| 5. | Osman Sayginer; Erica Iacob; Stefano Varas; Anna Szczurek; Maurizio Ferrari; Anna Lukowiak; Giancarlo C Righini; Oreste S Bursi; Alessandro Chiasera Design, fabrication and assessment of an optomechanical sensor for pressure and vibration detection using flexible glass multilayers (Journal Article) In: Optical Materials, vol. 115, pp. 111023, 2021, ISSN: 0925-3467. @article{SAYGINER2021111023,
title = {Design, fabrication and assessment of an optomechanical sensor for pressure and vibration detection using flexible glass multilayers},
author = {Osman Sayginer and Erica Iacob and Stefano Varas and Anna Szczurek and Maurizio Ferrari and Anna Lukowiak and Giancarlo C Righini and Oreste S Bursi and Alessandro Chiasera},
url = {https://www.sciencedirect.com/science/article/pii/S092534672100224X},
doi = {https://doi.org/10.1016/j.optmat.2021.111023},
issn = {0925-3467},
year = {2021},
date = {2021-01-01},
journal = {Optical Materials},
volume = {115},
pages = {111023},
abstract = {We introduce an easily implementable optomechanical device for pressure and vibration sensing using a multilayer structure on a flexible substrate. We present the design, fabrication and evaluation steps for a proof-of-concept device as well as optical glass components. The design steps include optical, mechanical, and optomechanical correlation simulations using the transfer matrix method, finite element analysis, geometric optics and analytical calculations. The fabrication part focuses on the deposition of multilayers on polymeric flexible substrates using the radio frequency sputtering technique. To investigate the quality of the glass coatings on polymeric substrates, atomic force microscopy and optical microscopy are also performed. Optical measurements reveal that, even after bending, there are no differences between multilayer samples deposited on the polymeric and SiO2 substrates. The performance assessment of the proof-of-concept device shows that the sensor resonance frequency is around 515 Hz and the sensor static response is capable of sensing from 50 Pa to 235 Pa.},
keywords = {Journal Article, Scopus Indexed},
pubstate = {published},
tppubtype = {article}
}
We introduce an easily implementable optomechanical device for pressure and vibration sensing using a multilayer structure on a flexible substrate. We present the design, fabrication and evaluation steps for a proof-of-concept device as well as optical glass components. The design steps include optical, mechanical, and optomechanical correlation simulations using the transfer matrix method, finite element analysis, geometric optics and analytical calculations. The fabrication part focuses on the deposition of multilayers on polymeric flexible substrates using the radio frequency sputtering technique. To investigate the quality of the glass coatings on polymeric substrates, atomic force microscopy and optical microscopy are also performed. Optical measurements reveal that, even after bending, there are no differences between multilayer samples deposited on the polymeric and SiO2 substrates. The performance assessment of the proof-of-concept device shows that the sensor resonance frequency is around 515 Hz and the sensor static response is capable of sensing from 50 Pa to 235 Pa. |
| 4. | Hao Chen; Alessandro Chiasera; Stefano Varas; Osman Sayginer; Cristina Armellini; Giorgio Speranza; Raffaella Suriano; Maurizio Ferrari; Silvia Maria Pietralunga Tungsten oxide films by radio-frequency magnetron sputtering for near-infrared photonics (Journal Article) In: Optical Materials: X, vol. 12, pp. 100093, 2021, ISSN: 2590-1478. @article{CHEN2021100093,
title = {Tungsten oxide films by radio-frequency magnetron sputtering for near-infrared photonics},
author = {Hao Chen and Alessandro Chiasera and Stefano Varas and Osman Sayginer and Cristina Armellini and Giorgio Speranza and Raffaella Suriano and Maurizio Ferrari and Silvia Maria Pietralunga},
url = {https://www.sciencedirect.com/science/article/pii/S2590147821000231},
doi = {https://doi.org/10.1016/j.omx.2021.100093},
issn = {2590-1478},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Optical Materials: X},
volume = {12},
pages = {100093},
abstract = {Tungsten oxide WO3-x is a transition metal oxide and a wide bandgap semiconductor, with a wide range of possible optical and photonic applications. In dependence on the fabrication techniques different stoichiometric ratios (x) and crystalline phases are obtained, which end up with an overall polymorph and extremely versatile material, characterized by tailorable dielectric properties. In particular, WO3-x thin film deposition by Radio-Frequency (RF) sputtering techniques provides a precise control of thickness, composition and nanostructure. In this work we introduce and discuss a specific process of deposition, that is magnetron RF-sputtering as a suitable way to grow WO3-x thin films with selected properties. Possibility of integrating WO3-x thin film on to one-dimensional (1D) photonic crystal structures is also explored. Films are transparent in the near and short-wavelength infrared optical spectral range. Their quality is assessed by morphological, structural and compositional characterizations. Dielectric properties are characterized by optical spectroscopy and ellipsometry, the latter also evaluates the degree of optical anisotropy of thin films in their crystalline phase. An 1D photonics bandgap structure is designed, formed by a SiO2–TiO2 multilayer and capped with a 450 nm-thick transparent WO3-x film, so that surface confinement and local enhancement of the optical field at 1416 nm in the topmost WO3-x layer is obtained.},
keywords = {Journal Article, Scopus Indexed},
pubstate = {published},
tppubtype = {article}
}
Tungsten oxide WO3-x is a transition metal oxide and a wide bandgap semiconductor, with a wide range of possible optical and photonic applications. In dependence on the fabrication techniques different stoichiometric ratios (x) and crystalline phases are obtained, which end up with an overall polymorph and extremely versatile material, characterized by tailorable dielectric properties. In particular, WO3-x thin film deposition by Radio-Frequency (RF) sputtering techniques provides a precise control of thickness, composition and nanostructure. In this work we introduce and discuss a specific process of deposition, that is magnetron RF-sputtering as a suitable way to grow WO3-x thin films with selected properties. Possibility of integrating WO3-x thin film on to one-dimensional (1D) photonic crystal structures is also explored. Films are transparent in the near and short-wavelength infrared optical spectral range. Their quality is assessed by morphological, structural and compositional characterizations. Dielectric properties are characterized by optical spectroscopy and ellipsometry, the latter also evaluates the degree of optical anisotropy of thin films in their crystalline phase. An 1D photonics bandgap structure is designed, formed by a SiO2–TiO2 multilayer and capped with a 450 nm-thick transparent WO3-x film, so that surface confinement and local enhancement of the optical field at 1416 nm in the topmost WO3-x layer is obtained. |
| 3. | Osman Sayginer; Rocco di Filippo; Aurelien Lecoq; Alessandra Marino; Oreste S Bursi Seismic Vulnerability Analysis of a Coupled Tank-Piping System by Means of Hybrid Simulation and Acoustic Emission (Journal Article) In: Experimental Techniques, 2020, ISSN: 1747-1567. @article{Sayginer2020c,
title = {Seismic Vulnerability Analysis of a Coupled Tank-Piping System by Means of Hybrid Simulation and Acoustic Emission},
author = {Osman Sayginer and Rocco di Filippo and Aurelien Lecoq and Alessandra Marino and Oreste S Bursi },
url = {https://doi.org/10.1007/s40799-020-00396-3},
doi = {10.1007/s40799-020-00396-3},
issn = {1747-1567},
year = {2020},
date = {2020-09-01},
journal = {Experimental Techniques},
abstract = {In order to shed light on the seismic response of complex industrial plants, advanced finite element models should take into account both multicomponents and relevant coupling effects. These models are usually computationally expensive and rely on significant computational resources. Moreover, the relationships between seismic action, system response and relevant damage levels are often characterized by a high level of nonlinearity, which requires a solid background of experimental data. Vulnerability and reliability analyses both depend on the adoption of a significant number of seismic waveforms that are generally not available when seismic risk evaluation is strictly site-specific. In addition, detection of most vulnerable components, i.e., pipe bends and welding points, is an important step to prevent leakage events. In order to handle these issues, a methodology based on a stochastic seismic ground motion model, hybrid simulation and acoustic emission is presented in this paper. The seismic model is able to generate synthetic ground motions coherent with site-specific analysis. In greater detail, the system is composed of a steel slender tank, i.e., the numerical substructure, and a piping network connected through a bolted flange joint, i.e., the physical substructure. Moreover, to monitor the seismic performance of the pipeline and harness the use of sensor technology, acoustic emission sensors are placed through the pipeline. Thus, real-time acoustic emission signals of the system under study are acquired using acoustic emission sensors. Moreover, in addition to seismic events, also a severe monotonic loading is exerted on the physical substructure. As a result, deformation levels of each critical component were investigated; and the processing of acoustic emission signals provided a more in-depth view of the damage of the analysed components.},
keywords = {Journal Article, Scopus Indexed},
pubstate = {published},
tppubtype = {article}
}
In order to shed light on the seismic response of complex industrial plants, advanced finite element models should take into account both multicomponents and relevant coupling effects. These models are usually computationally expensive and rely on significant computational resources. Moreover, the relationships between seismic action, system response and relevant damage levels are often characterized by a high level of nonlinearity, which requires a solid background of experimental data. Vulnerability and reliability analyses both depend on the adoption of a significant number of seismic waveforms that are generally not available when seismic risk evaluation is strictly site-specific. In addition, detection of most vulnerable components, i.e., pipe bends and welding points, is an important step to prevent leakage events. In order to handle these issues, a methodology based on a stochastic seismic ground motion model, hybrid simulation and acoustic emission is presented in this paper. The seismic model is able to generate synthetic ground motions coherent with site-specific analysis. In greater detail, the system is composed of a steel slender tank, i.e., the numerical substructure, and a piping network connected through a bolted flange joint, i.e., the physical substructure. Moreover, to monitor the seismic performance of the pipeline and harness the use of sensor technology, acoustic emission sensors are placed through the pipeline. Thus, real-time acoustic emission signals of the system under study are acquired using acoustic emission sensors. Moreover, in addition to seismic events, also a severe monotonic loading is exerted on the physical substructure. As a result, deformation levels of each critical component were investigated; and the processing of acoustic emission signals provided a more in-depth view of the damage of the analysed components. |
| 2. | Osman Sayginer; Alessandro Chiasera; Lidia Zur; Stefano Varas; Lam Thi Ngoc Tran; Cristina Armellini; Maurizio Ferrari; Oreste S Bursi Fabrication, modelling and assessment of hybrid 1-D elastic Fabry Perot microcavity for mechanical sensing applications (Journal Article) In: Ceramics International, vol. 45, no. 6, pp. 7785–7788, 2019, ISSN: 0272-8842. @article{Sayginer2019b,
title = {Fabrication, modelling and assessment of hybrid 1-D elastic Fabry Perot microcavity for mechanical sensing applications},
author = {Osman Sayginer and Alessandro Chiasera and Lidia Zur and Stefano Varas and Lam Thi Ngoc Tran and Cristina Armellini and Maurizio Ferrari and Oreste S Bursi},
doi = {10.1016/j.ceramint.2019.01.083},
issn = {0272-8842},
year = {2019},
date = {2019-04-15},
journal = {Ceramics International},
volume = {45},
number = {6},
pages = {7785--7788},
publisher = {Elsevier},
abstract = {1-D multilayer dielectric films consisting of seven pairs of SiO2 and TiO2 alternating layers are deposited on a SiO2 substrate using the radio frequency sputtering technique. The thicknesses of the film layers are chosen to reflect the visible radiation around 650 nm. An elastic microcavity layer made of Polydimethylsiloxane was sandwiched between two Bragg reflectors. A fabrication process was then developed for elastic microcavity in order to tailor the thickness, establish the surface planarity and to increase reproducibility of the samples. Optical transmittance of the single Bragg reflector and the microcavity were both simulated and measured. A comparison between measurement data and Transfer Matrix Method calculations shows a favourable correlation. Furthermore, in order to assess the suitability of the microcavity as a force sensor, transmittance measurements were carried out as a function of the applied forces. The change in the elastic microcavity thickness due to applied forces resulted in cavity resonance peak shifts proportional to the applied forces.},
keywords = {Journal Article, Scopus Indexed},
pubstate = {published},
tppubtype = {article}
}
1-D multilayer dielectric films consisting of seven pairs of SiO2 and TiO2 alternating layers are deposited on a SiO2 substrate using the radio frequency sputtering technique. The thicknesses of the film layers are chosen to reflect the visible radiation around 650 nm. An elastic microcavity layer made of Polydimethylsiloxane was sandwiched between two Bragg reflectors. A fabrication process was then developed for elastic microcavity in order to tailor the thickness, establish the surface planarity and to increase reproducibility of the samples. Optical transmittance of the single Bragg reflector and the microcavity were both simulated and measured. A comparison between measurement data and Transfer Matrix Method calculations shows a favourable correlation. Furthermore, in order to assess the suitability of the microcavity as a force sensor, transmittance measurements were carried out as a function of the applied forces. The change in the elastic microcavity thickness due to applied forces resulted in cavity resonance peak shifts proportional to the applied forces. |
| 1. | N Moharrami; DJ Langton; O Sayginer; SJ Bull Why does titanium alloy wear cobalt chrome alloy despite lower bulk hardness: A nanoindentation study? (Journal Article) In: Thin Solid Films, vol. 549, pp. 79–86, 2013, ISSN: 0040-6090. @article{moharrami2013does,
title = {Why does titanium alloy wear cobalt chrome alloy despite lower bulk hardness: A nanoindentation study?},
author = {N Moharrami and DJ Langton and O Sayginer and SJ Bull},
doi = {10.1016/j.tsf.2013.06.020},
issn = {0040-6090},
year = {2013},
date = {2013-01-01},
journal = {Thin Solid Films},
volume = {549},
pages = {79--86},
publisher = {Elsevier},
abstract = {Titanium-based and cobalt-chrome alloys have been widely used in orthopaedic applications as these materials can significantly enhance the quality of human life as implant materials. The longevity of these materials is highly influenced by their mechanical properties. In some devices cobalt chrome components articulate with titanium alloy counter faces (e.g. in the taper connections of stems and femoral heads in modern modular designs) and damage has been reported of the harder cobalt chrome by the softer titanium alloy component. This study attempts to understand why this might occur by investigating bulk and surface mechanical properties (such as hardness and Young's modulus) of a number of hip implants and test samples using a Hysitron Triboindenter. AFM images were also obtained to determine the contact area and hence, pile-up correction factors.
The results were compared for samples before being used in the body, to account for surface mechanical response due to implant manufacture, and after, to account for the materials response to long-term cyclic loads. To assess the effects of oxidation, the alloys were treated electrochemically with Sodium-Chloride (NaCl) solution at body temperature. It was found that titanium oxidised preferentially compared with cobalt-chrome alloys. Furthermore, the oxidised titanium showed significantly higher hardness values therefore damaging the un-oxidised cobalt-chrome material. The implications for device design and manufacture are discussed.},
keywords = {Journal Article, Scopus Indexed},
pubstate = {published},
tppubtype = {article}
}
Titanium-based and cobalt-chrome alloys have been widely used in orthopaedic applications as these materials can significantly enhance the quality of human life as implant materials. The longevity of these materials is highly influenced by their mechanical properties. In some devices cobalt chrome components articulate with titanium alloy counter faces (e.g. in the taper connections of stems and femoral heads in modern modular designs) and damage has been reported of the harder cobalt chrome by the softer titanium alloy component. This study attempts to understand why this might occur by investigating bulk and surface mechanical properties (such as hardness and Young's modulus) of a number of hip implants and test samples using a Hysitron Triboindenter. AFM images were also obtained to determine the contact area and hence, pile-up correction factors.
The results were compared for samples before being used in the body, to account for surface mechanical response due to implant manufacture, and after, to account for the materials response to long-term cyclic loads. To assess the effects of oxidation, the alloys were treated electrochemically with Sodium-Chloride (NaCl) solution at body temperature. It was found that titanium oxidised preferentially compared with cobalt-chrome alloys. Furthermore, the oxidised titanium showed significantly higher hardness values therefore damaging the un-oxidised cobalt-chrome material. The implications for device design and manufacture are discussed. |
