Conventional techniques for audio monitoring, including Passive Audio Monitoring (PAM), often call for the use of environmentally unsustainable and challenging equipment. This among other limitations can disrupt the very environment that is meant to be studied and may also limit the ability to observe an ecosystem in its natural state.

This thesis explores the possibility of a passive wireless biodegradable microphone for the purpose of audio monitoring in fragile environments. This project introduces the "The BioThing - A biodegradable microphone for monitoring biodiversity".
The BioThing uses a biodegradable material, to address the current challenges of state-of-art monitoring techniques. The design utilises a resonant cavity to function as a listening device through the implementation of the backscatter wave modulation technique and with a primary working resonant frequency of around 1.7 GHz.

This report presents a detailed analysis of the device's design and function to optimize its geometry for various frequencies, operational ranges, and functionalities by investigating the effect of critical parameters such as the variable capacitances namely the distance between the diaphragm and the tuning post, and the distance between the tuning post and the antenna. Additionally, it also analyses the effect of device geometry on resonance properties by investigating the impact of parameters such as tuning post height, membrane thickness, and cavity height. The report also investigates the possibilities for device enlargement for long-distance operation and device miniaturisation to facilitate faster degradation. This optimization process aims to achieve improved performance, ultimately leading to a more effective listening device. A prototype was fabricated using commercially available Zinc and plant-based resin.

This research works towards a new generation of ecologically sustainable audio monitoring equipment that will allow a deeper insight into the soundscapes of fragile environments without disturbing the ecosystems.

Organ-on-Chip (OoC) is a technology that aims to increase the efficiency of drug development processes and organ models by engineering well-defined cell culture environments. Physiological relevant mechanical, chemical, or electrical cues provide in vivo-like microenvironments for realistic cell maturation. Biodegradable technologies have gained attention for the development of novel OoCs by integrating transient features to the culture platforms imitating the ever-changing environment inside the human body. Current efforts to replicate durable brain tissue models from organoids are limited by the lack of sufficient vascularisation introducing cell necrosis inside the 3D cell culture.
This report presents the design and fabrication of a 3D-printed OoC-platform that combines two independent cell protocols for a Vessel-on-Chip and a cortical brain organoid. The microfluidic chip is embedded with a biodegradable membrane, that separates the two cell cultures for a strictly defined time period. The membrane, composed of bayberry wax, lanolin, and carbonyl iron particles, enables the controlled opening via alternating magnetic field exposure. The thermal behaviour of the membrane is analysed with DSC and the magnetic particles with a SQUID magnetometer. Inductive heating experiments determine the optimal composite composition and exposure profile to facilitate membrane opening and subsequent communication between neural and vascular cells. The integrated membrane proved to be successful during the injection and evacuation phase. This positive result paves the way for co-culturing two inherently different cell protocols on a single chip. This master project lays the foundation for collaborative efforts towards vascularised brain organoids-on-chip and showcases the potential of additive manufacturing and biodegradable materials in OoC technology.

Drug efficacy and side effects are significantly impacted by the first-pass metabolism, a sequence of events that occurs in the stomach and the liver after oral ingestion. Accurate prediction of this mechanism is crucial for a faster and more cost-efficient drug development process. Replicating the first-pass metabolism in vitro using standard cell culture techniques is challenging due to its complexity involving simultaneous transport and organ-organ interactions in both the gut and liver tissue. A more precise in vitro to in vivo translation of drug distribution, efficacy, and toxicity may be provided by organ-on-a-chip (OoC) models, thereby creating the ability to partially replace currently-used animal models. More specifically, gut-liver-on-a-chip models can aid with in vitro predictions of oral drug administration and the first-pass metabolism. Therefore, the aim of this thesis was to develop an OoC system that could accommodate both intestinal and hepatic cell sources. A hollow fiber membrane (HFM) as a cell scaffold was a critical component of the chip design in order to more accurately reproduce the three-dimensional native environment of the cells. Additionally, the system would need to exhibit the ability to be interconnected quickly and easily, thereby creating the possibility to develop a MOoC system in a plug-and-play manner in a later stage of development, enabling the ultimate realization of organ-organ interactions.

Airspeed information plays a crucial role in the takeoff, flight, and landing processes in animal flyers and aerial vehicles. Among the aerial vehicles, Flapping Wing Micro Air Vehicles (FWMAVs) represent the novel engineering approach of learning and mimicking animal flyers in the past two decades. A few prototypes of various sizes and functionalities of FWMAVs have been developed by MAVLab in the TU Delft Aerospace department since 2005. For these small and lightweight platforms, stable control under disturbances remains a challenge, and could further benefit from integrating effective airflow sensing into control system design.

Current commercial products are either not suitable due to size, weight, and power (SWaP) restrictions of the drone platform, or have very limited low-speed sensitivity. Therefore, to facilitate this, this thesis aims to develop a MEMS-based capacitive airflow sensor for a miniaturized and low-power implementation. Inspired by the filiform hair structure of arthropods, the sensor design comprises two key parts: the hair structure, whose displacement is governed by the drag force induced by the incident airflow, and the sensing base, located at the hair structure's base, which translates the structural displacement into a change in capacitance. The sensor exhibits the capability to sense airflow in one dimension and can be further adapted for omnidirectional sensing.

This thesis predominately focuses on the design and reliable fabrication of the sensing base. It is comprised of a suspended membrane supported by corner beams, supplemented by a pivoting dimple and anti-stitching dimples to facilitate robust hair movement and ensure optimal sensor functionality. The sensing base is fabricated at the TU Delft EKL cleanroom facility, equipped with sophisticated machinery that enables fabrication at micro and nano scales. Furthermore, the membrane suspension is achieved through the implementation of Vapor HF etching of a sacrificial layer beneath the membrane.

In conclusion, the devised sensors aspire to optimize flight control for FWMAVs within the constraints of SWaP, by drawing profound inspiration from the intricate workings of nature.

Cardiorenal Syndrome (CRS) is a multi-organ disease characterized by a reciprocal pathological interaction between the heart and kidneys during acute or chronic injury. Yet, a complete understanding of the underlying bi-directional pathophysiological mechanisms is lacking, hence obscuring effective diagnostic strategies, patient stratification and adequate administering of intervention therapies. Thus far, CRS has only been modelled in in vivo animal models, which are inherently limited in terms of experimental control and translatability of results to humans physiology. This underlines the need to develop more advanced in vitro models that accurately recapitulate the complex inter-organ cross talk responsible for the onset and progression of CRS. However, to date no such disease model system has been reported.

This project set out to design, develop and validate a microfluidic set-up, which would then enable the investigation of CRS in a three-dimensional environment. To that end, a theoretical framework covering all aspects related to Multi-Organ-On-Chip (MOoC) design was developed. This framework then formed the foundation for an extensive list of requirements to establish an ideal microfluidic set-up for a heart-kidney disease model. Various conceptual circuit designs were proposed and evaluated on the basis of the set requirements and their associated priority.

By executing feasibility studies, simulating computational fluid dynamics, designing specific organoid inserts and eventually setting-up the proposed microfluidic circuits, a better understanding of the technological and biological challenges to be addressed was obtained. Proof-of-principle experiments were promising, but more experimental iterations with a focus on in-depth biological tissue characterization are required to further evolve and fully validate the
proposed cardiorenal model. Pressing issues entail establishing physiologically relevant scaling ratios, reducing required medium volume and identifying the exact disease models to incorporate once the physiological organoid system is functional and has been validated.

This report entails one of two subsystems in a joint project to provide a web-based platform for smartwatch data acquisition, for applications in healthcare. In this work, we design and implement algorithms for human activity recognition using various machine learning approaches and test them on data acquired online as well as using our own developed platform. Together with the web-based platform, this provides a solid base for more research using data gathered from smartwatches. The human activity recognition is implemented first using a classical machine learning approach
with feature extraction and a random forest classifier. Next, both convolutional neural network and a recurrent neural network are implemented using Tensorflow [1]. We further perform several tests to investigate: (i) the optimal segment size with respect to classification accuracy, (ii) the effect of filtering and preprocessing on the classification results, and (iii) the best classifier for activity detection.

Modular quantum computer chip based on spin qubits in diamond will enable an increased connectivity, a high fidelity, and a low error-rate when the number of qubits increases. The high-quality diamond substrates have the maximum size in the order of mm2, preventing use of advanced semiconductor manufacturing line. Therefore, for a large-scale integration of qubits, there is a need for a wafer-scale diamond for scalable nanofabrication. Here, diamond-on-insulator structure will enable self-standing diamond structure by under-etching the insulator. Hydrophilic direct bonding of single crystalline diamond substrate on silicon is a promising approach.

In this research, a process is developed and optimized for hydrophilic direct bonding of (100)-oriented diamond on a low-temperature deposited SiO2 on silicon substrate. The process condition involves treating a (100) CVD diamond substrate in a Piranha solution. A 300-nm-thick SiO2 is PECVD deposited on a (100) silicon wafer which afterwards undergoes a surface activation process by oxygen plasma. The two substrates were contacted in an ambient without applying pressure, cooled, and then annealed. It should be noted that there was no pressure applied during the annealing. By die shear testing, a strong shear strength was measured and further elongating the Piranha cleaning time provided more shear strength bonding.

Engineered Heart Tissues (EHTs) are a valuable approach enabled by Organ-on-Chip (OoC) technology to model human cardiac tissue. These small microfluidic devices allow the culture and development of living cardiac cells in 3D structures, to reproduce tissue dynamics and functionality in-vitro, thus fostering the development of new and more precise models for human diseases and organs’ physiological response.
One of the most important gaps in this recent technology is the lack of integration of electronic devices in the platforms, such as electrodes for tissue stimulation or sensors for real-time monitoring of the tissue.

To cover this gap, a polymer-based platform with microwell and micropillars for culturing EHTs and measuring their contractile properties was developed in ECTM group at TU Delft. The contraction force exerted by the beating cardiac tissue, self-assembled around the micropillars, is quantified by measuring the displacement of the micropillars with spiral capacitive sensors embedded in the substrate. The force generated by the tissue corresponds to a capacitance change which is simulated to be in the aF range, requiring a high-precision, sensitive, and portable read-out circuitry.

The investigation and development of this readout electronics is the final goal of this Master Thesis. A literature survey about possible capacitive readout techniques was conducted to identify suitable architectures for measuring such small dynamic changes in capacitance. Two solutions available on the market (Smartec UTI and Analog Devices AD7746) implementing two of these architectures were chosen, tested, and characterised. Benchmark measurements with accurate laboratory instrumentation were performed, and noise figures of the two solutions were evaluated.
To allow the readout, EHT platforms with embedded sensors need to be transferred and assembled on a custom Printed Circuit Board (PCB): the viability of this challenging assembly process was evaluated. The multiple constraints deriving from such a complex project determined the development of a non-standard assembly process, which proved to be delicate and gave origin to multiple failure modes. Those were documented and analysed, to identify alternative or improved assembly procedures which need to be developed to fabricate reliable samples, since these weaknesses were identified as the most critical aspect at this point of the project.

The results obtained showed how the two solutions for the readout provided results in good agreement with more precise non-portable laboratory instrumentation, and promising noise figures. The platforms with embedded sensors were successfully transferred to the developed PCBs, and measurements showed good agreement with the simulated static behaviour of the sensors, thus providing a valuable proof-of-concept for the whole project.
The dynamic behaviour of the sensors was preliminarily investigated and characterized using nanoindentation tests, indicating the possibility to measure a linear relationship between the force applied and the difference in the sensed capacitance. Despite this good result, further tests need to be performed to verify it and to address some criticalities that were identified.
Cardiac tissue was cultured on platforms with integrated sensors and the biocompatibility of the entire system was proved. The behaviour of the sensors during biological measurement with cardiac cells is left to future investigation.

With the increasing demand in home-care service to provide early intervention at the homes of seniors suffering from early stage dementia, the Smart Teddy prototype offers a technological solution to disburden caregivers, to promote and track the health and conditions of the senior and to prolong their independent life at home. The Smart Teddy is a project founded in 2018 by a research team of the Hague University of Applied Sciences. It is an interactive, companion robot - disguised as a toy dog - that serves as a therapeutic promoter while simultaneously monitoring the quality of life of the senior with pre-determined indicators. It consists of a Teddy to provide the interaction with the user and a Base Station for data processing and charging of the mount-in battery of the Teddy. The Power Operations and Distribution group carried out research on and developed suitable solutions to supply power to the Teddy with rechargeable batteries, to integrate controlled wireless charging of the battery for user-friendliness and to provide a streamlined power distribution throughout the Smart Teddy’s system. Based on an iterated program of requirements and a power budget analysis on the set of installed electronics, a design is implemented for the power system of the Smart Teddy. A design sequence is followed consisting of four stages: (1) battery selection, (2) charger selection, (3) power conversion and distribution, and (4) safety and failure protection. A power system is developed for the Smart Teddy that is able to supply power with lithium-ion batteries with a battery life of at least 12 hours providing a battery capacity of 25.16 Wh. Thereafter, the installed batteries located in the Teddy can be charged wirelessly by placing the Teddy on the Base Station (a dog bed) to reinforce the less robot-like and a more natural look of the Teddy. Furthermore, this system ensures that all electronic modules with different operating voltages and current draws are provided with the necessary power specifications through power-sharing paths and the usage of power converters. Lastly, safety measures and failure protection methods are developed to ensure the safety of the user through the usage of fuses, switches and, cable and PCB management. The design has been verified using the appropriate verification methods where the program of requirements is used as a guideline and assessment tool. The Power Operations and Distribution is largely complying with the program of requirements and is performing according to the predetermined functionalities. Consequently, the power system of the Smart Teddy is integrated in a real, spatial prototype, namely in a toy dog (the Teddy) and its dog bed (the Base Station).

Currently, preclinical drug testing and disease modelling are based on static cell cultures and animal models that often fail at predicting the human pathophysiology. Alternatively, Organ-on-Chips (OoCs), dynamic microphysiological platforms, can be employed to recapitulate organ functions and mimic the cell's microphysiological environment. OoCs also promote the study of transport mechanisms and tissue barriers, such as the blood-brain barrier (BBB), a critical structure responsible for the regulation of the brain fluid microenvironment. Monitoring the ionic environment of the BBB and its variation due to the effect of drug testing is thus critical, indicating the need for integrated sensing elements. The rapid evolution of silicon technology and microelectronics has contributed to the development of field-effect transistors (FETs) for use as biosensors, ever since their first appearance in the 1970s. Such devices can provide real-time and label-free detection of target bioanalytes with high sensitivity. There are several types of FET-based biosensors based on different geometries and utilising various materials, but currently, no optimal consensus for a biocompatible FET-based biosensor with high sensitivity and reliability has been established. In the present thesis, floating gate FET-based sensors implementing flexible electrodes suspended on an optically transparent sensing area were designed and successfully fabricated for application on blood-brain barrier ion environment monitoring. Before the designing process, a thorough literature study on FET-based alternative solutions compatible with the BBB-on-chip application gave an overview of the available technology. It also indicated a lack of theoretical background behind the sensor's operation mechanisms. To face this issue, theoretical and simulation models were created based on the floating-gate MOSFET operation. Additionally, the electrical double layer (EDL) role, only included in models in the presence of a reference electrode is examined. The novelty of the sensor configuration lies with the implementation of an additional planar electrode in the sensing area of the OoC, tackling the issue of the external reference electrode use. Possible models describing the interaction between the additional electrode and the FGFET are created for comparison with experimental data. The novel sensor is designed aiming towards optimised sensitivity while also examining the effect of different configurations on the behaviour of the planar electrode. Dual-gate operation of the fabricated sensor in electrolyte indicates an increase of the output signal up to 16$\%$ compared to single-gate operation. In contrast to model predictions, the sensor does not operate in saturation mode, rendering the mathematical models ineffective. The simulation-based model is suggested for following applications after fine-tuning based on experimental data. Overall, a strong basis of the theoretical background was established, making ground for future studies.

The overarching goal of Engineered Heart Tissues (EHTs) is to develop functional 3D heart tissues in vitro with the potential to find drug targets, identify drug toxicity and predict the effects of the drugs in the body. This 3D model of the cardiac tissue consists of a bunch of cells, self-assembled around specific anchoring points the main aim of which is to support tissue formation. Although this model is very promising, still has to overcome an important drawback which is the lack of maturation of iPSC-derived cardiomyocytes (CM). This obstacle leads to limited recreation of the adult human cardiac tissue physiology. It has been shown that electrical stimulation of cardiac cells is one of the most important factors for cardiomyocyte’s maturation. Therefore, the principal goal of this thesis is to design and fabricate an electrical stimulator device and integrated electrodes in an existing EHT platform for electrical stimulation of cardiomyocytes. In the beginning, a literature study was conducted on different electrical stimulation methods and existing electrical stimulation devices for this purpose. For the first part of the thesis which was the design and fabrication of electrical stimulator, the electrical stimulation parameters that must be fulfilled by this device, were specified. Various hardware design approaches were studied in detail and compared before the design and implementation of the final idea. Simulations of the selected method using the LTSpice software tool were performed in order to study the behavior of the electrical stimulator design. The device is a 16-channel electrical stimulator that provides perfect rectangular biphasic pulses in the range of±15Vwith adjustable voltage amplitude, frequency and duty cycle. A user-friendly interface allows the user to select the desired channel of stimulation and the signal is distributed providing electrical stimulation to a total of EHT platforms. Therefore, this device was designed in a way to be connected with a second Printed Circuit Board(PCB) which hosts 16-EHT with integrated electrode chips. The 16-EHT holder (PCB)was also designed to suit in a 96-well plate, used by biologists for cardiac-cell culturing inside the incubator. The characterization of the electrical stimulator took place in the measurement room of the EKL lab. The results of the measurements verify the precision and efficiency of the electrical stimulator circuit as they are in excellent agreement with the simulations. The second part of the thesis includes the fabrication of integrated electrode-chips. The fabrication was conducted at EKL lab, in the Microelectronics Department of TUD using clean room microfabrication techniques. The selected electrode material was TiN due to its unique mechanical properties and the electrodes were fabricated on PDMS, encapsulated between two layers of polyimide. The main steps required for the integration of these electrodes in the existing EHT platform have been also carried out.

In the last few years organ-on-chip (OoC) has been emerging as a new method for more reliable research to screen the effects of new drugs on the body. This is a novel technology mimicking the in vivo environment of tissue cells, making it a more suitable candidate for experimentation than traditional 2D cell cultures. However, in order to ensure smooth and swift implementation of this technique, some issues must be addressed first. One of these issues concerns perfusion: most OoC devices require external equipment to provide the necessary dynamic flow that makes the OoC unique, so that cells experience continuous fluid shear and are perfused sufficiently. In this thesis a model of an on-chip electro-polymeric pump is designed for application on an OoC. From a background study the design aims are defined: a membrane actuated pump with a nozzle-diffuser channel providing pump action. The membrane is made from ionic polymer-metal composite (IPMC), a material that deforms under electric current which is produced at TU Delft with the intention to use it in OoC applications. Its low voltage operating range and its biocompatibility make it an excellent candidate for this. Furthermore, the nozzle-diffuser elements avoid the need for moving elements inside the channel, instead providing pump action based on a pressure gradient over the nozzle elements. Finally, three design aims are defined, being: high flowrate, high flow pulse and low flow rate and pulse applications, corresponding to various needs in the OoC field. A base model is designed using COMSOL Multiphysics software, using similar devices described in literature. The model consists of a combination of solid mechanics (for membrane movement), fluid mechanics (for flow movement) and a fluid-structure interaction module to combine the two. This model is then tested for a range of parameters, first independently and later in pairs. General conclusions drawn from these simulations include: - Between the membrane displacement and -frequency (which can both be varied after fabrication), the membrane displacement magnitude affects the output more significantly than actuation frequency - The membrane width is positively correlated with flow rate output and pulse amplitude - The channel depth is positively correlated with flow rate output, but only if the membrane displacement scales along with it - A long slender nozzle yields lower flow output than a short, squat nozzle - The results from this model are consistent with nozzle-diffuser theory, stating that nozzle resistance and membrane movement affect the flow most significantly. This leads to three designs according to the three application wishes expressed earlier. The pump is designed such that it can be manufactured on a silicon wafer using electronics cleanroom equipment. The combination with the process developed for IPMC provides a novel pumping mechanism that has the potential to fully integrate an important aspect of an OoC on-chip, greatly increasing user friendliness and allowing for wider implementation of this technology.

Graphene is an attractive material to be used for pressure sensors due to its thinness, electrical conductivity, and potential high gauge factor. One of the issues with processing graphene is the scalability, which is largely limited by the transfer process that is required for graphene deposited by chemical vapour deposition (CVD). In this work we employed a novel, transfer-free bulk-micromachining approach to realize graphene-based differential pressure sensors. The devices were successfully fabricated, and the samples were examined under Raman Spectroscopy, and electrically characterized. Further, pressure dependent measurements were performed for a dynamic range of 0 to 80 kPa of differential pressure and the corresponding change in resistance of the membrane was measured. The fabricated devices have a mean Gauge Factor of 2.80.

For this Master thesis the possibility was explored to use a monolayer of graphene as conductive layer, instead of sputtered titanium nitride (TiN), on 25 nm thick aluminium oxide and magnesium oxide membranes. These membranes will be used in a new and faster variant of a vacuum electron multiplier (e.g. the Photo Multiplier Tube (PMT)). These membranes should act as transmission dynodes, or tynodes, where electrons are multiplied while interacting when they travel through the membrane and leave the membrane on the other side instead of being multiplied by hitting the surface of a dynode, where secondary electrons are released on the same side. These membranes are constructed using insulators and can charge up, as more electrons leave the membrane than enter. To circumvent this issue a conductive layer is applied on these membranes. The advantage to use graphene over TiN as conductive layer would be that the maximum transmission electron yield is higher and occurs at a lower incoming (primary) electron energy due to the reduced total thickness of the membrane. In order to get graphene on the membranes a wet transfer method of graphene was used where a layer of Poly(methyl methacrylate) (PMMA) was applied to support and the graphene sheet and to make it buoyant.
The adhesion of graphene to alumina membranes proved to be very difficult and on many occasions the graphene was washed away during the removal of the polymer by acetone. The few remaining samples that were produced on both alumina and magnesium oxide membranes, where the conductive layer was successfully applied, had a lower transmission electron yield than the samples coated with a sputtered TiN layer. Sputtered TiN was used as conductive material in this project, before graphene was researched for this thesis. The reason for the lower yield is that the adhesion between the conductive graphene and the membranes was not good enough to conduct electrons vertically in the membranes causing them to charge up. One of the reasons for the poor adhesion is that the membranes are wrinkled and curved due to internal stresses that are caused by the production process. The graphene layer cannot follow these curves due to the way it is applied and only makes contact at the tops of the wrinkles. The primary electron energy, where the (lower) maximum yield was observed, was higher than samples with TiN, while the expectation was that graphene as the conductive layer would lower this energy, due to the reduced thickness. These observations lead to the conclusion that graphene is not a viable replacement for TiN as the conductive layer on these membranes.
The use of TiN deposited by Atomic Layer Deposition (ALD) instead of sputtering was also tested. The samples produced with this method conducted electrons well enough to prevent charging effects in the membranes. The added benefit is that the TiN can be deposited with the alumina layer in a single ALD run and that its thickness can be controlled more precisely. The positive results make ALD TiN a viable replacement for sputtered TiN, but more research should be done to find the minimum thickness of this layer where it is still conductive enough to prevent charging of the membranes.
In order to circumvent the abovementioned adhesion issues, a transfer-free method was developed to create graphene-alumina membranes, where the alumina was deposited on the graphene through ALD, instead of transferring graphene on the alumina. Since copper is used as a catalyst to grow the graphene, this put a lot of constraints on suitable wet etching techniques. This resulted in chemical baths where the temperature control was not ideal, which lead to much longer silicon etch times and loss of wafers. Near the end of the process a silicon oxide layer needed to be removed, but this step was most likely not performed correctly, leaving a thin layer of silicon oxide that blocked chemicals that should remove a deeper layer to release the membranes. Further testing of these samples fell out of the scope of this thesis and could be researched in the future. In conclusion, it is advisable to etch the silicon earlier in the process when the copper has not been deposited yet. In general the flowchart of this process needs a revision.

Silicon accelerometers used in the automotive industry should be improved in resolution and accuracy. Exploiting quantum effects in diamond to improve sensing accuracy is a popular technique for nanoscale sensing applications. This thesis will present a new design concept for an accelerometer using these quantum effects for sensing on a macroscopic scale. This sensor can sense these forces with a resolution of 6g and a range of 120g. In measurement time it is slower than current sensors, but our sensor can still serve as a prototype to be improved in the future.

Nanocatalysis has received considerable attention in the scientific community due to their superior reactivity compared to their macro-sized counterparts. MEMS nanoreactors allow scientists to view these reactions in-situ. This opens up doors to finally understanding the underlying mechanisms of the nanocatalyst's effectiveness, which may eventually improve our every day lives.

This thesis focuses on the viewing port of the device -- the electron-transparent window (ETW) -- and how they can be improved for future generations. From scattering theory, it was determined that the best way to improve the imaging quality of current ETWs was to develop thinner ones. Two questions were then asked: can a thinner ETW be integrated into a nanoreactor process? If so, how will it affect the mechanical strength of the ETW?

Aluminum oxide (alumina) was chosen specifically because of its deposition method, atomic layer deposition (ALD). The characteristics and material properties of ALD alumina were assessed and it was determined that they are suitable for ETW applications.

Using ALD alumina presented a few challenges in its integration into nanoreactors, especially the use of vapor hydrogen fluoride. ALD alumina ETWs were able to be successfully integrated into a nanoreactor down to 5 nm thick. The 5 nm alumina ETWs are able to withstand a pressure difference at least 0.75 bar, however they were not able to survive inside a TEM as they disintegrated immediately under the electron beam.

Alumina ETWs that are 10 nm were able to be imaged in a TEM. These windows were tested in a transmission electron microscope (TEM) and scanning electron microscope (SEM) to showcase the improved electron-transparency.

The ultra-thin ALD alumina ETWs can improve the imaging quality of nanoreactors, due to their lower thickness compare to current nanoreactors. The successful release of 5 nm membranes may also be useful for other applications, such as sensors.