Engineering Science - Undergraduate Honours Theses

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Developing a Reusable Aptamer-Based Biosensor for Interleukin-6 with a Quartz Crystal Microbalance

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2021-12-24
Abstract: 

Cytokines are a general class of proteins involved in inflammatory response, and abnormal concentrations of cytokines in humans have been linked to a number of diseases. Aptamers are single-stranded DNA or RNA oligonucleotide sequences developed using in vitro selection that can selectivity bind with specific cytokines. These aptamers can be covalently linked to a number of surfaces in order to measure cytokine concentrations. Aptamer-based biosensors have been shown to be a legitimate alternative to the current antibody-based sensors, showing more sensitivity while being easier to produce and more important, reusable. This thesis demonstrates an aptamer based sensor using a quartz crystal microbalance system for the purpose of detection the cytokine Interleukin-6 (IL-6). The aptamer, attached to a silicon wafer with gold electrodes, binds with the cytokine exposed to it, changing the crystals resonant frequency which is measured by the system, from which the mass of cytokine can be determined. This thesis explains the surface functionalization and aptamer attachment process as well as a number of experiments testing the sensitivity, selectivity, and reusability of the sensor. 

Passivated Covalently Functionalized Quartz Crystal Microbalance for Reusable Detection of Small Proteins

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2021-12-21
Abstract: 

This thesis outlines the potential of quartz crystal microbalance (QCM)for small protein detection. Such small protein is a signaling protein named cytokine which is related to various diseases. Currently used biosensors are an extension of the aptamer-based sensor described in Yue Ling’s thesis 

Covalently functionalized QCM crystals were tested with Tumour Necrosis Factor Alpha (TNF-α) on three aspects, for instance, sensitivity, reusability, and selectivity. The detection method was injecting solution contained target cytokine into a chamber with QCM crystal and comparing the frequency difference before and after the introduction. For the selectivity test, another cytokine, Interleukin 6(IL-6) was presented, and frequency shift should not be observed. To reuse the biosensors, they were rinsed with 7M urea and phosphate buffered saline, respectively.

In the sensitivity test, the biosensors had successfully detected 0.1 ug/ml of TNF-α. The modified urea wash method also demonstrated its reusable for further experiments. Whereas the biosensors have shown response to the nontarget cytokine, IL-6. To alleviate response to nontarget cytokine, the functionalization process was modified by adding a blocking agent, ethanolamine. This chemical substance will forma passivation layer on the surfaces of the biosensors resulting in the reduction of nonreacted surface groups (GOPS-CDI) binding. The following experiments with these passivated QCM crystals have shown improvement in selectivity, and the sensitivity of the crystals was not impacted. Rather, the key factor of maintaining the sensitivity is related to the aptamer concentration on the crystal surface.

Further studies on the selectiveness of biosensors will be needed to examine the effectiveness of ethanolamine with a relatively consistent amount of aptamers on the QCM crystal.

Document type: 
Thesis
File(s): 

Development of Screen-Printable Flexible Circuits on Fabric Using Commercially Available Conductive

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2021-12-20
Abstract: 

Over the past decades, electronics and silicon manufacturing have grown rapidly. Alongside this, the capability of integrated circuits (ICs) has significantly increased; modern electronics are becoming smaller and faster while also consuming less energy. Though there have been some developments with wearable devices and sensors, most consumer electronics still use printed circuit board (PCB) fabrication methods, making them inflexible or limited in flexibility, and thereby difficult to integrate into the fabric of clothing. 

 

This thesis outlines a screen-printing method that utilizes inexpensive, commercially available conductive ink laid over fabric to make an entire functional and flexible printed circuit which will be referred to as Screen Printed Circuit (SPC). To achieve this goal, all designed are modeled in electronic Computer Aided Design (CAD) software. This task presents several challenges, including figuring out the physical properties of traces such as their resistance, clearance limit, resolution, ink penetration depth, and stretchability. Knowing these parameters, one can model and make useful and relevant electronic circuits. This thesis validates performance of this methodology by constructing and testing an array of passive low-pass and high-pass filters. The method is evaluated by several qualities: accuracy; solderability of the inked traces; ability to make custom resistors and capacitors; and durability. These measured quantities are compared with their theoretical counterparts. 

 

Each developed SPC functions as intended and performs to within reasonable range of theoretical values across all important metrics. Further, the circuits are very flexible and perform as expected after being normally handled. This demonstrates that one can use these printed circuits in most low-speed applications where traditional (inflexible) PCBs are currently used, with minimal changes to design flow. Importantly, these printed circuits also demonstrate their ability to easily integrate into clothing, where PCBs are not typically appropriate. 

 

It should be noted that the benefits of these flexible circuits do not come without some drawbacks. The conductive inks used in the traces have markedly higher resistivity than copper PCB traces, which decreases the power efficiency of the circuit. As well, the traces are brittle and show cracking after even moderate stretching, which further increased resistance. Future research should focus on potentially combining the thesis results with more complex and expensive methods that show improved reliability and deformability. For example, the developed methods could be combined with conducting threads or customized conductive polymer composites. Finally, developing additional custom resistors and capacitors would increase the range of circuits one can build with this method.

Document type: 
Thesis

The Effect of Elevation on Single Event Upsets in Digital Imagers

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2021-12-15
Abstract: 

Cosmic radiation causes transient errors in microelectronic devices, known as Single Event Upsets (SEUs). These errors are most common in space-borne electronics, however terrestrial electronics experience the same errors, to a lesser degree. SEUs can be difficult to characterize in most integrated circuits, however, in digital imagers they cause defects which appear as unexpected bright pixels that are temporarily present in a series of images. To detect them, a sequence of long exposure, dark-frame images is recorded and then during analysis pixels which appear bright in one photograph but dark in the images immediately before and after are flagged. Just as the effect of SEUs is more prevalent in space, a rise in elevation on Earth can increase the frequency of SEUs by a noticeable amount. In this thesis, I will perform a series of experiments to understand the relationship between SEUs and elevation. Using DSLR cameras, images will be recorded at elevations ranging from sea level to approximately 1200 metres above sea level. The quantity and charge distribution of the SEUs will be extracted from the photographs and compared to the elevation.

Document type: 
Thesis

Preliminary MEG Study of Emotional Face Processing Among Children

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2021-08-22
Abstract: 

Human social interaction heavily depends on understanding faces, as they carry information about age, gender and emotions. Extensive research has been performed to understand face processing in adults and in children using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). However, there are far fewer studies using magnetoencephalography (MEG) and only a small handful that study children. The data from this study was one of the first that aimed to find the neurological pathways of face processing of children in the MEG space and additionally aimed to examine the differences in emotional facial presentations. We used MEG datasets from 10 healthy children in the age range of 9 to 16 years old collected during the presentation of static faces with different expressions (neutral, anger and fear) and objects (butterfly, fish and guitar) as control states. The data was preprocessed and an event-related beamformer was utilized to localize the millisecond timescale of activity of the brain processes during the face stimuli and during the object stimuli. We observed activity consistent with the face sensitive M170 event-related  field component with a group average amplitude of 10nA peak and 171 ms post stimulus.  This component localized to the occipital-temporal-parietal region in the right hemisphere consistent with either the fusiform face area (FFA) or the posterior superior temporal sulcus (pSTS).  To our knowledge, this may be one of the few studies that demonstrate localization of face sensitive areas in children using an event-related beamformer approach for MEG. 

Document type: 
Thesis

A Novel Exoskeleton Prototype Based on the Use of IMUs to Track and Mimic Motion

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2021-07-18
Abstract: 

This thesis presents the development of a person-portable exoskeleton prototype which is designed to be controlled with Inertial Measurement Units (IMUs). It utilizes Euler angles calculated by the IMUs to track the rotation of the user’s forearm and then performs the same rotation, mimicking the user. Special care is taken with the prototype’s control algorithm to ignore changes in Euler angles caused by non-forearm rotations, which can otherwise cause erroneous prototype movements. The prototype is successful in demonstrating this method of control but does require the user to follow some specific guidelines to work at maximum effectiveness. Future iterations of the prototype can be easily improved by replacing some of the commercially available materials with more specialized ad-hoc products.

Document type: 
Thesis

Deep Learning for Satellite Image Analysis

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-12-18
Abstract: 

Deep learning architectures have the potential of saving the world from losing football fieldsized forest areas each second. These architectures possess large learning capacities when compared to conventional machine learning architectures, and thus are trained on sizable data-sets to efficiently extract both coarse and fine features from various image scenes. As a result, they can provide crucial information that is needed to manage the deforestation process and its consequences on the environment and ecosystem more effectively. This thesis outlines the two deep learning based systems designed for satellite image analysis. The first system analyzed satellite images of the Amazon, and the goal was to interpret the image content by providing a set of labels that best describe it. The highest performing architecture was able to achieve a score of 92.886% while a combination of several high performance, yet uncorrelated, architectures increased the overall score to 93.070%. This result is only 0.248% lower than what current state of the art algorithms achieved on the same task. The second system was designed to detect the presence of clouds in Landsat 8 images by analyzing small chips within each large image. This system produced cloud masks, which were then compared to the corresponding ground truth cloud masks obtained from the provided images. The predicted cloud masks were able to achieve an average score of 92.931%, which is very high for the given accuracy measure.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Ivan V. Bajić
Department: 
Applied Sciences: School of Engineering Science
Thesis type: 
Honours Bachelor of Applied Science

Implementation of Active Noise Cancellation in a Duct

Author: 
Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2013-11-15
Abstract: 

An Active Noise Cancellation (ANC) system is implemented in real time using both feed forward LFXLMS (Leaky filtered-X least-mean-square) and feedback LFXLMS approaches for adaptive filtering. ANC algorithms are implemented on a ADAU1446 evaluation board and tested in terms of sound cancellation in a duct. The hardware and software interfaces required for the system are explained in detail. A test bed is developed to measure the performance of sound cancellation. Results are analysed in detail and recommendations are made for future research work to improve the performance of the system and to realize noise cancellation in 3D space.

Document type: 
Thesis
File(s):