Introduction:
High impact respiratory conditions are common amongst preterm infants. Measuring the electromyogram of the diaphragm (dEMG) is a very promising technique to accurately measure respiratory state. However, the currently used Ag/AgCl electrodes are reported to be big and thick, making them less suitable to measure dEMG in preterm infants. Therefore, the aim of this study was to create a prototype for a thin, flexible electrode that could measure dEMG in preterm infants with at least the same signal quality as the currently used Ag/AgCl electrode.
Methods:
To do so, design requirements and wishes were set. Literature and three tests were used to assess whether a certain prototype met the design requirements. If one of the design requirements was not met, an iteration cycle was started and the prototype was redesigned. With the final version of the prototype, a proof of principle test was performed, where dEMG measurements were conducted on a healthy female adult using the prototype and the standard Ag/AgCl electrodes simultaneously.
Results:
The final design was created from two layers of Shieldit conductive fabric ironed onto cotton and one insulating layer of TPU. These layers were connected to a shielded cable by weaving the copper wire through the fabric.
Ultimately, not all design requirements were met. The frequency plot of the final prototype still showed a peak at 50 Hz, indicating insufficient shielding from electromagnetic interference. However, the final prototype was indeed dry, thinner, and more flexible than the Ag/AgCl electrode. The RMSE value for the prototype (0,5984 mV) was smaller than that for the Ag/AgCl electrode (0,5998 mV), although the opposite was true for the SD (prototype: 0,1031 mV, Ag/AgCl: 0,0316 mV). In addition, it was proven that the final prototype could be used to measure dEMG in healthy adults. The breathing frequency measured by the final prototype was equal to the breathing frequency measured by the Ag/AgCl electrode, whilst showing no significant difference in amplitude of the peaks of the breathing curve (p = 0,0830).
Discussion:
Design improvements could be made by eliminating the 50 Hz peak, decreasing diameter even further, creating a new version where the cable could pivot around the electrode or exploring wireless options.
Conclusion:
In this paper, it has been proven that a textile prototype is well capable of measuring dEMG in humans and offers several improvements over the Ag/AgCl electrode. ... Read more

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. ... Read more

Spin-transfer-torque magnetic random access memory (STT-MRAM) is regarded as one of the most promising non-volatile memory (NVM) technologies, which has the potential to replace the traditional memories in the modern memory hierarchy. Due to some advantages such as non-volatility, fast access speed, low leakage power and high density, more and more research attention is being paid to STT-MRAM. To enable the mass production of STT-MRAM, high-quality and cost-efficient test solutions are the prerequisites. In this thesis, the comprehensive investigation for testing interconnect and contact defects in STT-MRAMs will be presented. The complete defect space for interconnect and contact defects in STT-MRAMs is systematically defined, which are modelled as linear resistors. All theoretically possible faults are defined in a fault space, followed by a methodology to validate these faults under inter-cell magnetic coupling in the presence of defined defects. In this way, accurate fault modelling is performed to guarantee the occurrence of realistic faults in STT-MRAMs. We observed the specific STT-MRAM fault model—passive neighborhood pattern sensitive fault (PNPSF). Based on the fault validation results, an effective march test algorithm(7N) is proposed for interconnect and contact defects in STT-MRAMs. ... Read more

Every year, nearly five million people undergo knee, making it one of the most common orthopaedic procedures. Sport-related injuries and age-related diseases are the major causes that lead to a knee operation. To recover mobility, stability and muscle strength, the person must go through a post-surgical rehabilitation program.
The price of these physiotherapy sessions increases the already high medical cost of the treatment. Additionally, it is a long and repetitive process that might make them lose motivation and discourage them before finishing the whole program. It is also inaccessible for some people, who live far away from a hospital or rehabilitation centre or in areas where the public healthcare system is saturated. As a result, many people abandon their rehabilitation programs and never recover the pre-injury state.
In this project, we propose the use of a game controlled using Inertial Measurement Units to improve the rehabilitation process. The game would reduce the costs of the rehabilitation, make it accessible for everybody and increase the motivation of the patients. ... Read more

Since the outbreak of SARS-COV-2, various virus inactivation techniques have been applied to suppress the spread of virus. Ultraviolet exposure inactivation is an efficient approach to inactivate virus, within UV band, UV-C with comparatively higher energy. UV-C has been proved to inactivate viruses efficiently, while to figure out efficient inactivation approach, virus reduction rate as a function of UV-C wavelength with different viral sensitivity and quantitative exposure dose should be measured through experiments.
On the one hand, miniatured, energy-efficient and fully-customized UV-C light-emitting diodes (LED) offer possibility of switching wavelengths and adjusting quantitative optical properties, on the other hand, UV-C LEDs have been produced with the latest technology based on Aluminium gallium nitride (AlGaN).

~\\Multifunctional UV-C LED Virus Inactivation Experimental Platform is a system designed with replaceable UV-C wavelengths, controllable light intensity and exposure time for quantitative virology experiments. The system has an initial design for standard virology experimental equipment which offers a new and consistent tool for virus researchers. The Inactivation Platform has been assembled and utilized to perform several Influenza A (ssRNA virus) inactivation experiments in order to obtain reduction rate as a function of UV-C wavelength and exposure dose with Germicidal Curve and Inactivation Curve respectively.

~\\After inactivation experiments implementation and result analysis, the inactivation mechanism on the basis of molecular dynamic research theory and simulation is supposed to be figured out. Due to the complexity of proteins in virus, the research focuses on Nucleic Acid Bases (NABs) as target genetic viral material. The absorbed ultraviolet energy results in ultrafast decay, including molecular electronic transition, virus structure variation (Dimerization) theoretically. The absorbed energy along the band is revealed with Absorption Spectrum, and the potential electronic transition depends on the initial structure NABs, together with inside chemical bonds. When absorbed energy populates the molecules to transition state, ultrafast decay takes place because of the existence of Gibbs energy of activation. In the light of molecular dynamic simulation, it proves that compared to ground state, excited state leads to lower standard Gibbs energy of activation, causing higher reaction rate (faster inactivation speed). ... Read more

As of 2021, the world economic forum deems cyber-security failures as one of the most potent threats to the world. According to a McAfee report, the cost of cybercrimes in 2020 reached nearly 1 trillion US dollars, which was around 50 percent more than what it was in 2018. Exacerbating the already mammoth financial implication of such a failure is the ever-growing diversity in cyber attacks. Side-channel analysis is one such attack type wherein the information leaked via the implementation of a cryptographic algorithm is leveraged to obtain secret data, rather than any weaknesses in the cryptographic algorithm itself. This leaked information, amongst others, can be in terms of power, EM radiation, or the time taken to perform a cryptographic operation. Countermeasures against such side-channel attacks aim at reducing the amount of information leaked via the side channels or reducing the correlation between the secret operations and the information leaked. Manufacturing the chip is often a prerequisite for evaluating the efficacy of such countermeasures, which is a costly and time-consuming process. Thus, the security evaluation of a design has a substantial impact on the design cost and the time to market. In case the design does not meet minimum security requirements, it has to be redesigned and manufactured, increasing not only costs but also the design time considerably. Hence, there is a need for pre-silicon leakage assessment tools that can provide designers a sense of certainty about the security aspects of their design. However, the existing pre-silicon leakage assessment tools are either deemed unreliable or too slow to be used to perform power leakage assessment, which is the problem this thesis aims to ameliorate. This thesis explores the use of generative adversarial networks (GANs) for generating synthetic power traces. Generative deep learning has been used in various domains like computer vision, audio, and even for medical data like ECG. GANs have been introduced in the context of side-channel attacks to enlarge the size of the profiling dataset for carrying out profiled side-channel attacks. In this work, we propose a robust methodology to condition and train GANs to generate power traces that can be used to carry out leakage assessment. This methodology can even be extended to support the design space exploration of countermeasures by providing reliable leakage assessment at design time. The generated power traces are not only indistinguishable but also as attackable as the real traces. The conditioning technique helps the GAN to generalize to various scenarios and the proposed framework provides a speed-up of around 140 times over traditional CAD methods to simulate power traces while maintaining their structure and accuracy. ... Read more

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. ... Read more

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. ... Read more

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. ... Read more

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. ... Read more

Approximately 15-20% of theworld population is aected by tinnitus, a hearing condition associated with phantomsound perception. A large number of suerers experience a severe level of tinnitus and they are not ableto conduct a normal life because they develop insomnia, depression, and distress.Extensive research has been made to study its pathophysiology and to nd a therapy. However, currently thereare no treatments that have demonstrated to be eective in modulating tinnitus or suppressing its related annoyancefrom a long-term perspective. What is known is that the patients exhibit abnormal electrical activityin multiple areas of the auditory and the central nervous systems. This is the reason why the focus of thescientists has shifted to multi-modal stimulation: multiple stimulations of equal or dierent nature (e.g. doubleelectrical stimulation or acoustic-electrical stimulation) are applied at the same time in the attempt to induceneuroplasticity and restore the normal electrical activity in the targeted areas. Multi-modal stimulation hasbrought signicant improvements both in terms of tinnitus intensity and distress, but the studies conductedare too little to derive conclusions. Stimulation sites, parameters, and patterns are some of the many issues thathave to be properly investigated.The challenge of this work is to design a portable multi-modal stimulator that is able to provide bilateral acousticand electrical stimulation simultaneously. The device works at the same time as an audio player and atranscutaneous electrical nerve stimulator, with the purpose of contemporaneously stimulating the auditorycortex and the autonomic nervous system or the dorsal cochlear nucleus through the vagal nerve or the C2nerve, respectively.Bi-modal stimulation is based on the random presentation of pure tones matched to the tinnitus frequency pitchcombined with two possible electrical stimulation waveforms: a novel one characterized by the superposition ofa low-frequency noise on a DC component ("noise + DC" stimulation) and the second one is burst stimulation.Both the electrical stimulations are current-driven and largely customizable due to the wide programmabilityof the stimulation parameters. The analog design is realized in such a way that two identical output currentsare delivered to the tissue, allowing for bilateral stimulation.The low power consumption and the small dimensions and weight of the device will permit the tinnitus patientto use it for several hours per day while performing his daily life without impairments. ... Read more

This research provide a proof of principle to use a sweat sensor system for real-time monitoring of medicine effectiveness in Cystic Fibrosis (CF) patients. CF is an autosomal recessive genetic disorder affecting mostly the respiratory, digestive and perspiration system. Patients with CF have dysfunctional chloride channels in their cells, due to mutations in both copies of the gene for the CFTR protein. The CFTR proteins are necessary for the production of mucus, a malfunction of the CFTR protein will result in tough mucus. In CF, a lack of functional CFTR prevents normal sodium and chloride absorption in sweat and leads to excessive salt loss. Due to increased sodium and chloride concentration in sweat from CF patients, sweat makes a good clinical body fluid to indicate the medicines' effectiveness. By measuring the chloride or sodium concentration before treatment with the medicine and after treatment, an indication of the medicines’ effectiveness can be obtained. In this study, a potentiometric screen-printed sweat sensor has been developed to monitor the medicine effectiveness in CF patients. The sensor consists of a reference electrode and ion-selective electrodes for measurements of chloride and sodium concentrations. Multiple prototypes of the sensor have been developed and evaluated on their performance. Furthermore, a read-out circuit with low leakage/bias currents and 8 channels is designed to increase the read-out accuracy and speed. Since the sweat volume during rest appeared to be too low for real-time measurements, a sweat collector was implemented with the sensor to increase the sweat sample volume during real-time measurements. Furthermore, a pilocarpine sweat stimulator has been designed and tested to artificially increase the sweat rate.
The developed system proofed to be a functional concept for real-time patient monitoring. In future research, the chemical structure of the membranes is the most important topic to be improved. Improvements in this field could extend the life-time of the sensor and would minimise the sensitivity differences between the sensors. Finally, the sweat sensor, collector and stimulator have to be integrated and minimised in one design to make a wearable device out of it. ... Read more

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

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. ... Read more

Biofuel sensors for measuring the ethanol and gasoline concentrations in bio-ethanol blends, have been studied worldwide and currently used in engine management in FlexFuel 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 composition.
This thesis presents the design of biofuel sensors, which can be used for the determination of compositions of liquid mixtures of ethanol and water, combined with the UV sensor, the ternary concentration problem of ethanol, water and gasoline can be solved.
Firstly, the technical background, societal relevance and the purpose of this thesis are given. Subsequently, the spectrum analysis of the infrared rang is analyzed, and the ranges of interests are found. As a next step, the technologies which can possiblely applied in our application are analyzed, after that the coupling methods are analyzed. Next, the physical model of the sensor structure is built up in two simuation softwares and it is simulated in detail. After the interpretation on design properties, the fabrication process is introduced in detail and followed by the fabrication results. Finally, measurement setups were built and used for validating the simulations and model and for drawing the final research conclusions. ... Read more

In this thesis,two essential parts of microspectrometer are designed, fabricated and measured. They are a hot wire of polysilicon with constant temperature profile that used as the IR light source, and the LVOF which is aimed at IR spectral range. In order to have the desired IR source, the hot wire should have temperature distribution as uniform as possible based on black-body emission. Thus, the thermal mechanics inside the hot wire is fully studied including heat generation, conduction, convection and radiation. The thermal energy is electrically generated by voltage and current source. While the heat loss causing non-uniformity on temperature is mainly induced by heat conduction between the hot wire body and substrate, and to surrounding air. For the first one, the geometry including the length, width and thickness, the resistivity profile of hot wire and the meander bridge at the end of hot wire body are designed. The meander bridge works as the connection and interface to substrate which to some extent determines the heat conduction through it. Moreover, it can bear tensile force induced by thermal expansion. Besides, the meander middle bridge is added to hot wire as well in some design plans for stronger mechanical stability. On the other hand, since the temperature on hot wire is significant related to air pressure due to heat conduction to surrounding air, all hot wires are designed to operate in vacuum environment. Finally, a bunch of hot wires with different geometry, resistivity and TCR are designed and fabricated. To design the LVOF aimed at IR band, the working schematics and properties of LVOF are firstly studied in depth. All factors such as reflectance, incident angle, cone angle and so on that might affect its performance which includes the most important transmittance are researched. The LVOF is also designed in different length and tilt angle. The case that the LVOF with the hot wire as IR source is paid special attention to. Eventually, the electrical property and optical performance of hot wire is measured in vacuum chamber by FLIR IR camera. So far, the hot wire that has best performance is the one comprised of array of short hot wires. The result is fully discussed and divergence between actual performance and design plan is analyzed from many aspects. ... Read more

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. ... Read more

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. ... Read more

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.
... Read more