Nanomechanical resonators (NR) are cantilevers or doubly clamped nanowires (NW) which vibrate at their resonance frequency. These nanowires with picogram-level mass and frequencies of the order of MHz can resolve added mass in the attogram (10-18 g) range, enabling detection of a few molecules of cancer biomarkers based on the shift in resonance frequency. Such biomarker detection can help in the early stage detection of cancer and also aid in monitoring the treatment procedure in a more advanced stage. Optical transduction is one of the methods to measure the resonance frequency of the cantilever. However, there is a dependence of measured resonance frequency on the polarization of light and the laser power coupled as thermal energy into the cantilever during the measurement. This thesis presents a numerical model of the nanocantilever and shows the variation in resonance frequency and amplitude due to varied amounts of energy absorption by the NW from the laser during resonance measurements. This thesis answers questions on the effects of laser heating by calculating the temperature distribution in the NW, which changes the Young’s modulus and stiffness, causing a resonance downshift. It also shows the variation of resonance amplitude, affecting signal strength in measurements, by considering the effects of structural damping. In this work, a numerical model of the nanowire was analyzed to determine the temperature rise of the NW due to laser heating. The maximum temperature was calculated to be about 500 K with 1 mW of laser power absorbed in Silicon NWs and it is shown that the nanowire tip would reach its melting point for about 2.6 mW of laser power absorbed by it. The resonance shift due to attained temperature of the NW was calculated. The frequency is predicted to decrease by 24 kHz for a 11.6 MHz resonator, when 2mW of laser power is absorbed. However, the frequency shift is mode-dependent and is larger for higher modes. The variation in vibration amplitude around the resonance peaks is calculated based on the effects of structural damping. This can be used to decide on the suspension height of the NW above the substrate, before fabrication. This calculation also provides a method to study the variation in material damping due to temperature. Finally, a semi-analytical method for calculating the frequency of a cantilever beam with varying Young’s modulus is derived to examine the validity of the results calculated above. An effective Young’s modulus value for the laser heated NW is given, which serves as a correction factor for the resonance shift. The derivation is then extended to calculate the resonance shift with an addition of a mass to the beam of varying Young’s modulus. / Graduate / 2019-12-13

Main objective of this diploma thesis is to finish a construction of the Bulge test apparatus for measurement of thin films, perform first tests on commercially available Si3N4 membranes and bilayer membrane with aluminium. First part of the thesis is focused mainly on literature review of current knowledge regarding this topic and other methods of thin films testing. Experimental part deals with construction of apparatus, methodology of data evaluation and results of the measurement. The thin films of interest are fabricated as amorphous silicon nitride or bilayer of mentioned nitride and either aluminium, titanium or Ta-B-C layer. The apparatus has been built in house in collaboration with Institute of Scientific Instruments of CAS. Both reliability and repeatability of this method has been tested on over 160 measurements of commercially available membrane. The results of measurements are compared with literature and nanoindentation test. More detailed data analysis is currently under development with colleagues at Institute of Physics of Materials. It has been proven beyond doubt that Bulge test method and constructed apparatus are suitable for the measurement of several mechanical properties of thin films.

This diploma thesis deals with the determination of the Young’s modulus of coatings using the impulse excitation technique (IET). The theoretical part of the thesis describes Cold and Thermal Spray technology, theoretical foundations of the impulse excitation technique and models of composite materials. The experimental part of the thesis deals with the determination of the tensile modulus of copper coating created by Cold Spray technology. The impulse excitation technique has been used to measure fifteen samples with coating thickness ranging approximately from 0,4 to 2 mm. Results from this measurement were evaluated using five composite models to establish the Young’s modulus of the applied coating. The best results were achieved by using the composite model based on rule of mixtures (ROM).

Je utilise le AFM et le HS-AFM pour étudier les caractéristiques mécaniques du cellule du cristallin et aussi des protéines de membrane de la cellule, AQP0 et Connexon. L’énergie d'interaction de la AQP0 est -2.7 kBT, très nécessaire pour former les microdomaines de jonctions (junctional microdomain). Aussi c' est la première fois qu il est possible de voir des protéines individuel et son mouvement en cellules vivants. La formation de microdomaines est important pour la transparence du cristallin, et le AQP1 ne le peux faire. / I used the AFM and HS-AFM for characterise the eye lens and the eye lens membrane protein, AQP0 and connexon.A QP0-AQP0 interaction energy is -2.7kBT, it is important for the formation of junctional microdomains, which keep the distance between the cells lens and lens transparency. this is the first report which is present time the visualization of unlabelled membrane proteins on living cells under physiological conditions. AQP1 can not maintain the lens transparency because it does not form junctional microdomains.

Atmospheric plasma sprayed (APS) thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application such as power generation, marine and aero engines. TBC is a duplex material system consisting of an insulating ceramic topcoat layer and an intermetallic bondcoat layer. TBC microstructures are highly heterogeneous, consisting of defects such as pores and cracks of different sizes which determine the coating's final thermal and mechanical properties, and the service lives of the coatings. Failure in APS TBCs is mainly associated with the thermo-mechanical stresses developing due to the thermally grown oxide (TGO) layer growth at the topcoat-bondcoat interface and thermal expansion mismatch during thermal cycling. The interface roughness has been shown to play a major role in the development of these induced stresses and lifetime of TBCs.The objective of this thesis work was two-fold for one purpose: to design an optimised TBC to be used for next generation gas turbines. The first objective was to investigate the relationships between coating microstructure and thermal-mechanical properties of topcoats, and to utilise these relationships to design an optimised morphology of the topcoat microstructure. The second objective was to investigate the relationships between topcoat-bondcoat interface roughness, TGO growth and lifetime of TBCs, and to utilise these relationships to design an optimal interface. Simulation technique was used to achieve these objectives. Important microstructural parameters influencing the performance of topcoats were identified and coatings with the feasible identified microstructural parameters were designed, modelled and experimentally verified. It was shown that large globular pores with connected cracks inherited within the topcoat microstructure significantly enhanced TBC performance. Real topcoat-bondcoat interface topographies were used to calculate the induced stresses and a diffusion based TGO growth model was developed to assess the lifetime. The modelling results were compared with existing theories published in previous works and experiments. It was shown that the modelling approach developed in this work could be used as a powerful tool to design new coatings and interfaces as well as to achieve high performance optimised morphologies.

This thesis is inspired by a persistent limitation in the use of composite biomaterials for orthopaedic applications, namely the agglomeration of reinforcing particles in these composites, which has resulted in poor mechanical properties. The use of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and hydroxyapatite (HA) nanoparticles to produce biodegradable nanocomposites is investigated. More specifically, the thesis investigates different methods of composite processing, and interfacial modifying agents and the effect that these have on the nano- and micro- scale structure of composites and their mechanical properties. PHBV and HA were chosen because PHBV is a biodegradable/biocompatible polymer and it has a relatively high stiffness when compared to other biodegradable polymers frequently used in orthopaedic applications. HA is chemically similar to ceramic phase found in bones and hard tissues and the inclusion of HA into biomedical materials has been shown to enhance the rate of osteoconduction. HA/PHBV composites were produced using different dispersing agents including poly(acrylic acid) (PAA), a model dispersing agent, polyethyleneimine (PEI) which allowed for the development of a single solvent system for composite preparation, and heparin (Hep), a macromolecule which is produced in vivo. Additionally, HA/PAA/PHBV composites were prepared from both sonicated and non-sonicated HA/PAA suspensions up to approximately 17% by weight (wt %) of HA content. Attempts to prepare composites with higher HA loadings led to inhomogeneous composite mixtures, which were caused by the dual solvent system used for the composite preparation. The HA/PEI/PHBV and HA/Hep/PHBV composites were produced up to approximately 75 wt % of HA content. It was found that the HA/PEI/PHBV and HA/Hep/PHBV composites could be prepared at higher loadings than HA/PAA/PHBV composites due to the single solvent system used for the preparation of the HA/PEI/PHBV composites and the better dispersion of HA/Hep particles in precursor suspensions. Finally, selected HA/PEI/PHBV composites were further processed using a twin screw extruder. All of the composites were characterised in terms of their dispersion levels as well as their compressive mechanical properties. In addition, HA/PEI/PHBV composite reinforced with 20 wt % of HA content was also tested for its mechanical properties using three different test types; compression, three-point bending, and tensile tests. Finally, the HA/PAA/PHBV, HA/PEI/PHBV, and HA/Hep/PHBV composites were tested their compressive mechanical properties in wet state. It was found that the sonicated HA/PAA suspensions in general had better colloidal stability than non-sonicated ones and that this yielded composites with superior compressive moduli than those prepared from non-sonicated suspensions. In addition, the better dispersion of the particles in the composites prepared from the sonicated suspensions, as confirmed by transmission electron microscopic (TEM) images, led to higher percentage crystallinities when compared to the composites prepared from non-sonicated suspensions. It is likely that the greater number of individual HA particles and smaller HA agglomerates observed in the composites prepared from sonication treatment are acting as nuclei for crystal growth more effectively than large HA agglomerates. The largest modulus and yield strength that could be achieved with this system were approximately 1.45 GPa and 80 MPa, respectively. Composites of HA/PEI/PHBV and HA/Hep/PHBV with approximately 55 wt % of HA content were found to exhibit the largest compressive moduli of approximately 2.5 and 2.8 GPa, respectively. Moreover, the yield strengths for the same materials were found to be approximately 123 and 120 MPa, respectively. This was found to correlate with the better levels of dispersion within the nanocomposites that could be achieved using these stabilisers. The extruded samples were found to have an even greater degree of particle dispersion when compared to the unextruded ones. This improved degree of particle dispersion of the extruded samples resulted in higher moduli in comparison to unextruded samples. The largest compressive modulus and yield strength of the extruded samples were found to be approximately 3.2 GPa and 125 MPa, respectively. The compressive moduli of the composites produced in this thesis are significantly greater than that of cancellous bone (0.4 GPa), but significantly lower than that of cortical bone (12.8–17.7 GPa). However, maximum yield strengths of the HA/PEI/PHBV and HA/Hep/PHBV composites match to cortical bone (120–180 MPa), which is a noteworthy finding in this thesis. The wet mechanical results of all composites as well as pure PHBV polymer showed a reduction in both moduli and yield strengths when compared to dry state. In addition, after 2 weeks in wet state both moduli and yield strengths of the composites and pure polymer converged to approximately the same values. Finally, the HA/PEI/PHBV composite samples tested by tensile testing showed the highest Young’s modulus and those tested by compression testing possessed the lowest Young’s modulus. This resulted from the difference in periods of time for heating exposure and void contents of the tested samples, which were prepared by different methods. However, toughness values obtained from the samples tested using three-point bending and tensile tests, was not significantly different.

This thesis is inspired by a persistent limitation in the use of composite biomaterials for orthopaedic applications, namely the agglomeration of reinforcing particles in these composites, which has resulted in poor mechanical properties. The use of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and hydroxyapatite (HA) nanoparticles to produce biodegradable nanocomposites is investigated. More specifically, the thesis investigates different methods of composite processing, and interfacial modifying agents and the effect that these have on the nano- and micro- scale structure of composites and their mechanical properties. PHBV and HA were chosen because PHBV is a biodegradable/biocompatible polymer and it has a relatively high stiffness when compared to other biodegradable polymers frequently used in orthopaedic applications. HA is chemically similar to ceramic phase found in bones and hard tissues and the inclusion of HA into biomedical materials has been shown to enhance the rate of osteoconduction. HA/PHBV composites were produced using different dispersing agents including poly(acrylic acid) (PAA), a model dispersing agent, polyethyleneimine (PEI) which allowed for the development of a single solvent system for composite preparation, and heparin (Hep), a macromolecule which is produced in vivo. Additionally, HA/PAA/PHBV composites were prepared from both sonicated and non-sonicated HA/PAA suspensions up to approximately 17% by weight (wt %) of HA content. Attempts to prepare composites with higher HA loadings led to inhomogeneous composite mixtures, which were caused by the dual solvent system used for the composite preparation. The HA/PEI/PHBV and HA/Hep/PHBV composites were produced up to approximately 75 wt % of HA content. It was found that the HA/PEI/PHBV and HA/Hep/PHBV composites could be prepared at higher loadings than HA/PAA/PHBV composites due to the single solvent system used for the preparation of the HA/PEI/PHBV composites and the better dispersion of HA/Hep particles in precursor suspensions. Finally, selected HA/PEI/PHBV composites were further processed using a twin screw extruder. All of the composites were characterised in terms of their dispersion levels as well as their compressive mechanical properties. In addition, HA/PEI/PHBV composite reinforced with 20 wt % of HA content was also tested for its mechanical properties using three different test types; compression, three-point bending, and tensile tests. Finally, the HA/PAA/PHBV, HA/PEI/PHBV, and HA/Hep/PHBV composites were tested their compressive mechanical properties in wet state. It was found that the sonicated HA/PAA suspensions in general had better colloidal stability than non-sonicated ones and that this yielded composites with superior compressive moduli than those prepared from non-sonicated suspensions. In addition, the better dispersion of the particles in the composites prepared from the sonicated suspensions, as confirmed by transmission electron microscopic (TEM) images, led to higher percentage crystallinities when compared to the composites prepared from non-sonicated suspensions. It is likely that the greater number of individual HA particles and smaller HA agglomerates observed in the composites prepared from sonication treatment are acting as nuclei for crystal growth more effectively than large HA agglomerates. The largest modulus and yield strength that could be achieved with this system were approximately 1.45 GPa and 80 MPa, respectively. Composites of HA/PEI/PHBV and HA/Hep/PHBV with approximately 55 wt % of HA content were found to exhibit the largest compressive moduli of approximately 2.5 and 2.8 GPa, respectively. Moreover, the yield strengths for the same materials were found to be approximately 123 and 120 MPa, respectively. This was found to correlate with the better levels of dispersion within the nanocomposites that could be achieved using these stabilisers. The extruded samples were found to have an even greater degree of particle dispersion when compared to the unextruded ones. This improved degree of particle dispersion of the extruded samples resulted in higher moduli in comparison to unextruded samples. The largest compressive modulus and yield strength of the extruded samples were found to be approximately 3.2 GPa and 125 MPa, respectively. The compressive moduli of the composites produced in this thesis are significantly greater than that of cancellous bone (0.4 GPa), but significantly lower than that of cortical bone (12.8–17.7 GPa). However, maximum yield strengths of the HA/PEI/PHBV and HA/Hep/PHBV composites match to cortical bone (120–180 MPa), which is a noteworthy finding in this thesis. The wet mechanical results of all composites as well as pure PHBV polymer showed a reduction in both moduli and yield strengths when compared to dry state. In addition, after 2 weeks in wet state both moduli and yield strengths of the composites and pure polymer converged to approximately the same values. Finally, the HA/PEI/PHBV composite samples tested by tensile testing showed the highest Young’s modulus and those tested by compression testing possessed the lowest Young’s modulus. This resulted from the difference in periods of time for heating exposure and void contents of the tested samples, which were prepared by different methods. However, toughness values obtained from the samples tested using three-point bending and tensile tests, was not significantly different.

This thesis is inspired by a persistent limitation in the use of composite biomaterials for orthopaedic applications, namely the agglomeration of reinforcing particles in these composites, which has resulted in poor mechanical properties. The use of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and hydroxyapatite (HA) nanoparticles to produce biodegradable nanocomposites is investigated. More specifically, the thesis investigates different methods of composite processing, and interfacial modifying agents and the effect that these have on the nano- and micro- scale structure of composites and their mechanical properties. PHBV and HA were chosen because PHBV is a biodegradable/biocompatible polymer and it has a relatively high stiffness when compared to other biodegradable polymers frequently used in orthopaedic applications. HA is chemically similar to ceramic phase found in bones and hard tissues and the inclusion of HA into biomedical materials has been shown to enhance the rate of osteoconduction. HA/PHBV composites were produced using different dispersing agents including poly(acrylic acid) (PAA), a model dispersing agent, polyethyleneimine (PEI) which allowed for the development of a single solvent system for composite preparation, and heparin (Hep), a macromolecule which is produced in vivo. Additionally, HA/PAA/PHBV composites were prepared from both sonicated and non-sonicated HA/PAA suspensions up to approximately 17% by weight (wt %) of HA content. Attempts to prepare composites with higher HA loadings led to inhomogeneous composite mixtures, which were caused by the dual solvent system used for the composite preparation. The HA/PEI/PHBV and HA/Hep/PHBV composites were produced up to approximately 75 wt % of HA content. It was found that the HA/PEI/PHBV and HA/Hep/PHBV composites could be prepared at higher loadings than HA/PAA/PHBV composites due to the single solvent system used for the preparation of the HA/PEI/PHBV composites and the better dispersion of HA/Hep particles in precursor suspensions. Finally, selected HA/PEI/PHBV composites were further processed using a twin screw extruder. All of the composites were characterised in terms of their dispersion levels as well as their compressive mechanical properties. In addition, HA/PEI/PHBV composite reinforced with 20 wt % of HA content was also tested for its mechanical properties using three different test types; compression, three-point bending, and tensile tests. Finally, the HA/PAA/PHBV, HA/PEI/PHBV, and HA/Hep/PHBV composites were tested their compressive mechanical properties in wet state. It was found that the sonicated HA/PAA suspensions in general had better colloidal stability than non-sonicated ones and that this yielded composites with superior compressive moduli than those prepared from non-sonicated suspensions. In addition, the better dispersion of the particles in the composites prepared from the sonicated suspensions, as confirmed by transmission electron microscopic (TEM) images, led to higher percentage crystallinities when compared to the composites prepared from non-sonicated suspensions. It is likely that the greater number of individual HA particles and smaller HA agglomerates observed in the composites prepared from sonication treatment are acting as nuclei for crystal growth more effectively than large HA agglomerates. The largest modulus and yield strength that could be achieved with this system were approximately 1.45 GPa and 80 MPa, respectively. Composites of HA/PEI/PHBV and HA/Hep/PHBV with approximately 55 wt % of HA content were found to exhibit the largest compressive moduli of approximately 2.5 and 2.8 GPa, respectively. Moreover, the yield strengths for the same materials were found to be approximately 123 and 120 MPa, respectively. This was found to correlate with the better levels of dispersion within the nanocomposites that could be achieved using these stabilisers. The extruded samples were found to have an even greater degree of particle dispersion when compared to the unextruded ones. This improved degree of particle dispersion of the extruded samples resulted in higher moduli in comparison to unextruded samples. The largest compressive modulus and yield strength of the extruded samples were found to be approximately 3.2 GPa and 125 MPa, respectively. The compressive moduli of the composites produced in this thesis are significantly greater than that of cancellous bone (0.4 GPa), but significantly lower than that of cortical bone (12.8–17.7 GPa). However, maximum yield strengths of the HA/PEI/PHBV and HA/Hep/PHBV composites match to cortical bone (120–180 MPa), which is a noteworthy finding in this thesis. The wet mechanical results of all composites as well as pure PHBV polymer showed a reduction in both moduli and yield strengths when compared to dry state. In addition, after 2 weeks in wet state both moduli and yield strengths of the composites and pure polymer converged to approximately the same values. Finally, the HA/PEI/PHBV composite samples tested by tensile testing showed the highest Young’s modulus and those tested by compression testing possessed the lowest Young’s modulus. This resulted from the difference in periods of time for heating exposure and void contents of the tested samples, which were prepared by different methods. However, toughness values obtained from the samples tested using three-point bending and tensile tests, was not significantly different.

Polymer/Metall-Schichtsysteme mit Ausmaßen auf der Nanometer-Skala repräsentieren eine wichtige Materialklasse, welche für Untersuchungen von Grenzflächen- und Größeneffekten eine besondere Rolle spielen. Interessanterweise beobachtet man bei der Herstellung von Polymer/Metall-Systemen mit der gepulsten Laserdeposition spannungsinduzierte Wellenbildung in den Metallschichten, wenn diese auf einem Polymer mit einem niedrigen Elastizitätsmodul deponiert werden. Die Druckspannungen in den Metallschichten lassen sich aufgrund der hohen kinetischen Energien der deponierten Teilchen (100 eV) erklären. Die Biegebalkentheorie beschreibt dabei den Zusammenhang zwischen der ausgebildeten Wellenlänge und den Eigenschaften der beiden Komponenten. Aufgrund dieses Verständnisses ist es möglich, die gemessene Wellenlänge als Messmethode zur Bestimmung der mechanischen Eigenschaften der beiden Komponenten zu verwenden. Des Weiteren kann die Wellenlänge ganz gezielt durch Variation der Schichtdicke beider Komponenten eingestellt werden. Durch eine Steigerung des Elastizitätsmoduls der Polymerschicht ist es möglich, glatte Metallschichten ohne Wellenbildung herzustellen. Auf diese Weise lassen sich auch glatte, periodische Polymer/Metall-Schichtsysteme mit der gepulsten Laserdeposition herstellen, welche viele Möglichkeiten bieten sowohl für wissenschaftliche Fragestellungen als auch für Anwendungen.

L’exploration du tissu cutané est aujourd’hui limitée par le peu de méthodes dites quantitatives permettant de décrire objectivement les propriétés mécaniques du tissu cutané. L’élastographie permet une exploration locale d’un milieu et offre la possibilité pour certaines méthodes d’estimer quantitativement le module d’élasticité (module d’Young). Nous avons mis au point une technique d’élastographie ultrasonore impulsionnelle haute fréquence 1D (HF-TE) et haute résolution permettant une description micrométrique des propriétés mécaniques du tissu cutané pour des applications en cosmétique et en dermatologie. / Nowadays, exploration of cutaneous tissue is limited by the few number of available approaches, known as quantitative methods, allowing an objective description of the mechanical properties of skin tissue. Elastography allows a local exploration of a medium and offers the possibility for some strategies to quantitatively estimate the modulus of elasticity (Young’s modulus). A 1-D high-frequency ultrasonic transient elastography method (HF-TE) allowing a micrometric description of the mechanical properties of skin tissue has been designed for cosmetic and dermatological applications. An experimental system of high-frequency transient elastography has been developed : software, hardware and measurement methodology. The HF-TE technique has been validated using simulation and measurements in monolayer and bilayer calibrated phantoms developed in the laboratory. The Young’s modulus values measured in monolayer media were then compared with those measured by two others dynamic techniques.