Browsing by Author "Kiani, Amirkianoosh"

Now showing 1 - 7 of 7
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    3D transient modeling of thin-film coated surfaces to predict the temperature and ablated areas during laser processing
    (University of New Brunswick, 2017) Naghshine, Babak, Baradaran; Kiani, Amirkianoosh
    Increasing the biocompatibility of biomaterials is a hot topic in biomedical engineering. Introducing new surface modification methods, that can just slightly enhance the biocompatibility can directly improve the quality of lives of thousands or millions of people all around the globe. The main goal of this thesis is to study laser processed thin film multilayer structures which can be potentially used for biomedical applications. In this thesis, the laser treatment process is numerically modeled to predict the temperature field and surface profile for each set of laser parameters including the average power, repetition rate and scanning speed. The model is successfully verified with experimental measurements. The same model was modified for laser processing of thin film coated metals. The results show that applying a thin film on the surface can completely change the temperature field and make the heat affected zone smaller or larger. A new surface modification method is introduced by combining laser processing and electrospinning technique. In this method, the surface is processed by laser beam and then it is coated with an electrospun thin layer. This method has potential applications in bone implant fabrication. The implant can benefit from excellent biocompatibility of the electrospun layer in short-term, before the fibers are degraded, as well as long-term biocompatibility of the laser treated surface. In vitro tests showed that, this method can improve the biocompatibility, especially when the laser processed surface is coated with nanoscale fibers. Furthermore, it is shown that, by applying the electrospun layer on the surface, the thermal conductivity of the surface is closer to human body’s conductivity. It makes it an attractive method for modification of dental implants, where the cells can be damaged while drinking a hot beverage. Additionally, antibacterial agents (e.g. silver and ampicillin) were added to the fibers as an antibacterial agent, to prevent implant infection.
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    Bioactivity enhancement of titanium by laser micro/nano surface texturing
    (University of New Brunswick, 2016) Radmanesh, Mitra; Kiani, Amirkianoosh
    The main objective of this thesis is to introduce laser treatment for enhancing the surface bioactivity of titanium for bone and tissue implant fabrication. Improvement to the implant performance could immensely benefit the human patient. Bioactivity enhancement of materials is currently an essential challenge in implant engineering. Micro/nano laser surface texturing of materials offers a simple, accurate method to increase the biocompatibility of materials in one single step. In this thesis, the effects of laser power, scanning parameters, and frequency on surface structure and topographic properties are studied. Through bioactivity assessment of treated titanium substrates, it was found that an increase in power and frequency increases the bioactivity of titanium, while a decrease in scanning speed of the laser could lead to an increase in the cell adhesion ability of titanium. Furthermore, cell adhesion proved to be strongest in areas with higher surface irregularities and titanium oxide concentrations.
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    Biocompatibility enhancement of crystalline silicon induced by nanosecond laser pulses for biomedical device fabrication
    (University of New Brunswick, 2017) Colpitts, Candace; Kiani, Amirkianoosh
    This thesis study aims to introduce nanosecond laser processing for the enhancement of biocompatibility of pure silicon for biomedical technologies. These results have the potential to contribute to the design of manufacturing processes of innovative biomedical devices and improve the quality of life. This research investigates the trends of various laser parameters including three scanning parameters (line spacing, overlap number, and scanning speed), pulse frequency, and laser power. Biocompatible in vitro assessment was conducted through the use of Simulated Body Fluid (SBF) and cell culturing with NIH 3T3 fibroblasts. The samples with smaller line spacing and higher overlap numbers showed more generation of SiO[subscript 2] nanofibres, which were shown to be biocompatible under SBF assessment. Scanning speed samples also showed an increase in biocompatibility at lower scanning speeds. Biocompatibility increased with frequency due to the hybrid amorphous SiO[subscript 2] being more prominent on high frequency samples and providing a favourable site for fibroblast cell proliferation. Fibroblasts also showed preference to higher powers. However, the heat affected zone immediately outside the ablated areas showed a mismatch of crystal orientations causing residual stress. These stress zones were avoided by cells, which lead to promising results for the potential in cell programming and manipulation.
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    Mouse embryonic fibroblasts accumulate differentially on titanium surfaces treated with nanosecond laser pulses
    (AVS: Science & Technology of Materials, Interfaces, and Processing, 2016) Radmanesh, Mitra; Ektasabi, Amin M.; Wyatt, Rachael A.; Crawford, Bryan D.; Kiani, Amirkianoosh
    Biomaterial engineering, specifically in bone implant and osseointegration, is currently facing a critical challenge regarding the response of cells to foreign objects and general biocompatibility of the materials used in the production of these implants. Using the developing technology of the laser surface treatment, this study investigates the effects of the laser repetition rate (frequency) on cell distribution across the surface of the titanium substrates. The main objective of this research is building a fundamental understanding of how cells interact with treated titanium and how different treatments affect cell accumulation. Cells respond differently to surfaces treated with different frequency lasers. The results of this research identify the influence of frequency on surface topography properties and oxidation of titanium, and their subsequent effects on the pattern of cell accumulation on its surface. Despite increased oxidation in laser-treated regions, the authors observe that fibroblast cells prefer untreated titanium to laser-treated regions, except the regions treated with 25 kHz pulses, which become preferentially colonized after 72 h.
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    Synthesis of onion-like carbon using 3-phase plasma reactor
    (University of New Brunswick, 2017) Zanjani, Arash, Davari; Chibante, L. Felipe; Kiani, Amirkianoosh
    Since the discovery of fullerenes in 1985, synthesizing nano-materials such as fullerene, onion like carbon (OLC), nanotube etc. has been widely researched. One of the most used techniques in synthesizing nanocarbons is the high temperature plasma method. The plasma method, in this case a 3-phase arc plasma, provides efficiency, low environmental impact, scalability, and greater purity. While the 3-phase plasma method has been studied in fullerene and nanotube production, utilizing the 3-phase plasma in the synthesis of OLC has yet to be investigated. The OLCs can be defined as giant molecules synthesized from carbon into the form of multilayered graphite. The OLC can be considered a hybrid nano-carbon with a structure between that of fullerene and graphene. The traditional methods of OLC production are batch based, expensive, and non-uniform, thereby limiting market use. This research studies 3-phase plasma synthesis of OLC. A 3-phase plasma reactor was modelled, designed, constructed, and operated at conditions required for OLC formation. A previously developed quasi-2D model using convection-diffusion in finite volume was utilized to monitor the key parameters: gas flow rate, residence time, and power. After heat treating an amorphous carbon feedstock by the plasma, the products were characterized by 3 different characterization methods: thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), and Raman spectroscopy. The results were then compared to the data gathered from the original feedstock and a reference OLC to determine conversion ratios. In addition, the energy efficiency of the plasma method was compared to conventional furnace annealing.
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    Synthesis of silica nanofibers embedded with gold nanoparticles by laser pulses and sputtering techniques
    (University of New Brunswick, 2017) Hamza, Sarah; Kiani, Amirkianoosh
    Many biomedical sensing applications require high electrical sensitivity as well as a method to control and implement them into biological applications. This requires a material to have both conductive and biocompatible properties. The lack of functional stability for implanted sensors has caused their restriction to short-term usage. Increasing the biocompatibility of these sensing devices generally causes a reduction in the overall conductivity due to the oxidation of the substrate. Silicon is becoming a more feasible and available option for use in these applications due to its semiconductor properties and availability. Previous work has proven the biocompatibility of porous Silicon through in-vitro testing with both SBF and NIH 3T3 culturing. A method to fabricate fibrous Silicon structures as well as control the conductivity of the latter through laser processing techniques and two coating methods are outlined in this thesis. The first involved Gold embedding through sputtering techniques, while the other utilized pre-coated Silicon achieved through PVD. An Nd:YAG pulsed nanosecond laser was employed to process the single crystalline Silicon wafers at a variety of line spacings, overlaps, and average powers. Controlling the scanning parameters were seen to induce the formation of nanofibrous structures. The conductivity of the samples were found to be dependent on both quantum effects and the overall Gold concentration on the surface. A biocompatibility assessment has shown traces of the elements necessary for the formation of hydroxyapatite. Overall, the method outlined in this research offers an economical and effective way to process Silicon into porous and fibrous structures while enhancing the conductivity and biocompatibility for the advancement of potential biomedical sensing and conductive tissue engineering applications.
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    Tethered water power electrical generator
    (University of New Brunswick, 2017) O'Rourke, Scott; McAllen, Nathan; Gant, Curtis; Kiani, Amirkianoosh
    This report conveys the design and experimental results of the completed tethered water powered electrical generator. Included here is an overview of background about different styles of waterwheels that were used to make preliminary decisions. Also here are finalized design specifications of the wheel itself including a 9 inch (228.6mm) diameter with an equal width. As the design was modified, the budget was changed to accommodate the additions, with a final cost coming in at $855, which includes the final prototype designed to fit and be tested in the UNB flume, as well as two extra sets of blades to be tested for comparison against the new design. Multiple analytical models have been considered, while each model is slightly different they all predict an output in the vicinity of one watt for the size of the prototype, with a water speed of 1 m/s. These calculations can also be used to figure out what size of wheel would be necessary to produce power for a larger electrical load. The testing results and observation are included as well. As the generator efficiency was unknown they are not identical to the theoretical but follow similar, obvious patterns. For example the power is linearly increased as the submerged area is increased. It was also noticed that the designed blades aided in reducing splashing. A few aspects to be considered for a larger model are also discussed including safety aspects as well as operating parameters. Although these sections are not relevant to the prototype constructed they are important factors to be considered for a larger scale generator, as is the ultimate goal of this project.