SACM - United Kingdom
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9667
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Item Restricted Corneal Expansion for Blindness Prevention(Imperial College London, 2020-09) Banaama, Saeed; Stevens, MollyCorneal shortage is a major issue, which limits the number of corneal transplant procedures performed worldwide. It is estimated that only one cornea is available per every seventy needed. Approximately 200,000 vision-saving CTs take place annually worldwide, but there are another 12 million people waiting for corneas. The majority of these patients are located in India and China. The number of people in need of corneas is expected to rise due to the aging population. Corniplex has developed a novel approach for addressing this shortage using stem cell and regenerative medicine technologies. There are currently no biosynthetic corneas on the market. The product is currently in the development stages and the preclinical trials are expected to be completed in 2024. The device is classified as a combination product under FDA guidelines and is anticipated to enter the market in 2030, following the successful completion of an international phase III clinical trials. Corniplex is targeting India as its initial market. We anticipate annual peak sales in 2040, with revenues reaching up to $7 million dollars annually. To achieve this objective, we attempted to optimise the printing conditions of Gelatin Methacryloyl (GelMA) , one of the most widely used materials in bio-applications due their biocompatibility and biodegradability profile. In the technical part of this thesis, the photo-rheology of GelMA is investigated to determine its suitability to be used as a bioink in Stereolithography based 3D printing. The impact of changing the degree of functionalisation (DOF, 42 vs. 93%), photoinitiator concentration (0.2-1% wt), and GelMA concentrations (50, 100, and 200 mg/mL) on growth rate and time to halfway point (thwp) is examined and compared semi-empirically using a Gompertz function. The results show a higher growth rate (0.007 vs. 0.01) and a decrease in thwp with higher photoinitiator concentration (394 vs. 240 s) – indicating a more rapid polymerisation. Higher GelMA concentrations showed a higher growth rate for lower concentrations (0.025 at 50 mg/mL vs. 0.01 for 100 and 200 mg/mL). On the other hand, the increase in GelMA concentration resulted in decrease to thwp (315 vs. 196 s, for 50 and 200 mg/mL, respectively). The greatest effect of the DOF was observed at 200 mg/mL with regards to thwp (210 vs. 280 s, the former being the sample with 93% DOF). The growth rate was slightly higher in the samples with higher DOF in the 100 mg/mL GelMA. However, this effect seems to subside with the 200 mg/mL GelMA, indicating the possibility that DOF is might be less relevant with higher GelMA concentrations.14 0Item Restricted Layered Extrusion of engineering Metal Alloys (LEMA) using Semi-Solid Thixotropic Feedstock(The University of Sheffield, 2023-08-31) Alharbi, Abdullah; Mumtaz, KamranAdditive manufacturing (AM) has gained significant attention in low- and medium-volume industries due to its ability to create custom products with complex shapes, design freedom, material savings, and short lead times. While most AM processes focus on thermoplastics, there is increasing interest in metal AM systems, including powder bed fusion processes. However, these methods often involve high acquisition and operating costs, limiting accessibility. To address this, this study focuses on developing and investigating the Layered Extrusion of Engineering Metal Alloys (LEMA) system as a cost-effective alternative metal AM approach. The LEMA system manipulates alloys in the semi-solid thixotropic state. Utilising semi-solid metal slurry in extrusion-based AM can result in metal components with substantially lower operating costs and reduced thermal stresses compared to laser-based method. Experimental work initially conducted (Phase I) using the LEMA system involved in-situ creation of semi-solid thixotropic metallic alloys, particularly focusing on the Zn-Sn binary system, but improvements were made to the LEMA system for the subsequent phase to enhance performance. In Phase II, thermodynamic simulations and thermal analysis have indicated that Zn-40Sn holds promise for semi-solid thixotropic applications. Cold extrusion and heat treatment processes were employed to produce thixotropic feedstock with proper microstructures before being additively manufactured. The 3D printed components were evaluated and the result suggested that the adapted method for semi-solid billets preparation was feasible technique which then helped in a successful printing metallic material. Additionally, printing experiments were conducted to study the effects of major process parameters on the quality of deposited single-layer. It was demonstrated that single layers could be printed under 1.5 mm diameter orifice, extrusion speed of 20 mm/min, substrate moving velocity of 200 mm/min, and extrusion temperature of ≈313 ℃. The optimized printing process parameters from these experiments were then utilized for multilayer printing. It was found that substrate temperature is a key factor for achieving good metallurgical layer bonding at the interface of the printed layers. The research results support LEMA's feasibility as an alternative for the metal additive manufacturing route and lays the groundwork for processing SSMs with higher melting points in the future.4 0Item Restricted Future Glass Factory: Precision Shaping of Glass using Amorphous Silica Nanocomposite Prepolymer and Replication Molding(Queen's University Belfast, 2024-05-15) Atwa, Yahya; Shakeel, Hamza; McNeill, DavidGlass, a versatile and indispensable material, plays a crucial role in industries such as electronics, optics, and chemical sensing due to its exceptional transparency, thermal stability, and recyclability. Despite the benefits of traditional glass fabrication methods like glass blowing, these approaches face significant challenges, including energy-intensive processes, susceptibility to defects, and limitations in creating complex geometries. To address these issues, this thesis introduces a novel fabrication method that combines printable amorphous silica nanocomposite suspensions with replication molding. This innovative technique offers enhanced design flexibility, reduced material waste, and cost-effective production, enabling the creation of intricate 2D and 3D geometries with improved structural and surface quality. The research explores this method’s applications in chemical sensing and resonant devices, highlighting its transformative potential for advanced glass manufacturing. The proposed method employs polydimethylsiloxane (PDMS) molds as templates. A glass prepolymer is dispensed into these molds, cured using ultraviolet light, and then subjected to thermal debinding and sintering processes. These steps transform the prepolymer into fully fused silica, achieving uniform thickness, minimized shrinkage, and smooth surfaces. To validate the method, extensive characterization techniques, including surface roughness measurements, thermal analysis, and computational modeling, were employed to ensure high-quality outcomes. Optimization strategies further enhanced device performance by addressing challenges such as bending during processing and improving sintering results. This thesis demonstrates the efficacy of this approach through key applications. For chemical sensing, a transparent 3D-printed fused silica gas chamber was integrated with a graphene-based sensor for detecting volatile organic compounds (VOCs). The chamber's transparency enabled ultraviolet-assisted regeneration of graphene’s adsorption properties, restoring sensitivity and ensuring long-term stability. Additionally, a micro dielectric barrier discharge photoionization detector (μDBD-PID) was developed using this technique. This detector employed a colorimetric readout mechanism to analyze changes in plasma luminescence during VOC detection, achieving high sensitivity and selectivity for both polar and non-polar compounds. These advancements highlight the method’s capacity to produce robust and high-performance chemical sensing devices. In the field of resonant devices, the fabrication process was used to create planar double paddle oscillators (DPOs) with varying thicknesses (0.5 mm, 0.8 mm, and 1 mm). These devices exhibited excellent resonance characteristics, with the 1 mm thick DPO achieving a quality factor (Q-factor) of 1,261 in the CL1 mode and 4,563 in ring-down measurements. Similarly, 3D hemispherical resonators (HSRs) were fabricated, with significant improvements in surface smoothness, reducing roughness to 103 nm in second-generation devices. Experimental and computational analyses identified resonance modes (N = 2, N = 3, N = 4), with the highest Q-factor of 482k observed in the N = 3 mode. These results highlight the method's ability to produce high-performance resonant structures essential for sensitive detection and precision applications. In conclusion, this thesis presents a transformative approach to glass fabrication that combines innovative techniques and meticulous optimization to overcome the limitations of traditional methods. By demonstrating its applicability in chemical sensing and resonant device manufacturing, the research underscores the potential of printable glass technologies to revolutionize precision manufacturing. The findings significantly contribute to advancing the state of the art in microfabrication, paving the way for innovative solutions across academia and industry. This work highlights the integration of sustainability, efficiency, and advanced functionality in modern glass-manufacturing processes.21 0Item Restricted Future Glass Factory: Precision Shaping of Glass using Amorphous Silica Nanocomposite Prepolymer and Replication Molding(Queen's University Belfast, 2024) Atwa, Yahya Adnan; Shakeel, Hamza; McNeill, DavidGlass, a versatile and indispensable material, plays a crucial role in industries such as electronics, optics, and chemical sensing due to its exceptional transparency, thermal stability, and recyclability. Despite the benefits of traditional glass fabrication methods like glass blowing, these approaches face significant challenges, including energy-intensive processes, susceptibility to defects, and limitations in creating complex geometries. To address these issues, this thesis introduces a novel fabrication method that combines printable amorphous silica nanocomposite suspensions with replication molding. This innovative technique offers enhanced design flexibility, reduced material waste, and cost-effective production, enabling the creation of intricate 2D and 3D geometries with improved structural and surface quality. The research explores this method’s applications in chemical sensing and resonant devices, highlighting its transformative potential for advanced glass manufacturing. The proposed method employs polydimethylsiloxane (PDMS) molds as templates. A glass prepolymer is dispensed into these molds, cured using ultraviolet light, and then subjected to thermal debinding and sintering processes. These steps transform the prepolymer into fully fused silica, achieving uniform thickness, minimized shrinkage, and smooth surfaces. To validate the method, extensive characterization techniques, including surface roughness measurements, thermal analysis, and computational modeling, were employed to ensure high-quality outcomes. Optimization strategies further enhanced device performance by addressing challenges such as bending during processing and improving sintering results. This thesis demonstrates the efficacy of this approach through key applications. For chemical sensing, a transparent 3D-printed fused silica gas chamber was integrated with a graphene-based sensor for detecting volatile organic compounds (VOCs). The chamber's transparency enabled ultraviolet-assisted regeneration of graphene’s adsorption properties, restoring sensitivity and ensuring long-term stability. Additionally, a micro dielectric barrier discharge photoionization detector (μDBD-PID) was developed using this technique. This detector employed a colorimetric readout mechanism to analyze changes in plasma luminescence during VOC detection, achieving high sensitivity and selectivity for both polar and non-polar compounds. These advancements highlight the method’s capacity to produce robust and high-performance chemical sensing devices. In the field of resonant devices, the fabrication process was used to create planar double paddle oscillators (DPOs) with varying thicknesses (0.5 mm, 0.8 mm, and 1 mm). These devices exhibited excellent resonance characteristics, with the 1 mm thick DPO achieving a quality factor (Q-factor) of 1,261 in the CL1 mode and 4,563 in ring-down measurements. Similarly, 3D hemispherical resonators (HSRs) were fabricated, with significant improvements in surface smoothness, reducing roughness to 103 nm in second-generation devices. Experimental and computational analyses identified resonance modes (N = 2, N = 3, N = 4), with the highest Q-factor of 482k observed in the N = 3 mode. These results highlight the method's ability to produce high-performance resonant structures essential for sensitive detection and precision applications. In conclusion, this thesis presents a transformative approach to glass fabrication that combines innovative techniques and meticulous optimization to overcome the limitations of traditional methods. By demonstrating its applicability in chemical sensing and resonant device manufacturing, the research underscores the potential of printable glass technologies to revolutionize precision manufacturing. The findings significantly contribute to advancing the state of the art in microfabrication, paving the way for innovative solutions across academia and industry. This work highlights the integration of sustainability, efficiency, and advanced functionality in modern glass-manufacturing processes.27 0Item Restricted Additive Manufacturing of Continuous Fibre Reinforced Polymer Composites Through Combination of Rapid Tow Shearing Deposition and Layer-by-Layer Curing(Cranfield University, 2024) Althomali, Abdulaziz; Skordos, Alex; Asareh, MehdiThis research aims to explore the advancement of an additive manufacturing technique for continuous fibre reinforced polymer (CFRP) composites by combining Rapid Tow Shearing (RTS) deposition with Layer-by-Layer (LbL) curing. This approach aims to address the challenges associated with conventional manufacturing of thermoset composites, such as extended curing cycles, temperature spikes, and defects arising from inconsistent curing. A Finite Element (FE) model was developed to simulate the thermal response of CFRP composites during the LbL-RTS process. Validation results demonstrated a strong correlation between the model predictions and experimental data, confirming the accuracy of the developed model. The integrated process envelope was investigated through a set of simulations. Findings from the study illustrate that the LbL-RTS process can effectively reduce temperature overshoot by up to 30°C compared to traditional monolithic curing methods, thereby helping maintain material integrity and minimise the risk of thermal degradation. In addition, a parametric analysis is conducted to uncover the impact of varying deposition speeds on temperature profiles. The study found that for every 0.5 mm/s increase in deposition speed, the temperature overshoot rises by 5°C. However, higher deposition speeds at 100% IR power reduce temperature spikes by 6°C. Future improvements include adding mechanical properties in FE to predict and understand mechanical behaviour. Developing a deposition head that combines RTS benefits with an embedded flash lamp for irradiating tapes during deposition. Mechanical tests such as peel ply or Interlaminar Shear Strength on LbL-RTS samples would assess the interfacial and structural integrity of the produced component.36 0Item Restricted Felodipine Solubility Enhancement via Polymeric-Lipid Extrusion 3D Printing, and Public Acceptance Toward 3D Printed Medicines(University of Nottingham, 2024) Ismail, Doaa; Roberts, ClivePoor aqueous solubility of many prospective low molecular weight drug compounds is a barrier to bioavailability and hence therapeutic effectiveness and commercial potential. Multiple formulation-based approaches have been studied to enhance effective solubility, one of which is the formation of the drug in a solid dispersion, whereby the drug is dispersed in a soluble matrix. 3D printing has capabilities to produce personalised medicines and is a manufacturing technique for pharmaceuticals well suited to the creation of solid dispersions. Multiple 3D printing technologies are available, with material extrusion approaches most often used in pharmaceutical research to date. With such advances in 3D printing, there is also the opportunity for studies of patient-perceptions of printed tablets in the context of tablet properties such as size, shape, and colour. As a new manufacturing technology, understanding patient acceptability of 3D printing of medicines is required to understand the public perception toward future market along with policy shaping. As part of this study a public study is carried out on the acceptance of 3D printed tablets. The aligned main aim of this study was to study the potential of polymeric-lipid formulations to enhance drug water solubility in extrusion 3D printed solid dosage forms, designed according to the most acceptable geometries of the public. Such formulations have rarely been studied in 3D printing of tablets. Specifically, I investigated the poorly water soluble drug felodipine and its inclusion in a polymeric-lipid formulation. An immediate-release formulation was developed and tested for printability and compatibility. The developed formulation exhibited enhanced solubility, excellent printability, and compatibility. Subsequently I describe the study of sustained-release formulations with altered ratios of drug and excipients. A significant difference was present between formulations with variable drug content. As most lipids undergo physicochemical changes over time, stability determination is considered. The samples were tested under various storage conditions. Several analytical techniques were used to verify any changes that occur during the stability analysis. Samples stored at room temperature and 0% RH showed rapid crystallisation of felodipine, whereas those stored at 37 ± 1°C and 75% RH maintained their amorphous and dispersed state. Augmentation of the drug release rate was observed in all aged samples compared to the freshly printed samples. Multiple complementary methods were used to study formulation behaviour and structure. Employment of social study results in the design of future medicines can enhance their effectiveness. Additionally, lipids with their versatility as drug carrier are ideal for extrusion 3D printing for the use in pharmaceutical manufacturing, particularly clinical trials.11 0Item Restricted Development of Robots and Algorithms for Cooperative Additive Manufacturing(University of Manchester, 2024-04-11) Alhijaily, Abdullah; Bartolo, Paulo; Cangelosi, AngeloAdditive manufacturing (AM) is dominated by single robots which present limitations in fabrication time and efficiency of the system. To address this problem, this research explores the concept of cooperative printing in which multiple printheads fabricate the same part concurrently. However, configurations for cooperative printing in the literature present several limitations such as reduced cooperative printing area and cross prevention in which no two printheads are allowed to cross each other's paths during printing. Thus, a novel configuration is proposed in this research. This configuration was realised on a custom gantry machine. As shown, the proposed configuration allows printing parts that are impossible to print or inefficiently printed by other cooperative printing configurations. Furthermore, several novel algorithms are formulated and implemented in the developed machine. Additionally, efficient algorithms were developed for path planning that allowed to reduce the computation time of slicing for cooperative printing from minutes to milliseconds. Also, the proposed system significantly increased the printing speed surpassing the maximum printing time reduction reported in the literature. Conversely, mobile robots are promising for AM due to their large workspace. However, current plastic AM by mobile robots produce parts with poor quality and rough surface finish. Thus, an accurate mobile robot specialised for mobile AM is developed for this research. The proposed mobile robot's accuracy and precision were assessed and was found to have a 0.37 mm average error surpassing the literature on mobile AM. Finally, it was shown that the developed mobile robot surpasses them both in terms of quality and accuracy. For gantry systems, offline path planning is reliable and efficient due to their high accuracy and predictability. However, it is unreliable for low accuracy and error-prone systems such as mobile robots. To overcome this, an online cooperative printing path planning designed for the developed mobile robot is proposed. Several novel real time algorithms were developed, including a novel online collision avoidance algorithm that guaranteed collision-free motions. This research stands as the first work to develop fully online path planning for cooperative printing.26 0Item Restricted Three Dimensional Printed Immunomodulatory Scaffolds with Controlled Drug Release for Bone Regeneration(Saudi Digital Library, 2023-10-24) Majrashi, Majed; Yang, Jing; Ghaemmaghami, AmirLarge bone defects pose significant challenges in orthopaedic surgery, necessitating the exploration of innovative repair technologies beyond traditional treatments like autografts, allografts, and synthetic substitutes, each fraught with specific challenges. Tissue engineering and regenerative medicine have emerged as promising fields, employing bioactive materials, growth factors, and cellular components to emulate natural bone properties and functions. Notably, additive manufacturing techniques contribute to these advancements by customising 3D-printed scaffolds enhancing patient-specific treatments. Recent studies underscore the significant influence of immune responses in bone regeneration, an area still in its infancy. Particularly, the modulation of immune reactions through specialised biomaterials and the strategic delivery of anti-inflammatory agents like dexamethasone present a novel approach to support bone healing processes, avoiding the systemic side effects of traditional drug administration. In this thesis, novel inks were developed to sustain the release of dexamethasone from a 3D-printed scaffold to modulate the immune response and osteogenesis. Excipients with surfactant properties, including the poloxamers F127, F68, L31, sorbitan monooleate Span80, and sucrose acetate isobutyrate (SAIB), were added to PCL to test their ability to sustain drug release. All these inks were fabricated into scaffolds by using direct ink writing 3D printing technique. The fabricated scaffolds were then characterised by SEM, DSC, FTIR, and ToF-SIMS. Macrophages and mesenchymal stem cells (MSCs) were cocultured to investigate the effects of the controlled release of dexamethasone on the modulation of macrophage polarisation and osteogenic differentiation of MSCs. Notably, blending PCL with 40% wt/wt (SAIB) has improved dexamethasone-cyclodextrin dispersal and facilitated a sustained 35-day release dominated by first-ordered and Higuchi models. In this modified environment, investigations into macrophage-mesenchymal stem cell (MSC) interactions revealed that controlled dexamethasone release significantly influenced macrophage behaviour and MSC osteogenic differentiation. M1 macrophages boosted early alkaline phosphatase production (ALP) at (7 days), while later stages (21 days) saw dexamethasone's predominance. Bone morphogenic protein-2 (BMP-2) was significantly increased at day 21; meanwhile, interleukin-6 (IL-6) decreased at the same time. Moreover, the released dexamethasone switched the phenotype of macrophages from M1 to M2 at day 21, evidenced by the increased level of mannose receptor and decreased expression of calprotectin receptor. These results offer new insight into macrophage-MSC cross-talk and demonstrate the potential of drug-release scaffolds to modulate inflammation and enhance bone regeneration.21 0Item Restricted THE INFLUENCE OF MICROSCOPIC FEATURES ON THE SELF-CLEANING ABILITY OF 3D PRINTED FABRIC-LIKE STRUCTURES(Saudi Digital Library, 2022-09-30) Atwah, Ayat Adnan; Muhammad, KhanSelf-cleaning surfaces are getting significant attention within multiple scientific and industrial fields. Especially for textile fabrics, it is observed that self-cleaning textile fabric surfaces are created by manipulating the surface features with the help of coatings and nanoparticles, which are considered costly and far more complicated. However, the exploration of the potential for self-cleaning by controlling the fabrication parameters of textile fabrics at the microscopic level has not been addressed. The purpose of this study was to establish the context of self-cleaning textile fabrics by controlling the fabrication parameters of the fabric at the microscopic level. The control of the fabrication parameters is not easy in conventional fabric manufacturing techniques. Due to this reason, most textile fabrics use surface coating methods for self-cleaning features. The current evolution in 3D printed technology provides an opportunity to control the fabrication parameters during fabric manufacturing and generate self-cleaning features at the woven structural level. This study focuses on the possibility of developing a 3D-printed self-cleaning textile fabric using different printing parameters. It also identifies the significance of the fabric’s microscopic features, such as porosity, surface roughness, and wettability, along with the aesthetic look after optimizing these features. Further, the influence of these features on mechanical strength at the fabric woven structure level was tested. The optimization of printing parameters was modelled to identify the optimum self-cleaning properties for the 3D-printed specimens and the validation model was accomplished under a set of experimental methods. The study includes the combination of three printing parameters: layer height (LH) (0.15, 0.13, 0.10 𝑚𝑚) and extruder width (EW) (0.5, 0.4, 0.3 𝑚𝑚), along with two different angular printing orientations (O) (45 ° and 90 °). The other parameters, such as nozzle temperature (℃), print speed (𝑚𝑚/𝑠), and infill density (%), remained constant for all the samples. Three different thermoplastic flexible filaments printing materials are used: thermoplastic polyurethane (TPU 98A), thermoplastic elastomers (TPE felaflex), and thermoplastic co-polyester (TPC ii flex45). The 162 prepared samples are tested based on an experimental scheme to evaluate the self-cleaning ability. The microscopic features (porosity, roughness, and wettability) which are mainly responsible for this ability, are measured and recorded to evaluate and compare the best values for self-cleaning between the three chosen materials. The data are analysed to define the optimal self-cleaning number. Lastly, the experimental outputs are used in analytical calculations to find the relationship between changes in printing parameters and microscopic features. The study revealed that the printing parameters significantly affect the self-cleaning properties when optimizing the selection of the process parameter combination of layer height, extruder width, and printing orientation. The study successfully created a linear regression model to demonstrate the relationship between 3D printing parameters (layer height, extruder width, and orientation) and the self-cleaning microscopic features of the 3D-printed polymeric textile fabrics. It also identified that the (TPE) has a better self-cleaning ability than the other two materials.23 0Item Restricted Use of Advanced Technologies for the Improvement of Prosthetics Limbs.(Saudi Digital Library, 2023-08-17) Alenezy, Malik; Jayakody, Gayan; Smith, StephenThe act of amputation can have significant psychological consequences, including emotional anguish, depressive symptoms, anxiety, challenges with body perception, and diminished well- being. Understanding these psychological ramifications is essential for providing effective interventions and care for individuals with amputations. This research project aims to explore contemporary technological advancements and foreseeable obstacles in the prosthetics industry to improve the lives of amputees. The literature review reveals that the introduction of new materials and technology can enhance the quality of prosthetics, making them more lightweight, durable, and comfortable. Previous studies have utilised techniques like finite element analysis and virtual reality to understand the impact of prosthetic design on rehabilitation success and costs. The research methodology follows an "onion ring" structure to ensure comprehensive exploration of the topic. However, limitations, such as sample size and self-reporting reliability, are acknowledged. The data analysis includes both quantitative and qualitative data, with findings suggesting a need for new technologies in prosthetics and the importance of addressing discomfort and pain related to prosthetic sockets. The business model canvas for ProstheticsGuardian delineates the essential elements such key partners, activities, resources, value proposition, client categories, channels, customer connections, income streams, and cost structure. The present study serves to enhance comprehension of the psychological ramifications associated with amputation and provides valuable insights into the potential utilisation of sophisticated technologies to enhance prosthetic devices. The implementation of the recommendations derived from this research has the potential to improve the well-being and overall quality of life for those who have experienced limb loss in future studies and interventions.25 0