Shema de realizare a proiectului 19 15 01 01 - Anul 2019 - Etapa a II-a
Faza nr. 11b
Responsabil: Dr. E. Axente
Termen de predare: 13.09.2019
Titlu: "Proiectare, caracterizare si testare a unei platforme pentru controlul curgerii in dispozitive microfluidice - Partea II (Caracterizarea si testarea)"
Abstract: In this project we have realized the design of an inovative microfluidic platform, in both a basic and a complex configuration, but also its characterisation and testing for controlled flow of two different liquids. We also completed a technological protocol for microfabrication of a hybrid (glass - PDMS) microfluidic device, that can be used for the controlled mixing of liquids. This biochip was further assembled and connected to the perfusion system, and specific flow configurations were thus investigated.
Moreover, we have performed an UV-Vis spectrophotometric investigation of different relevant biological solutions, as e.g. fetal bovine serum, cellular medium, water and theirs dilutions. Measurements on 11 different concentrations of the solutions were performed, in order to identify the maximum absorbance values for each dilution. The goal of this analyses was to build up calibration curves, to be further used as references for the in-situ and real-time concentration measurements during the perfusion of the biochips. Possible applications are related to controlled mixing of different biological solutions containing equal or different drugs concentration for biomedical applications or for the synthesis of new nanomaterials by performing controlled chemical reactions in chips.
Abstract grafic:
Faza nr. 12
Responsabil: Dr. A. Petris
Termen de predare: 13.09.2019
Titlu: "Procese neliniare de ordinul trei excitate in cristale de GaN de pulsuri laser ultrascurte"
Abstract: Gallium nitride (GaN) is a binary III-V class compound semiconductor with a direct large photonic band gap (Eg= 3,39 eV) important for photonics due to its optical (linear and non-linear), chemical, mechanical properties and the possibility of integration with Si.
The photon energy at λ = 1550 nm used in this study, Eph = 0,8 eV, is four time less than the photonic band gap of GaN crystal. For this wavelength, not only that the single photon absorption process, but even the two or three photon absorption processes cannot excite resonant transitions in GaN. Therefore, in this case, the induced optical nonlinearity is nonresonant. The nonlinear optical response of electronic origin induced in GaN by photons at λ = 1550 nm, which is responsible for the third harmonic generation, is obtained by processes that imply virtual energy levels, being extremely fast (response time < 1 fs).
In this study we have investigated the ultrafast third-order optical nonlinearity induced in a GaN crystal by high-repetition-rate ultrashort laser pulses (120fs) at 1550 nm using a direct optical method – third harmonic generation. Despite the possibility of inducing other cumulative nonlinear optical processes of thermo-optical origin during irradiation with high-repetition-rate ultrashort pulses, they cannot be hold responsible for the third harmonic generation, the ultrafast electronic process being solely responsible for. Thus, the optical third harmonic generation is an appropiate method to investigate the ultrafast nonlinear response, leading to a direct determination of the third-order nonlinear optical susceptibility, merit only of the electronic processes induced by light in the investigated material.
The third harmonic generation in the GaN crystal has been obtained using an experimental setup designed and assembled in our lab. The very small optical powers of the third harmonic (~ pW) have been accurately measured by a method developed by us, in which a common camera is used as an ultrasensitive powermeter by calibrating it according to a special procedure introduced by us.
We have determined the parameters of the refractive nonlinearity in GaN, namely the third-order optical susceptibility and the corresponding nonlinear refractive index.
The study of the nonlinear optical response in GaN is of particular importance, both to the investigation of light-matter interaction as well as to photonic functionalities based on nonlinear optical proc esses induced by light.
Abstract grafic:
The experimental dependence of the third harmonic intensity ITH generated in GaN crystal on the intensity IFH of the incident fundamental beam (λ=1550 nm, τ ~ 120 fs) fitted by a third grade polynomial. The ultralow average power (~pW) of the TH beam is measured by processing the TH beam spot images, acquired using a common camera, specially calibrated by using a procedure developed by us.
Inset: the image of the TH beam spot for IFH= 2.29 GW/cm2 GW/cm2 and for an exposure time of 0.96 ms.
Faza nr. 13
Responsabil: Dr. C. surdu-Bob
Termen de predare: 14.10.2019
Titlu: "Sinteza si caracterizarea straturilor cu continut de nitrura de carbon folosind o plasma anodica de inalta tensiune"
Abstract: The project focused on exploitation of new capabilities of the High Voltage Anodic Arc, the new plasma source for controlled deposition of different allotropic forms of Carbon Nitride.
The increased interest on carbon nitrides coatings is due to their physical, mechanical, electrical, optical and opto-electrical exceptional properties. Moreover, these properties are stable even in extreme conditions of temperature, chemical corrosive media and humidity.
During this phase of project, the posibility of synthesising thin films containing carbon nitrides was investigated. As a part of this investigations, a series of different electrodes configurations of the Compound – High Voltage Anodic Arc Plasma (C-HVAP) system were studied from the point of view of process parameters (electrical, gas flow) influence on the films composition. The deposited films were optically characterized and also their hardness measured. XPS was used in order to determine their surface composition and chemical bonding.
The results obtained from XPS revealed a major difference in films composition when using different electrodes configurations for deposition. When using localized nitrogen-carbon plasma the amount of C-N chemical bondings did not excedeed 3% of the total C,N,O bondings while when using the configuration in which only the carbon plasma was localized, the C-N chemical bonding increased to values of 10 to 28 % of the total C,N,O bondings. The XPS spectra highlited the presence of both triple bondings characteristic to βC3N4 and double bondings characteristic to grafitic C3N4; their ratio varied as a function of experimental process parameters. Films hardness was measured using a 10 g weight and the results obtained showed a corespondence between hardness and composition; an increase from 840 HV of the Si substrate, up to 1081 HV when high C – N bonding present in the film. It should be mentioned that when using the configuration in which only the carbon plasma is localized the presence of different metallic impurities was noticed along with a significant increase in oxygen content; the metallic impurities were sputtered from all surfaces within the chamber.
The UV-VIS spectroscopy measurements shows similar transmision spectra for the films deposited using the same electrode configuration, the observed small variations in the intensity being related to films thickness. The IR-ATR measurements performed on the films deposited using localized nitrogen-carbon plasma shows absorbtion peaks characteristic to C-O and/or C-N simple bonding but also to C=N ones.
As a conclusion, thin films of CNx were succesfully synthesised for the first time using the C-HVAP plasma source. The presence of metallic impurities were registered as a drawback of this plasma source. Further research will be directed towards the improvement of electrodes configuration in order to overcome the issue and also to increase βC3N4 content.
Abstract grafic:
Faza nr. 14
Responsabil: Dr. L. Gheorghe
Termen de predare: 14.10.2019
Titlu: "Dezvoltarea de cristale Nd:LGSB pentru emisie laser eficientă în domeniul spectral 1µm. Ceramici transparente de tip granat dopate cu ioni de pământuri rare pentru infrarosu apropiat."
Abstract: A. Single crystals of La0.64Gd0.41Sc2.95(BO3)4 - LGSB doped with 5.0 at.% Nd3+ ions (Nd:LGSB) were grown from the melt by the Czochralski method, for the first time to our knowledge. Chemical composition of the raw materials (starting melt composition), pulling and rotation rates, crystal growth direction and the cooling rate to room temperature were optimized, and the chemical composition of the grown crystals was determined to be La0.721Nd0.046Gd0.452Sc2.781(BO3)4. The obtained crystals have dimensions of about 10 - 12 mm in diameter and 25 - 30 mm in length, they are of very good optical quality, non-hygroscopic and chemically stable. The nonlinear optical (NLO) and spectroscopic properties were determined, and the laser performances in quasi-continuous wave regime (pulse duration of 250 μs and repetion rate of 2 Hz) were also evaluated. Two uncoated samples oriented parallel and, respectively, perpendicular to the c-axis of the crystal, with aperture of about 3.0 × 3.0 mm2 and thicknesses of 6.14 mm and 2.96 mm, respectively, were investigated. High-efficiency laser emission at λem = 1061.97 nm (Δλem = 1.59 nm) was obtained for both samples. The highest slope efficiency (ηsa) was obtained for a mirror with transmission T = 5%, and the obtained values are 71% and 73% (with respect to the absorbed energy) for the sample oriented parallel and, respectively, perpendicular to the c-axis of the crystal, proving the good quality of the Nd:LGSB grown crystals.
B. In Romania, polycrystalline 1.0 at.% Nd:YAG and 5.0 at.% Yb:YAG transparent ceramics were obtained for the first time by solid-state reaction and vacuum sintering method. Structural, morphological and optical investigations confirm their potential as a laser gain media for NIR laser emission.
Abstract grafic:
Faza nr. 15
Responsabil: Dr. V. Dinca
Termen de predare: 14.10.2019
Titlu: "Dezvoltarea de bio‐platforme biocompatibile micro si nanostructurate pentru studiul efectului topografiei asupra celulelor mamaliene ‐obtinerea si analiza morfologica si structurala de substraturi structurate prin ablatie/texturare laser"
Abstract: Obtaining and analyzing polymeric microstructured surfaces that can lead to an understanding of extracellular factors on cellular response in vitro, is of particular importance in biomedical applicationsespecially for implantable devices. It is essential to understand how the characteristics of the material can influence the cellular response, implicitly the acceptance or rejection of the implant. So-called artificially obtained biomimetic surfaces can also have an impact on cell biology, by understanding the mechanisms that lead to adhesion, cell apoptosis. Therefore, the characteristics of the materialsbut especially of the surface, must be correlated with both the cell type and the intended application. Micro- and nano-fabrication methods offer benefits in developing 2D or 3D topographies in addressing current challenges in tissue engineering. The production of such supports with variable topography is of interest for the study of the influence of substrate properties on the cellular functionsleading the scientific community to the recent development of new techniques of microfabrication of substrates (eg lithography, replication, laser texture, etc.). In this context the objective of this phase was to obtain multidimensional micro-structured surfaces in polycarbonate by ablation using a laser-assisted excimer mask with variable attenuation. Polymer microstructured surfaces have been obtained and characterized for use in the study of the effect of surface characteristics on mammalian cell response. The presented results showed that microtopography of the substrate is an important factor in the cellular response, offering interesting perspectives regarding the use of topography for designing future tissue engineering systemsbut also for studying the cellular mechanisms during normal development and / or tumor progression.
Abstract grafic:
Faza nr. 16
Responsabil: Dr. N. Scarisoreanu
Termen de predare: 14.11.2019
Titlu: "Investigarea proprietatilor fizico-chimice prin experimente de pompaj cu laseri cu pulsuri ultrascurte ale micro-nanostructurilor obtinute in conditii de constrangeri structurale si chimice"
Abstract: During this stage thin films and heterostructures of dielectric materials were obtained and they were investigated from a morphological, optical and dielectric point of view. From the morphological point of view we have found notable differences between different types of dielectric thin layers, with the variation of the RMS value from 0.7 nm to 17 nm. Regarding the refractive index, the values obtained were comparable with specialized literature for all three dielectric materials, and from the point of view of the extinction coefficient in the case of TiO2 thin films it is high in the region of small wavelengths (normal values because TiO2 has a prohibited band value of 3.23 eV both in the structure of the routes and in the anatase structure). Regarding the YSZ and HfO2 thin films, the optical absorption (the extinction coefficient) is small over all the measured range with a slight increase in wavelengths in the ultraviolet area. The HfO2 / YSZ heterostructures exhibited dielectric behavior superior to the individual thin films, the frequency dispersion of the dielectric constant and the dielectric losses occurring with the increase of the applied electric field frequency suggesting the existence of intrinsic structural defects that lead to the increase of leakage currents. The same behavior was observed in the case of individual dielectric thin films. The tests performed for determining the laser ablation threshold showed higher values of the destruction threshold in the case of pulse duration of the order ns, due to a lower energy intensity applied to the thin films compared to the fs pulses. The highest value of the destruction threshold was obtained for the hafnium oxide heterostructure deposited on yttrium stabilized zirconium oxide, for which values of 0.82 J/cm2 were obtained.
Abstract grafic:
Faza nr. 17
Responsabil: Dr. G. Socol
Termen de predare: 14.11.2019
Titlu: "Dezvoltarea unui dispozitiv inovativ cu fibră optică bazat pe rezonanță plasmonică de suprafață (FO-SPR) pentru monitorizarea în timp real a interacţiilor bio-/moleculare"
Abstract: Obtaining and analyzing polymeric microstructured surfaces that can lead to an understanding of extracellular factors on cellular response in vitro, is of particular importance in biomedical applicationsespecially for implantable devices. It is essential to understand how the characteristics of the material can influence the cellular response, implicitly the acceptance or rejection of the implant. So-called artificially obtained biomimetic surfaces can also have an impact on cell biology, by understanding the mechanisms that lead to adhesion, cell apoptosis. Therefore, the characteristics of the materialsbut especially of the surface, must be correlated with both the cell type and the intended application. Micro- and nano-fabrication methods offer benefits in developing 2D or 3D topographies in addressing current challenges in tissue engineering. The production of such supports with variable topography is of interest for the study of the influence of substrate properties on the cellular functionsleading the scientific community to the recent development of new techniques of microfabrication of substrates (eg lithography, replication, laser texture, etc.). In this context the objective of this phase was to obtain multidimensional micro-structured surfaces in polycarbonate by ablation using a laser-assisted excimer mask with variable attenuation. Polymer microstructured surfaces have been obtained and characterized for use in the study of the effect of surface characteristics on mammalian cell response. The presented results showed that microtopography of the substrate is an important factor in the cellular response, offering interesting perspectives regarding the use of topography for designing future tissue engineering systemsbut also for studying the cellular mechanisms during normal development and / or tumor progression.
Abstract grafic:
Faza nr. 18
Responsabil: Dr. B. Mitu
Termen de predare: 14.11.2019
Titlu: "Abordari privind sinteza prin tehnici combinate cu plasma de materiale nanocompozite pe baza de matrici polimerice pentru aplicatii biomedicale"
Abstract: In the present stage of the project we aimed to synthesise metal-polymer nanocompozite materials by combined plasma based tehniques. The investigated composition was based on Silver and amorphous fluorurated material, due to the well-known antimicrobian properties of Ag, especially as nanoparticles, as well as the antifouling properyies of the fluorurated surfaces, which impede bacterial strains to adhere onto surface and form biofilms. In the presented combination, Ag was obtained by physical vapor deposition methods, respecively using magnetron sputtering in calssical configuration, but also in the modern version with gas aggregation source. In order to obtain the polymeric material in the nanocompozites, which plays the role of matrix in the investigated combination, we make use of magnetron sputtering from polytetrafluorethylene (PTFE) target, orplasma assisted chemical vapor deposition. Experimental variants included in this case the deposition from Ar/CH4/SF6 admixture, or a combined process of deposition in Ar/CH4 atmosphere, followed by plasma treatment in Ar/SF6 to fluorurate the initial obtained amorphous hiderogenated carbon. The results evidence the formation of nanostructured Ag with typical dimension of few nm and narrow log normal distribution, while significant compositional variation were achieved for the polymeric matrix of fluorurated carbon.
Abstract grafic:
a) c) AgNP obtained onto Si substrate by magnetron sputtering with gas aggregation – particles with dimension in the range 5-20 nm.
b) d) Ag NP obtained by classical magnteron sputtering onto a-CF surface -typical dimension around 10 nm
Atomic Force Microscopy (AFM) investigations of nanocomposite materials revealing the
presence of Ag nanoparticles by surface topography
a) c) a-CF material obtained by magnetron sputtering from PTFE target, revealing chemical bonds of C-C with a predominance of CFx bonds.
b) d) a-CF material obtained by Plasma assisted chemical vapor deposition from Ar/CH4 admixture and Ar/SF6 treatment, showing predominance of C-C bonds with small content of CFx and oxygen related bonds.
Chemical composition of amorphous fluorurated carbon as determined by X-ray
Photoelectron Spectoscopy (XPS) investigations
Faza nr. 19
Responsabil: Dr. N. Pavel
Termen de predare: 9.12.2019
Titlu: "Influenta distributiei spatiale a fasciculelor laser asupra aprinderii diferitelor amestecuri de combustibili. Posibilitati de utilizare a fibrelor optice si laserilor cu fibra optica in aprinderea cu laser. Pulsuri ultrascurte cu aplicatii in industrie si medicina"
Abstract: In this project report results on laser ignition of air-CH4 (methane) mixtures with stoichiometric concentration (λ∼1), lean air-CH4 mixtures (λ∼1.1 to 1.6) and reach air-CH4 mixtures (with λ up to 0.9) are reported. The ignition was done in a static chamber of 0.2 dm3 volume and 1 bar initial pressure, using a laser spark plug device, in a single point, but also with a laser with four beams that were focused in four different positions. For each experiment, pressure curves were recorded. The limits of the air-CH4 mixtures for which the laser ignition could be achieved were determined. The second set of experiments aimed the laser operation in quasi-mode-locking (QML) and continuous mode-locking (CML) of a Nd: LGSB laser crystal (4.6-at.% Nd, 3 mm thick), pumped with diode laser at 807 nm. The laser pulses in the CML regime had a duration of 1.43 ps and the energy of 1.63 nJ at 118 MHz repetition rate; the average power was 0.19 W. The third set of results describes the laser emission obtained from an Yb-doped optical fiber, YDCF-Yb-30/250P-FAC (CorActive High-Tech, Inc., Canada); the fiber had a core fiber diameter 30 μm whereas the clad had a regular octahedron shape of 250-μm diameter. The performances of the laser emission under quasi-continuous pumping were determined for different fiber lengths. For example, a fiber with a length of 1.2 m emitted laser pulses with the energy Ep= 7.85 mJ for an absorbed energy of the pump pulse Eabs= 14.4 mJ (the optical efficiency with respect to the absorbed pump pulse energy Eabs was of ηoa∼0.54); the slope of the laser emission, with respect to Eabs, was ηsa∼0.63.
Abstract grafic:
Faza nr. 20a
Responsabil: Dr. I. Tiseanu
Termen de predare: 9.12.2019
Titlu: "Analiza cantitativa a caracteristicilor pulberilor metalice și a porozității componentelor realizate prin manufacturare aditivata prin microtomografie de raze X și procesare de imagini. Comparație cu analiza 2D a imaginilor metalografice - partea I - Analiza cantitativa"
Abstract: The main objectives of this study consisted in the development of a methodology that uses the X-ray industrial tomography in all stages of performing the additive manufacturing based on laser processing of metallic powders.
In the first step, metallic powders were analyzed from qualitative and quantitative point of view in the additive manufacturing with high-power laser. Nonconformities of shape and composition were identified, as well as the detailed distribution of the particles size and sphericity. The micro-morphological characteristics of the particles of the metal powder were very useful in optimizing the manufacturing process.
In the second step, X-ray tomography has also been used as a method of rapid prototyping by iterative comparisons between the initial CAD model and the 3D model of tomographic reconstruction. Thus, it was possible to determine the nominal deviations of the overall CAD model as well as the degree of filling on the samples. It should be noted that the last information is almost impossible to determine by classical metrological methods.
Additionally, we proposed and tested a possible solution to assist the restauration of industrial components by laser cladding via X-ray tomography. By CT scanning of the defect component one extracts the CAD model of the region of interest for laser cladding restauration. This CAD model serves as the input data for the laser processing. Also, the industrial tomography was applied as quality control monitoring instrument during the restauration process. By 3D tomography one detects the typical defects as pores, lack of adhesion with the substrate material, various impurity inclusions throughout the sample volume, etc.
Finally, the superiority of the non-destructive control by means of industrial tomography over the metallographic analysis was demonstrated by detailed comparisons between 2D tomographic sections and equivalent metallographic images. One shows that a great number of small defects were missed by the laborious cutting and polishing operations.
Abstract grafic:
Faza nr. 21
Responsabil: Dr. M. Demeter
Termen de predare: 9.12.2019
Titlu: "Hidrogeluri polimerice biodegradabile cu proprietăți superabsorbante pentru aplicații în medicina regenerativă"
Abstract: At this stage of the project, superabsorbent hydrogels were obtained from biodegradable polymers based on collagen, PVP and PEO, which can be used as dressings for the healing of soft tissue. The polymer mixture was cross-linked with electron beams using inert argon atmosphere. The hydrogels obtained were characterized following sol-gel analysis, radiochemical cross-linking and degradation yields, determination of the swelling degree and stability in simulated physiological environments, kinetic of swelling in deionized water, rheological analysis and determination of hydrogel network parameters (the molecular weight between two cross-linking points, MC; mesh size, ξ and crosslinking density, Ve). The composition of superabsorbent hydrogels was investigated by FT-IR spectroscopy. The collagen/PVP/PEO hydrogels exhibited a higher gel fraction depended on the applied irradiation dose. The results showed in the case of collagen/PVP hydrogel, that the swelling degree at 25 kGy, has the value of 4000% and decreases by approximately 2.5 times, when PEO is added to the composition of the hydrogel.
The properties of the hydrogels obtained from collagen, PVP and PEO, confirm that they can be used for different types of applications, such as: dressings or controlled release systems of different medicinal products or as polymeric matrix in the tissue engineering of soft tissues. The overall properties of these hydrogels can be adjusted by varying the irradiation parameters and the polymeric composition, so as to obtain a final product with controlled properties and at the same time with good quality for the intended purpose.
Abstract grafic:
Faza nr. 22
Responsabil: Dr. Sf. Irimiciuc
Termen de predare: 9.12.2019
Titlu: "Dezvoltarea și implementarea tehnicilor de diagnoză electrică aplicate plasmelor tranziente. Sonda Langmuir pentru măsurători spațio-temporale"
Abstract: In the framework of the project the creation of a new research and development direction was aimed by producing, adapting and testing an electrical diagnostic technique for the monitoring the pulsed laser deposition process. The dynamics of a transient plasma generated by ns-laser ablation of a Ag target was investigated by means of Langmuir probe method. The Langmuir probe was developed in the framework of the project and was tested in each step of the development to ensure the accuracy of the measurements. Both angular and time-resolved approached were implemented in order to study the dynamics of the ejected charged particle. The angular measurements revealed a decrease in both density and kinetic energy of the ejected ions while for the electron a more uniform distribution. The floating probe measurements revealed the presence of multiple plasma structures containing both atoms and ions expanding with different velocities, showcasing the presence of Coulomb explosion as a main ejection mechanism. The time resolved measurements revealed that the electrons have a considerable longer life time, of about one order of magnitude. By implementing the sweeping method, we determined a series of plasma parameters at various moments in time during the plasma expansion. The newly developed diagnostic technique showed good reproducibility in terms of recorded signals and also showed promise for its implementation in more complex geometries.
Abstract grafic:
