Tyndall National Institute - Masters by Research Theses
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Item Analog mixed signal IC design for magnetic tracking in surgery: low area clocking for CT∆ΣM ADCs for in-vivo sensing(University College Cork, 2024) Ferro, Alessandro; Cantillon-Murphy, Padraig; O'Hare, DanielThe application for this work is an in-vivo sensor system for capturing magnetic signals used for tracking surgical instruments such as catheters in the body during minimally invasive surgical procedures. With the ascent of image-guided interventions, the precision in determining instrument pose has become paramount. The proposed system leverages low-frequency electromagnetic fields for magnetic tracking, ensuring non-ionising, line-of-sight-free measurements with millimetre-scale accuracy. The miniaturisation demands of electromagnetic sensors, crucial to this endeavour, necessitate dimensions less than 0.5 mm in diameter, with the entire system fitting within an area of 1 mm x 0.5 mm. Continuous Time Delta Sigma (CT∆ΣM) ADCs emerge as a promising solution given their power efficiency and reduced requirements on peripheral circuits. These ADCs boast advantages like built-in anti-alias filtering and simplified input buffer requirements. However, their susceptibility to clock jitter, especially in single-bit versions, presents challenges. This research introduces an original MATLAB and Simulink model for the CT∆ΣM. The model initially accounted for clock jitter employing a white noise spectrum. However, subsequent analysis unearthed a profound limitation: while FIR filters within the CT∆ΣM reduced periodic jitter’s impact, they were vulnerable to non-white noise spectrums. Although present in CT∆ΣM literature, this significant observation was previously uncharted for the signal bandwidth applications akin to this work. To address this, the research delves into creating a comprehensive Phase noise spectrum model using MATLAB. This model elucidates the profound limitations imposed on the ADC’s in-band noise by the clock source’s phase noise spectrum, a revelation that reshaped our understanding of the CT∆ΣM’s constraints. Originally, a detailed schematic design for the clock source was undertaken with the primary objective of optimising area and power consumption, relying on a Resistor Capacitor based clock source for the Frequency-Locked Loop (FLL). The prevalent belief was that the typical phase noise spectrum of clock sources would have a negligible influence on the CT∆ΣM ADC. However, post-chip measurement analysis dispelled this notion. This research discovered that the clock source’s phase noise spectrum profoundly affected the CT∆ΣM ADC’s performance, highlighting an overlooked yet critical interplay.Item Development of a wearable system for monitoring people with Parkinson’s at home(University College Cork, 2023) Sica, Marco; O'Flynn, Brendan; Tedesco, Salvatore; AbbVie; Enterprise IrelandParkinson's disease (PD) is a neurodegenerative disorder affecting the central nervous system. Besides impairing motor functions, PD is also characterized by a broad variety of non-motor symptoms, such as mood and cognitive disorders, hallucinations, and sleep disturbances. People with Parkinson’s (PwP) are evaluated using clinical assessments and self-administered diaries and, as a consequence, they receive the necessary pharmacological therapy to alleviate symptoms and enhance sleep quality. Tri-axial accelerometers and gyroscopes might be employed to objectively evaluate Parkinsonians’ condition and help clinicians in making decisions. PwP often have significant abnormalities in blood pressure (BP) due to comorbid age-related cardiovascular disease and orthostatic hypotension, which result in blurred vision, dizziness, syncope, and falls. Frequent BP monitoring may aid in the evaluation of such events and differentiate PD symptoms from those originated by hypotension. A number of commercially available devices designed specifically for PwP include accelerometers and gyroscopes for the estimation of main motor symptoms, gait parameters, and sleep quality; nevertheless, according to the authors' knowledge, neither commercially available systems nor published works include also photoplethysmograph (PPG) and electrocardiogram (ECG) sensors that can be used for Parkinsonians’ cardiovascular monitoring. In this work, the WESAA (Wearable Enabled Symptom Assessment Algorithm) system is introduced as a revolutionary tool for the remote monitoring of PD patients. It is comprised of two devices worn on the wrist and ankle, and its key purpose is to capture accelerations and angular velocities from these body parts, as well as PPG and ECG data. This information may be used off-line to predict common PD motor symptoms (such as tremor, bradykinesia, and dyskinesia), walking speed, sleep-wake cycles, and cuff-less BP measures. The system requirements, market overview, industrial design, hardware and firmware development, user experience, early results of the gathered inertial raw data, and validation of the PPG and ECG signals were looked at in detail in the present work. The created system fulfils all the defined user requirements, and the sensors used yielded results equivalent to gold standard technologies. This thesis also studied the PwP's viewpoints on the WESAA system which is crucial for usability and adherence, examining practical concerns such as size, design, and comfort, as well as emotional consequences, societal impact, and the significance of discretion. In addition, users discussed their data-sharing preferences and how wearable technology could enhance their lives (i.e., the necessity to give feedback, particularly on motor symptoms). The WESAA system thus presents a promising alternative for remote monitoring of PwP since it has the ability to assist physicians in decision-making in terms of medication and treatment, giving them potentially useful information about the motor symptoms and the overall health status of their patients. Future work involves the implementation of off-line solutions for the detection of PD motor symptoms, walking speed, sleep-wake cycles, and cuff-less BP; machine learning algorithms should be adopted and a broader data collection carried out.Item Low-cost integration technologies for next generation wearable devices(University College Cork, 2023) Federico, Andrea; O'Flynn, Brendan; Belcastro, Marco; Enterprise Ireland; DeRoyal Industries; Science Foundation IrelandIn recent years, the commercial and research interest in the development of textile based products incorporating embedded micro-electronic elements, such as sensors, microcontrollers batteries etc., also known as e-textiles, has grown considerably. This has resulted in significant progress in researching new methods of electronics integration and the utilisation of wearable systems in a variety of applications in different fields. However, despite the results obtained to date, the requirements associated with e-textile applications, such as being lightweight, small in size, and stretchable still present a significant engineering challenge and topic of interest to the research community. Moreover, due to their close contact with the human body, the design of e-textile devices must consider several aspects related to the user experience associated with such wearable systems. As a consequence, freedom of movement, non-intrusiveness and overall comfortability must be guaranteed to ensure uptake of the technology in a consumer product setting. Over the past decade, a variety of strategies for textile electronics integration have been investigated and developed by the research community. New strategies for the use of conductive materials have been developed to replace the use of traditional conductive wires or cables and thus improve system wearability and durability, since the presence of cables can restrict body movements and prevent the execution of specific physical tasks. Such novel materials are increasingly accessible to system designers in the form of conductive threads, fabrics and inks which open up new opportunities for wearable electronic systems. There are different methods of integrating rigid and flexible electronic components into/onto textiles for the development of wearable e-textile systems, including chemical, physical and mechanical strategies. In this work, we present a review of the state of the art in the research literature as well as in commercially available products regarding the main integration strategies available to system designers. Moreover, an evaluation of and performance’s analysis of novel conductive materials is presented, as well as an implementation of a low-cost integration technique for e-textiles and wearable sensing systems. As a proof of concept and validation activity, two system demonstrators are presented: a full-body suit which is able to capture the EMG signals coming from the lower body through conductive traces; and an inflatable cuff embedding standard electronic modules with integrated sensing actuation and communication developed as a medical device. Both the demonstrators integrate flexible substrates electronic components, sensors and power supplies. Future work will involve further testing on the reliability of the low-cost integration technique presented in Chapter 3 and, furthermore, the integration of flexible electronics and sensors onto the demonstrator smart compression system medical device, allowing for better monitoring of the wounds status and, therefore, better evaluation of the healing process associated with the use of compression bandages in a clinical setting.Item Development of a low-power, battery-less near field communication sensor transponder for wireless sensing applications(University College Cork, 2022-12-12) Gawade, Dinesh R.; Buckley, John; O'Flynn, Brendan; Horizon 2020; Science Foundation Ireland; European CommissionCultural heritage objects and artefacts are precious objects owned by museums and archives, which are generally old and fragile. Often, such objects are stored in climatically uncontrolled storage areas, particularly inside sealed archive boxes and storage crates. Such storage practices can lead to significant degradation of valuable artefacts. Implementing air conditioning and heating, ventilation, and air conditioning (HVAC) systems constitutes a highly technical conservation challenge that often cannot be financially justified, especially for small and medium-sized museums. Commercially available environmental sensors, such as hygrometers and wireless data loggers are known for monitoring microenvironments in museums. However, these devices are unsuitable for integration within museum storage boxes because these sensors are either too large or expensive. For example, the Testo series 160TH data logger can be used for monitoring temperature and humidity in museum environments but the cost is significant at approximately €245. Another critical disadvantage associated with monitoring the inside microenvironments of an archive box using a hygrometer is the necessity to open the box for the analysis. A key disadvantage of existing methods is the interference caused to the internal microclimate. This thesis presents the development of both short-range and long-range wireless sensor platforms that monitor the microclimatic environment inside museum artefact storage boxes. The short-range wireless communication platform focuses on developing a battery-less near-field communication (NFC) sensor transponder with a wireless communication range of several centimetres. On the other hand, the long-range communication platform development involves the selection and implementation of optimum wireless communication technology to yield a wireless communications range of 100 metres to several kilometres and which is scalable according to the large number of artefacts that may need to be monitored. In the first contribution, for the first time, a smart museum archive box that features fully integrated wirelessly powered temperature and humidity sensing capabilities is developed and demonstrated. The developed NFC sensor transponder has been optimized for low power operation using voltage and frequency scaling techniques with a measured peak DC power consumption of 597 μW while yielding a 5 cm wireless communication range. The achieved power consumption is 33.6 % lower in comparison with the current state-of-the-art in this area. In addition, the developed battery-less NFC sensor transponder can wirelessly measure temperature and relative humidity with a mean error of ± 0.37 ◦C and ± 2 %, respectively, over a maximum distance of 5 cm. In addition, a battery-less NFC humidity sensor prototype is developed and demonstrated using laser-induced graphene (LIG) electrodes and a graphene oxide (GO)-based humidity sensor. Furthermore, the feasibility of enhancing the wireless communication range of the NFC sensor transponder is explored. This is achieved by powering the transponder electronics using energy harvested from a vibrational energy harvester. A maximum wireless communication range of 11 cm is achieved in free space, which is 120 % beyond the state-of-the-art reported in the literature. Finally, the developed battery-less NFC sensor transponders were deployed in Cork Public Museum, Cork, Ireland and Fondazione Scienza e Tecnica (FST) in Florence, Italy to monitor artefacts in these museums. In addition, the transponder was also deployed in the world-famous Guggenheim museum in Venice, Italy, to monitor the interior temperature and humidity of Andy Warhol’s painting entitled flowers. In the second contribution, the optimum wireless communication technology for museum artefact monitoring applications in warehouses and exhibition cabinets was identified. For the identified technology (LoRaWAN), a testbed network was developed and deployed (7 sensor nodes) as proof of concept at Cork Public Museum, Cork, Ireland, to monitor the interior temperature and humidity of artefact display cases and storage cabinets. The wireless communication performance of LoRaWAN is shown to offer the optimal solution for wireless communication for this long-range application with a measured packet delivery ratio of 0.994 and an estimated battery lifetime of 10 years, considering a duty cycle of 1 data packet per day. The outcomes of this thesis contribute to the advancement of museum artefact monitoring, battery-less NFC sensing state-of-the-art for short-range storage analytics and a LoRaWAN solution for long-range analysis of warehouse cabinets and exhibitions.Item Monolithic, tunable, single frequency, narrow linewidth lasers using quantum well intermixing(University College Cork, 2022-06) Jia, Zhengkai; Peters, Frank H.; Hao, Guangbo; Science Foundation IrelandWith the development of Internet technology, the number of Internet users and Internet traffic has increased exponentially every year, and there is a large-scale demand for photonic components at the core of optical communication networks. Semiconductor lasers are the heart of photonic devices which are attractive for their low form factor, mass producibility and compatibility with photonic integrated circuits (PICs). Quantum well intermixing (QWI) is one of the important monolithic techniques used in the integration of PICs. QWI is a post-growth technique, which is used in the preparation of integrated devices and creates a modified energy band gap of a quantum well without any regrowth. QWI in Indium phosphide (InP) based AlGaInAs multiple quantum well active regions was demonstrated in this dissertation by applying QWI to monolithic tunable single frequency narrow linewidth lasers. This design reduces both the potential cost and power consumption of the devices. This work has been focused on creating small size coherent optical laser sources, making them attractive devices to satisfy the rising demand for photonic components. This work investigates the development of components that can be simply fabricated without requiring any epitaxial regrowth. A regrowth-free monolithic InP-based laser / photonic integrated circuit (PIC) was demonstrated with tunable single-frequency operation in the C + L bands and a sub 10 kHz linewidth. The laser PIC integrates a gain section with a 1×2 multimode interferometer (MMI), a linear curvature ring reflector on one side and a slotted mirror on the other. The MMI and ring reflector were made transparent to the gain wavelength using the impurity-free vacancy disordering (IFVD) quantum well intermixing technique to extend the cavity for narrow linewidth. The slotted mirror acts as higher order distributed Bragg reflector (DBR) to select the lasing mode. The laser was fabricated using the typical Fabry Perot (FP) laser process used in the Integrated Photonics Group, with a self-aligned technique for achieving two etch depths. The fabricated laser demonstrated single longitudinal mode tunability over a 39 nm range with a side mode suppression ratio (SMSR) of greater than 35 dB and a 3.79 kHz linewidth at room temperature with 87 mA current injection on the gain section and 115 mA on the slotted mirror section.