antenna configuration over a single antenna configuration. To be more specific, the first part of this Thesis starts by comparing different lossless data compression algorithms, from which the FELACS algorithm is chosen as most suited. This algorithm is then implemented on the current hardware and tested on data from the smart sensor pants in a realistic football scenario. These results show an average compression ratio of 43 %-45 % in the most intensive 5-minutes of a football game, with a minimum of 38 % in an interval of 10 s. To improve the compression algorithm, an adjustment to the FELACS algorithm is proposed. This adjustment is theoretically tested and shown to outperform the FELACS algorithm with a higher compression ratio. In the second part, the use of a dual antenna configuration is discussed, whereby the use of a patch antenna is compared to a dipole antenna. It will be shown, that a dual antenna configuration can significantly improve the signal strength around the player, resulting in an almost isotropic radiation pattern, using pattern diversity. On top of that, this form of pattern diversity is observed to increase the reliability of the link, using switched combining. Moreover, it will be shown that a patch antenna will be more suited for this application, due to the higher gain in the front, and the robustness against interference when placed close to a conducting material. In summary, the two main contributions of this Thesis, are the reductions in data load, and the testing and verification of the dual patch antenna configuration. These contributions provide the basis for the communication part of the smart sensor pants.

Distributing power and data around a garment is a common problem in sensor enabled e-textiles, as connecting separate electronic subsystems together using connectors and wires has proven to be unreliable and cumbersome. In this work a solution is presented that will eliminate the connectors by using two pairs of short-range wireless inductive links. The proposed system is able carry power from one node to the next, while at the same time facilitating data transfer between the nodes. In this work the double inductive link is analysed, and a novel compensation topology is presented. A modified class-E amplifier is proposed to generate a carrier signal, improving the system settling time. Using a placeholder data protocol the system is able to transmit 62mW of regulated power to an external load at a total efficiency of 7.3%, while simultaneously transmitting data at a rate of 8.5kbit/s. Without data transmission it is able to deliver 185mW of DC power at 6.09V unregulated, at an efficiency of 23%. The system is also shown to be capable of handling a maximum bitstream of 240kbit/s.

Energy harvesting has become a popular topic for battery substitution in recent years. In particular, mechanical vibrational energy, one of the most common energy sources, has been intensely studied. Piezoelectric materials play a crucial role in vibrational energy harvesting as they can directly convert the mechanical energy to the desired electric energy. In particular these are attractive when they are made into a cantilever form allowing the harvester to harness larger energy. This project aimed at optimizing the performance of single-layered piezoelectric cantilevers, also known as the unimorphs, from the point of view of output power and operation lifetime with the use of a stroke limit stopper. \ In this study, a cantilever beam consisting of PZT (PZT5A4) bonded to an elastic substrate (Pernifer 45) with a tip mass attached to the free end is used as the harvester. To reduce the cracks generated in the piezoelectric material and subsequently increase the lifetime, a limit stopper is introduced to constrain the deflection of the unimorph.The influence of the stroke on the lifetime and power output is shown by a series of vibration tests under different operation conditions with varied unimorph lengths, configurations, attached tip masses and stroke distances. The result confirms the possibility of the limit stopper to improve output energy of longer unimorphs in certain distance ranges. It also points out that current designs do not allow performance optimization in both output and lifetime simultaneously. One ought to choose one of the two, as the methods which increased the instant power output also resulted in a sharp reduction in lifetime as well as total power capacity.

Drones are unmanned flying vehicles, which can be used for a broad spectrum of different applications. One of these applications is the generation of albedo maps. However, it could take some time to map an area. Therefore problems can occur the with respect to its flight range, which typically lies between 20 to 45 km for mini UAVs. The goal of this project is to design a PV powered drone that can create an albedo map of an area that is equal or bigger than the area of the Technical University of Delft. This is done by choosing and modelling an UAV system, where after choosing and modelling a PV generator system. Based on these models, power dynamics and flight ranges are calculated. The usability is tested for different weather conditions of Delft. The UAV system with PV generator without protection layers has a flying range between 129 and 250 km, depending in the irradiance. For the same system with protective layers, the flight range varies from 117 to 208 km. the total flight range that is needed to map the area of the TU Delft is 48.75 km. Therefore, there can be concluded that in both cases our goal has been achieved. When these results are compared to the weather conditions of the TU Delft, it can be concluded that on average a UAV system with PV generator will increase the flight range. However, when comparing this system to a system with additional batteries, the latter will achieve better results. In order to make sure that the PV generator system will guarantee a longer flight range, limitations regarding times, periods and places are made. Keep in mind that since these results are solely based on models of systems, it's best to create and test the physical system to validate the found results. This thesis is written in context of the Bachelor Graduation Project. We would like to express our gratitude to our daily supervisor Patrizio Manganiello and our supervisors Andres Calcabrini and Mirco Muttillo for their guidance during the project.  Finally we would like to thank our colleagues: Laura Muntenaar and Sjoerd de Groot of the control algorithm project and Jetse Spijkstra and Martin Geertjes of the power electronics project for an enjoyable and productive collaboration. J. Koning & R. van der Hoorn Delft, June 2020

This report details the software part of the development process of the eNose technology. The technology is posed by Momo Medical. Momo Medical is a start-up company located in Delft, it provides and develops non-intrusive monitoring systems in the nursing sector. The project is the next step in an already existing product: BedSense. BedSense enables nurses to check for among others decubritus, whether the patient is out of bed, and even if the patient has passed away. The finished project will be able to detect solid stool and hence, when integrated into the system of BedSense, will greatly assist the nurses. The eNose technology is able to detect solid bowel movement using its gas sensing abilities. It consists of gas sensors that detect the relevant gasses that are related to feces. These sensor values are then fed into an algorithm that is able to interpret them and detect defecation. Besides it includes a communication system that handles the internal and external communication. Finally, the technology supports Over The Air (OTA) updates which allows to update the firmware of the devices remotely. The final prototype functions accurately in certain restrooms and can be regarded as a proof of concept.However more work and data is needed in order to make the eNose work in various environments, with possible integration of machine learning analysis, as it has showed great potential. The project is executed in two groups, hardware and software. This report contains only the software part of the process. It includes the development of the detection algorithm. And the developmentof a communication and OTA programming system.

Pressure ulcers, also known as bedsores, are wounds that form when a person sits or lays in the same posture for an extended period of time. Continued pressure being applied to the same spot causes the skin to decay, possibly continuing into underlaying tissue if the wounds are not treated. A common and proven practice to prevent pressure ulcers from forming is to regularly change the posture of the patient, so that there is not too much pressure on any one part of the skin. Momo Medical is creating a sensor system to assist in preventing pressure ulcers. They already have a prototype using force-sensing resistor (FSR) and piezoelectric sensors to measure changes in posture of the patient. The prototype is able to detect if a patient has moved enough, whether on their own or by the nurses, to prevent pressure ulcers. The prototype works, but they need their system to be more reliable. The research in this thesis focuses on improving the piezoelectric sensors. Momo Medical uses the piezoelectric sensors to measure human bio-signals, mainly respiration and heart rate, through the mattress. Two different printed circuit boards (PCBs) were designed as test set-ups to be able to easily modify the amplifier to measure the piezoelectric sensors separately. Using these test set-ups two common piezoelectric sensors were compared, namely lead zirconate titanate (PZT) and polyvinylidene difluoride (PVDF) sensors. From this comparison it was concluded that the PVDF sensors consistently have a better signal-to-noise ratio (SNR), but that both the PZT and PVDF sensors were able to measure human bio-signals effectively. The PVDF sensors did showed even more promising results when using them in a different mechanical configuration. In the test set-up the amplifier was also changed to improve the read-out of the sensors. Multiple iterations on the amplifier design were tested. In the final design a non-inverting amplifier was chosen to decouple the amplification from the input impedance of the amplifier and a input impedance of 100MΩ was chosen. Because of the high input impedance in the final design the signal was dampened less and less amplification was needed, thus reducing noise.

In the past decades, the workload and the pressure on medical personnel has been growing to an unprecedented peak. This is partly due to the ageing population and the increasing capabilities to be independent at an older age, increasing the age people enter nursing homes. This paper focuses on a novel way to detect incidents that could occur in the daily life of the elderly. Unlike most systems already proposed by others, there will be no use of wearable positioning sensors and the system is implemented on an Single Board Computer (SBC). This thesis report is one of a set of two reports discussing the final implementation of the system.