A dedicated absorption spectroscopy system was set up using tungsten-halogen broadband source, optical fibers, sample holder, and a commercial spectrometer with CCD array. Analysis of noise present in the setup was carried out. Data processing was applied to the absorption spectra to reduce spectral noise, and improve the quality of the spectra and to remove the baseline level. The absorption spectra were measured for whole blood samples, separated components: plasma, saline, washed erythrocytes in saline and human whole blood with biomarkers - biocompatible nanodiamonds (ND). Blood samples had been derived from a number of healthy donors. The results prove a correct setup arrangement, with adequate preprocessing of the data. The results of blood-ND mixtures measurements show no toxic effect on blood cells, which proves the NDs as a potential biocompatible biomarkers.
Our aim is to optically monitor the delivery of the chemotherapy drugs for brain tumours, particularly used in the central nervous system (CNS) lymphoma therapy. In vivo monitoring would help to optimize the treatment and avoiding unnecessary medications. Moreover, it would be beneficial to be able to measure which of the multi-regimen drugs actually do penetrate and how well into the brain tissue.
There exist several potential optical measurement techniques to be utilised for the purpose. The most desired method would allow the detection of the drugs without using optical biomarkers as a contrast agent. In this case, for non-invasive sensing of the drug in the brain cortex, the drug should have a reasonably strong optical absorption band somewhere in the range between 600 nm and 1700 nm, and not directly coincident with the strong bands of haemoglobin or water. Alternatively, mid-infrared (MIR) range has the potential for invasive drug monitoring techniques.
In this paper, we report the optical properties of several chemotherapy drugs used in CNS lymphoma therapy, such as rituximabi, cyclophosphamide and etoposide. We measured their transmittance and reflectance spectra in near-infrared (NIR) range, particularly 900 nm − 2500 nm, to be considered when choosing the in vivo monitoring method to be developed. The absorption and scattering coefficients were retrieved from the measurements and applying Beer’s law. For the measurement of the sum of total transmission and reflection in NIR range we used integrating sphere with spektralo to enable calculation of the scattering coefficient.
In this article the simultaneous investigation of blood parameters by complementary optical methods, Raman spectroscopy and spectral-domain low-coherence interferometry, is presented. Thus, the mutual relationship between chemical and physical properties may be investigated, because low-coherence interferometry measures optical properties of the investigated object, while Raman spectroscopy gives information about its molecular composition.
A series of in-vitro measurements were carried out to assess sufficient accuracy for monitoring of blood parameters. A vast number of blood samples with various hematological parameters, collected from different donors, were measured in order to achieve a statistical significance of results and validation of the methods. Preliminary results indicate the benefits in combination of presented complementary methods and form the basis for development of a multimodal system for rapid and accurate optical determination of selected parameters in whole human blood. Future development of optical systems and multivariate calibration models are planned to extend the number of detected blood parameters and provide a robust quantitative multi-component analysis.
KEYWORDS: Blood, Raman spectroscopy, Data modeling, Spectroscopy, Plasma, Neodymium, Statistical analysis, In vivo imaging, Quantitative analysis, Chemical analysis
In this paper we present a proof-of-concept of a Raman spectroscopy-based approach for measuring the content of propofol, a common anesthesia drug, in whole human blood, and plasma, which is intended for use during clinical procedures. This method utilizes the Raman spectroscopy as a chemically–sensitive method for qualitative detection of the presence of a drug and a quantitative determination of its concentration. A number of samples from different patients with added various concentrations of propofol IV solution were measured. This is most equivalent to a real in-vivo situation. Subsequent analysis of a set of spectra was carried out to extract qualitative and quantitative information. We conclude, that the changes in the spectra of blood with propofol, overlap with the most prominent lines of the propofol solution, especially at spectral regions: 1450 cm-1, 1250- 1260 cm-1, 1050 cm-1, 875-910 cm-1, 640 cm-1. Later, we have introduced a quantitative analysis program based on correlation matrix closest fit, and a LOO cross-validation. We have achieved 36.67% and 60% model precision when considering full spectra, or specified bands, respectively. These results prove the possibility of using Raman spectroscopy for quantitative detection of propofol concentrations in whole human blood.
Fabrication process of thin boron-doped nanocrystalline diamond (B-NCD) microelectrode on fused silica single mode optical fiber has been investigated. The B-NCD films were deposited on the fibers using Microwave Plasma Assisted Chemical Vapor Deposition (MW PA CVD) at glass substrate temperature of 475 ºC. We have obtained homogenous, continuous and polycrystalline surface morphology with the mean grain size in the range of 100-250 nm and high sp3 content in B-NCD films. The films deposited on glass reference samples exhibit high refractive index (n≈2.05 at λ=550 nm) and low extinction coefficient. Furthermore, cyclic voltammograms (CV) were recorded to determine the electrochemical window and reaction reversibility at the B-NCD fibre-based electrode. Cyclic voltammetry (CV) measurements in aqueous media consisting of 5mM K3[Fe(CN)6] in 0.1M Na2SO4 demonstrated a width of the electrochemical window up to 2.5 V and relatively fast kinetics expressed by a redox peak splitting below 500 mV. Moreover, thanks to high-n B-NCD overlay, the coated fibers can be also used for enhancing sensitivity of long-period gratings (LPGs) induced in the fibers. The LPG is capable for measuring variations in refractive index of surrounding liquid by tracing shift in resonance appearing in transmitted spectrum. Possible combined CV and LPG-based measurements are discussed in this work.
This paper reports preliminary studies on use of Raman spectroscopy for investigation of blood. High quality blood spectra were recorded in-vitro with excitation wavelengths of 830 nm. Because of complex composition of the blood as well as by light attenuation and scattering in the tissues, spectra set up from wide, low-intensive Raman bands and intensive optical background. To get information about origin of bands in Raman spectra it is necessary to create phantom, which would show influence of this parameter and can be used to calibrate the Raman measurement system. Spectra of phantoms of selected blood components were acquired and discussed.
We have used reflectance spectroscopy for the in-situ, non-invasive monitoring of a thin oil film thickness during extrusion process of ceramic paste in capillary rheometer. Investigated pastes are disperse solid liquid systems prepared from the silicone oil AK106 (Wacker) and ceramic powder AlOOH. The thin oil film, extracted from the extruded paste, appears on walls of the rheometer die. A borosilicate view-port-glass provides optical access to the thin film inside the die. Reflectance spectroscopy enables the thin film thickness measurements by wideband spectral analysis of light back reflected from the sample. This spectrum includes extremes, which results from interference between beams reflected from glass-oil boundary and oil-paste boundary. Position and intensity of this extremes were determined by thickness of the thin film as well as refractive indices of the oil and the paste. Optoelectronic system dedicated for process monitoring by means of reflectance spectroscopy had been designed and built. The system comprises tungsten halogen lamp and fiber optic spectrometer. Optical signals are transmitted through bifurcated fibers, focusing optics and the view-port-window. Spectroscopic monitoring was carried out in VIS-NIR range from 400 to 900 nm as a function of extrusion velocity (0.01-5mm/s) and paste particle granulation (5-20 μm). Computer calculation, performed using dedicated software, enables fast determination of thickness even for reflectance spectra interfered by high noise level. Fast development of ceramic components technology requires detailed description of complex rheometric processes. Monitoring of the most important process parameter - oil layer thickness - enables pre-determination of rheometric factors required for proper paste extrusion and accurate shape filling.
Studies of application of Raman spectroscopy in measurement of important parameters of rheometric process, including profile of oil film thickness and composition of oil/paste system, were carried out. The films of silicone oil AK106 (Wacker) extracted from ceramic paste AlOOH were subjects of investigations presented in this paper. Boundary between oil film and extruded paste is not regular and ambiguous during the extrusion process of ceramic paste in capillary rheometer. Moreover, the pastes are scattering materials, what makes determination of the film thickness by conventional optical methods difficult. Preliminary Raman measurements were made separately for oil and paste samples in range extending from 50 to 3500 cm-1. Determination of main Raman bands assigned to oil, ceramics and glass showed that Raman spectroscopy enables discernment of these materials. During the next step, studies were conducted for a model sample of the oil spread on the paste, using Raman microscope. This device was equipped with long-working-distance objective which should enable remote measurements through a borosilicate, view-port-window in the wall of capillary rheometry die. Two methods of Raman determination of the thickness were compared. Results of analysis and experimental works suggest that one of them can be applied for in-situ monitoring of the extrusion process.
Analysis of important metrological problems of Raman investigation of solid state thin films is given in this paper. Raman studies of such films can be carried out as ex-situ measurements conducted for a sample outside the reaction vessel after manufacturing process or as in-situ monitoring of film deposition. First approach gives more possibilities of structure investigation while the second one can be used for optimisation of the manufacturing process parameters. One of the most important problems in the investigation of thin films is low level of the useful Raman signal, which is result of a small path length in the sample and, in some cases, optical properties of investigated materials. Moreover, for some applications, especially in-situ monitoring, it is difficult to excite the proper part of investigated structure. Consequently, sophisticated optical setups must be applied to ensure sufficient sensitivity of the measurement system. Raman systems able to use in investigation of thin solid films and monitoring of their deposition processes are presented. Results of Raman investigation of selected structures, starting from monocrystals through polycrystalline thin films to the amorphous ones are presented.
Principles of integrated optical sensors based on polarimetric interferometry are presented in the paper. A wide area of their applications in biochemistry includes monitoring of protein concentration in solutions, detection of antibodies as well as indirect investigation of chemical reactions, based on precise measurement of complex refractive index. In order to address a problem of irreversibility of wide group of biological processes and chemical reactions as well as to decrease cost of the sensors, authors propose to develop disposable measurement converters and to use optical components made from sol-gel derived hybrid polymers. The technology of hybrid materials synthesis and subsequent planar waveguides manufacturing as well as their properties are shown.
Mid-IR absorption and Raman scattering measurements were carried out for ferroelectric ceramics with composition of Ba(Ti1-xZrx)O3. The main aim of presented research was to analyze the ability of these complementary optical methods to estimate the efficiency of manufacturing process as well as to investigate the molecular strcuture of synthesized material. Task is very difficult, because of sophisticated structure of presented materials as well as technology of their manufacturing. Moreover, at the room temperature, the influence of difference in crystal phases as well as existence of remnants of oxides introduces significant changes to the spectrum. Results of presented research suggests that the efficiency of atom substitution can be investigated by means of optical spectroscopy.
KEYWORDS: Temperature metrology, Systems modeling, Sensors, Optical filters, Calibration, Black bodies, Radiometry, Scientific research, Data modeling, Algorithm development
Recent studies about non-contact temperature measurement concern passive multiband radiometric systems. These systems give a potential possibility of accurate temperature measurements in case of unknown and wavelength depended emissivity of the examined object. Modeling of such systems, what is usually the first stage of system designing, requires acceptance of several simplifications and approximations. In this paper an experimental verification of modeling result is performed. Based on developed experimental setup some tests are performed. It allows us to determine some systems parameters and whole system estimation.
Raman spectorscopy was applied to study the reactions between amine and epoxy groups, which had been expected to proceed during synthesis of hybrid polymer based on three monomers: 3-aminopropyltrimethoxysilane, 3-glycidyloxypropyl-trimethoxysilane and methacryloxy-propyltrimethoxysilane. Efficiency of the investigated reaction determines the molecular structure of the organic network and consequently - mechanical and optical properties of manufactured material. An optical system developed for the real-time Raman monitoring was connected with typical glass reaction vessel and non-invasive measurements were made. Additional FT-Raman investigation was carried out to confirm obtained results. Transformation of primary amine as well as epoxy ring opening was confirmed and role of catalyzers was discussed.
Permanent development of photonics stimulates a searching for new materials, which have better optical, mechanical and electrical properties. One of the new classes of materials with large application and development potential are hybrid polymers, synthesized in sol-gel technology. Thanks to incorporation of organic components into an in organic network, a combination of advantages of both class of materials became available. Properties of hybrids may be formed in wide range. These materials can be used in photonics to produce planar waveguides, lenses, Bragg gratings and components for integrated optics. Moreover, dielectric layers, coatings and packaging are made from hybrids. Additionally, research to apply them in optical fiber sensors (including bio-sensors) and solid state lasers is underway. However, to obtain a high quality product, a strict control of its molecular structure must be ensured. This is a very difficult task, because of a sophisticated structure of hybrid polymers. To address these problems, optical, non-destructive measurement techniques such as Raman and infrared spectroscopy were used. They are compementary methods, so their simultaneous application, as it was shown in this paper, can significantly increase the amoung of information about molecular structure of materials and process of their synthesis.
A Raman spectroscopy was used to diagnose a synthesis process of new class of materials - hybrid polymer thin films, dedicated to planar optical waveguides. Hybrids, made in sol-gel technology, have a great application potential, because their properties may be formed in wide range. However, to obtain high quality product, a strict control of the manufacturing process must be ensured. In our experiment, correctness of particular steps of the process as well as molecular structure of monomers, gel and thin films was investigated. The results of Raman mesurements showed that efficiency of two basic reactions should be improved. However, the structure of final product seems to be appropriate. To investigate full potential of Raman spectroscopy in process control, an experimental in-situ measurement was made in the real time, which allowed us to estimate the time required for the reaction.
A fiberoptic Raman spectroscopy system was adapted to remote measurements made in conditions typical for chemical industry. This technique was used to diagnose a process of synthesis of amine-epoxy based hybrid polymers, developed as a new class of adhesive materials for optics. Hybrids, manufactured in sol-gel technology, have a great application potential, because their properties may be formed in wide range. However, to obtain a high quality product, a strict control of the manufacturing process must be ensured. The main goal of research, presented in this paper, was to investigate the course and efficiency of the most important reactions, which takes part during the gelation -- the first step of the sol-gel process. An optical system developed for the real-time monitoring was connected with typical glass reaction vessel and non-invasive measurements were made. The results enabled to find the appropriate conditions for the reaction between amine and epoxy groups. Moreover, time of the hydrolysis of monomers and condensation of inorganic network was measured as well as efficiency of these reactions was proved to be very high.
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