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.

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.

The goal of this project is to identify the most promising measurement method and strategy for measuring the thickness of grease and to design a sensor module with electronic read-out and communication module. This project has been split into two parts: a sensor implementation and a communication system. This report describes the design and implementation of the communication module and power supply. The communication module has been designed to work conform a master-slave principle using MODBUS over an RS-485 databus. The used hardware for the communication module is rated to work within a desired 1 to 100m range. Furthermore the master node is connected to the internet to present the data on a small webserver. The power supply design depends on the implementation of the sensor, and contains the use of linear voltage regulators and inverters. The results show that the communication module works properly, whereas the power supply requires some further work.

Clean drinking water is still not widely available around the globe and therefore remains an unsolved issue. In fact, 1 in 9 people lack daily access to safe water and sanitation. Groundwater is a water supply source that needs minor treatment and thereby presents itself as a good solution to this global issue. Especially in development countries for example in East Africa this would be a viable solution. One interesting exploration method to detect groundwater in an area is airborne Frequency Domain Electromagnetic (FDEM) survey. However, most airborne EM survey instruments are expensive and bulky. Even though that this exploration technique has been around since the 50s, a commercial inexpensive airborne FDEM instrument has still not penetrated the market. This thesis describes the investigation of a novel portable FDEM survey instrument that will be employed by an Unmanned Aerial Vehicle (UAV). The system architecture for the measurement instrument is presented and the functionality, design considerations and requirements of each system block is given. To check the feasibility of the proposed architecture, a handheld Proof-of-Concept is implemented, which can carry out measurements between 100 - 12.000 Hz. The experimental measurement results of the Proof-of-Concept at operating frequencies of 925, 2175, 5025 Hz are presented and compared against measurements of GEM-2A instrument, which is employed as a reference.

This thesis tries to find a solution for the problem of managing and monitoring the banana shelf in a supermarket using IoT. The research focuses on using a wireless sensor that detects some features of the banana shelf while being non-intrusive. The three main features that are examined of the shelf are the quality and quantity of the bananas and the quality of the shelf. First a research was conducted to find the best sensor to use for these measurements. The chosen sensor is a color image sensor, the platform for the IoT device is a Raspberry Pi. Using the python programming language in combination with the openCV library image processing was used to detect the features. The image is first smoothed using a Gaussian filter, afterwards the foreground is segmented. The different segmentation methods are researched and adaptive thresholding is used. To determine the quantity of the bananas and quality of the shelf the stickers on the bananas are detected. This detection is implemented using different filtering methods ranging from spectral filtering to color thresholding. With the segmented foreground the quality of the bananas is assessed using a color histogram. This information is then sent to a communication module that is connected to a IoT dashboard for user interpretation. With the proposed design the status of the shelf including the percentage of the shelf filled, the quality of the bananas on the shelf and the neatness of the shelf are available for a supermarket manager to better organize his supermarket. This sensor makes it possible to better organize the banana shelf and act preemptive instead of reactive.

During 9 weeks of investigation multiple solutions for implementing a communication module in a supermarket have been explored. These results led to three options which have been further researched. Bluetooth Low Energy (BLE), 433 MHz and ZigBee have been selected as the best communication protocols for sensor to gateway communication. Chips for these protocols have been bought and for BLE and 433 MHz libraries have been developed. For the gateway and the communication to the server a Raspberry PI and Mobile Internet have been selected and these have been integrated. During the measurements we came to the conclusion that for the RFM69HCW (433 MHz) and the BLE Nano (BLE) the sleep mode did not work as specified. Resulting in high power consumption and thus worse battery life (sleep mode consumption for RFM69HCW 3.37 mA, BLE Nano 4.38 mA and for XBee 43.2 휇A). The final conclusion of this thesis is that, with the current research, XBee (ZigBee) is the best communication protocol for communicating within a supermarket. But in further research BLE Nano and RFM69HCW can perform better if the sleep mode is improved to work according to what is specified.

This thesis proposes a low-cost and small size customized data acquisition sensor badge, called Easy ID, which is specially designed for the Vision Lab Group in TU Delft for their on body data capture during social events. Easy ID is designed based on an open source platform, which provides enough space for future upgrade and extension. The innovate infrared communication algorithm and the open source software created to drive the circuits in this thesis can be shared with other similar implementations. Instead of using C/C++ language, this work uses python to enhance the code readability for our clients and realize a high-level programming method to drive hardware. To overcome the delays while modulating the transistors, a 555 oscillator is adapted, for a 38kHz carrier frequency. The performance of Easy ID’s identification is evaluated under both static and dynamic scenarios. With the infrared communication modules, the Easy ID can detect any facing another Easy ID with a range of 120 degree opening angle and 3.5 meters distance. The sampling frequency of motion capture is typically 20Hz with 9 DoFs inertial sensors. A highly accurate global time stamp can be stored combined with the data from sensors as data logs.

According to recent survey [1], about 6 billion people live in Low-and-Middle Income Countries (LMICs) who do not have proper access to safe surgical care. There are several reasons behind this, such as lack of funding to the healthcare department, below par maintenance of the available devices, poor infrastructure and most importantly high cost of the surgical equipment necessary in an operating room. A bipolar vessel sealing system is one of the many devices which is required for laparoscopic surgery and new innovations in the vessel sealing technologies have transformed the ways of electrosurgery as these devices perform surgery in a safe, reliable and efficient way with minimum operating time and reduced blood loss. Unfortunately, these units have been extensively designed and developed for High Income Countries but not so much for LMICs. The department of Medical Instruments & Bio Inspired Technology at TU Delft is currently working on a solution to produce a vessel sealing system which is safe and reliable to be used in LMICs. Electrosurgery is a type of surgery where high frequency alternating current is used to obtain a desired tissue effect like cut, coagulate, desiccate and fulgurate by converting electrical energy into thermal energy. An Electrosurgical unit is a generator which provides energy for many such surgical procedures and is available in every hospital. The aim of this project is to provide an additional module which can be attached to the ESU and generate energy of a bipolar vessel sealing system. The module will have a simple circuit design for easy maintenance and will be made of easily available, replaceable and inexpensive components. This will provide a possible solution to use bipolar vessel sealing in low cost setting. The list of requirements for the circuit of this module is collected from technical details in user manuals and experimental studies for both conventional ESUs and bipolar vessel sealing systems. It also determined the input and output characteristics of the module. The circuit design of the module is based on the block diagram of a common ESU and similar components have been used to establish a connection. The circuit was designed and simulated in a software and the outcomes were matched to the output of a bipolar vessel sealing system already in use (LigaSure vessel sealing system).Further investigation and research are required to make this module functional for clinical applications as the module does not perform all the functions of a bipolar vessel sealing system, but it does fulfil the basic purpose for which such a system is used in electrosurgery.

Baseball pitching is a movement wherein an external valgus moment around the elbow joint regularly causes an ulnar collateral ligament (UCL) injury. A proven relationship between the muscle activation around the elbow joint and its capacity to compensate for the external valgus moment during a baseball pitch allows predicting the likelihood of a UCL injury within pitchers in the future. The present study establishes the generic muscle activity around the elbow joint during a fastball baseball pitch to investigate the capacity of the muscles to compensate for the external valgus moment actively and thereby prevent a UCL injury. Six uninjured, experienced recreational adult pitchers, participated in this study (age: 25 ± 2 years; body height: 188 ± 10 cm; body mass: 77 ± 15 kg). 2000 Hz surface ElectroMyoGraphy (sEMG) was used to measure the muscle activity around the elbow joint in 15 fastball pitches for each participant. Before the pitch measurement, participants had to perform maximum voluntary contractions (MVC). The signals were corrected to an electromechanical delay of 50 ms and normalized to either MVC, or to the maximum of the signal itself. After that, the mean values were calculated for the instance of foot contact, maximum external rotation and ball release separately over the participants. A repeated measures ANOVA was performed to observe whether the mean activity is significantly higher at maximum external rotation compared to the moment of foot contact and ball release to compensate for the peak external valgus moment. Significant peak activity was found at maximum external rotation for all muscles, compared to the instance of ball release. The parallel activity of the flexor pronator mass and m. pronator teres at maximum external rotation enhances a compensating effect to the external valgus moment by its directly counteracting tension. Furthermore, the results support a co-contraction between the flexor pronator mass:extensor supinator mass and m. triceps lateral head: m. biceps brachii muscle pairs to compensate for the external valgus moment by a compression force to the elbow joint. The generic function of the m. anconeus in the fastball baseball pitch is still debated due to the inconsistent results over the different pitchers in this study. This study provides evidence that the muscles around the elbow joint can compensate for the external valgus moment during a fastball pitch. These results provide possibilities for using sEMG to assess the muscle activation pattern of individual pitchers as support to predict and prevent UCL injuries in pitchers in the future.

Sensors are extremely valuable to this world. Without sensors, we would not be able to live as we do in this data-driven environment. Therefore, finding new ways to measure the matter around us is a continuous process. In this work, an addition to the new sensors is attempted, using materials that can withstand the most extreme circumstances. This work describes the process of designing, simulating, producing, measuring and validating a pressure sensor based on LPCVD Silicon Carbide. The created sensor should be modular and back-end-of-line compatible. In addition, the sensor should measure pressures from 80Pa up to 1MPa at temperatures from room temperature to 600°C. Because of a favourable reaction to high temperatures, a capacitive sensor type that uses a sealed membrane for absolute pressure measurements is chosen. Due to the large pressure range, the design has been split into three distinct parts, each with its specialised pressure range. A low-range for 80Pa to 100kPa, a mid-range sensor for 100kPa to 300kPa and a high-range sensor for 300kPa to 1MPa. To compensate for the nonlinearity in the device, two approaches are taken. One method splits the bottom electrodes, generating a more linear output with the correct division. This approach is used for low-and-mid-pressure devices. The other approach uses touch mode to decrease nonlinearity. After the membrane touches the bottom contact, a linear range is found. This approach is taken for the high-pressure device. A flowchart has been developed based on the necessary layers to create the sensors. Using this flowchart, masks have been designed. During production, the process was adjusted, as delamination of the dielectric layer was observed. In addition, because of difficulty with sealing, the membrane is thicker than the original design. During production, buckling of the membranes was observed. This causes the sensors to behave differently compared to the simulations. One effect the buckling may have caused is the reaction to temperature. This is opposite to the simulations. In addition, subjecting the sensors to a vacuum also causes behaviour opposite to what was intended. When high pressure is applied, the sensors do work as intended. Due to the design alterations and buckling effect, the sensors are less sensitive to pressure than intended. The best sensor has a sensitivity of 0.025 f F/100Pa compared to the designed 0.3 f F/100Pa. However, the output of the sensor is linear without needing the designed compensation techniques.

ECG signals captured almost always have motion artefact noise. This noise arises due to relative motion between the ECG electrode and skin. To remove this noise a reference signal is required that correlates to the noise. This thesis presents the design and test results of a prototype system that incorporates various motion sensors into an ECG electrode and finds correlation between the motion artefacts and motion sensors.

Biofuel sensors for measuring the ethanol and gasoline concentrations in bio-ethanol blends, have been studied world-wide and currently used in engine management in Flex-Fuel cars fabricated by amongst others, Ford Motor Company. However, water that results from ethanol sugar cane is inevitable present in the ethanol blend and requires a sensor that is capable of measuring the full ternary ethanol/gasoline/water compostion. This thesis presents design of biofuel sensors, which can be used for the determination of compositions of ternary liquid mixtures of ethanol, gasoline and water. Firstly, the technical background and societal relevance of this thesis are given. Subsequently, the different physical domains are introduced that are in principle suitable for liquid composition sensing, such as the electrical, the acoustic, the optical and the thermal domains. As a next step, the thermal domain was selected with injected heat flux, J_h, as the through parameter and the resulting temperature difference, ∆T, as the across parameter. The basic principle of thermal impedance spectroscopy by frequency scanning was presented. Next, the thermal equivalent circuit model was used to simplify the thermal problem by transferring the thermal issue into an electrical topic. The main design challenge is to have the heat injected into the liquid rather than the substrate and to have a temperature-difference measurement not affected by the presence of the thermally conductive substrate. Different design properties such as heater, sensors, doping level, heat efficiency improvement and thermopile optimization, are explained in detail. After the interpretation on design properties, the fabrication process is introduced in detail and followed by the fabrication results. Finally, measurement results were obtained and used for validating the simulations and model and for drawing the final research conclusions.

Wirebonding is an interconnection technology used to connect a chip to its LED package. It is currently not well understood which wirebond characteristics are best to tailor to prevent the failure of wirebonds. The focus of this thesis is to understand the physics-of-failure of wirebonds via an experimental approach. Therefore, an experimental setup is designed which can accurately measure the resistance of the wirebond samples by four-wire resistance measurements. Furthermore, Finite Element simulations are done to understand the physical nature of wirebond failure better. Gold wirebonds with different loop geometries have been designed and made which are then subjected to temperature cycling. It is found through 4-wire experimental resistance setup that when a significant increase in resistance is reported, wirebond fatigue is imminent. Coffin-Manson based Finite Element simulations show that stresses at the neck are higher than at the heel. In retrospect, when the wirebond samples are encapsulated in Silicone, there is an increase in the stresses at the heel.

The prosthetic eye is created to help people who have lost an eye. The eye itself can only improve the appearance but without any optic function. In order to optimize the appearance, a prosthetic eye with a pupil that can dilate and contract according to the light level, just like the natural eye, is desired. The primary goal of this work is to develop and characterize a dilating pupil based on electrowetting. A droplet of an aqueous solution acts as a pupil. Electrowetting-on-dielectric (EWOD) has become one of the most popular tools in variety of applications, from microfluidics to electrowetting displays. This thesis presents the design of a low-voltage electrowetting one-pixel display which can act as a pupil. Decreasing the maximum actuation voltage is the main objective and challenge of this project. Different methods to achieve this goal are presented in the thesis, including using dielectric materials with better dielectric properties and using electrowetting liquids with lower surface tension. Ways to minimize the effect of gravity are also investigated. Droplet-based simulations are introduced by two methods. The simulation results are used to sustain the design process and for comparison with the measurement results on the real devices. According to the theoretical background and simulations, a test device is designed and fabricated in the cleanroom of EKL, TU Delft. The fabrication details are described in this thesis. Finally, measurements on the fabricated device are performed under different conditions. The results are shown and discussed in the final conclusions. In general it can be said that an electronic dilating pupil based on EWOD seems possible. Some recommendations for the future improvement are made.

This work presents a type of low noise amplifiers (LNA) that are used for ultrasound imaging systems. To account for the attenuating nature of ultrasound echo signals, a so-called time gain compensation (TGC) circuit is required. By increasing the gain over time, the output dynamic range is decreased, while the switching artifacts are suppressed by the continuous gain control. The proposed work combines the LNA structure with TGC functionality. This is done, such that the first component in the ultrasound receive chain does not need to be able to handle the full dynamic range of the input signal. The goal is to reduce die area and power consumption costs compared to systems that utilize separate LNAs and TGCs. The combined TGC-LNA consists of a transimpedance amplifier (TIA) with an exponentially-varying feedback resistance. As the feedback network and feed-forward path are separately designed, the design of the TGC functionality and low noise functionality can for a large part be independently designed. The TGC functionality is implemented by an exponentially-varying feedback resistance. This is achieved by means of implementing triode transistors as voltage-controlled resistors. Three branches with differently sized triode devices are required to obtain the full gain range of 40 dB. A two-stage telescopic amplifier realizes the loop amplifier. The bias current of the first stage is a linear function of the total feedback resistance to create a constant unity-gain bandwidth in a power efficient method. Realized in 0.180 μm BCDMOS technology, the combined TGC-LNA amplifies the signals from a Capacitive Micromachined Ultrasound Transducer (CMUT) with a center frequency of 7.5 MHz. The total achieved gain range is 40 dB where the gain varies during a receive period of 100 μs. During the receive period the total harmonic distortion remains below -44 dB and the noise floor is 1.12 pA/√(Hz) at the highest gain setting. Drawing 5.5 mW from a 1.8 V supply and requiring approximately 0.01 mm2 die area, the proposed TGC-LNA provides a new method for reducing power consumption and area costs for miniature ultrasound applications.