Polarimetric and spectral imaging approach for meat quality control and characterization of biological tissues

Abstract In this chapter, different experimental and analytical methodologies were applied to investigate light-tissue interaction and analyze optical and polarization properties over time. The obtained results were utilized in biomedical and food science applications. In this chapter, soft biological tissues (pork samples) were selected as a biological tissue due to their similarity to human tissue. First, the relative spectral changes of absorbance were studied by applying two different custom-built configurations. A Monte Carlo modeling and principal component analysis (PCA) method were applied further to the absorbance dataset to provide thorough studies for a spectroscopic approach. Second, a novel application of Mueller matrix (MM) imaging polarimetry was pioneered to visualize the dynamics of the tissue polarization properties over time with a custom-built Mueller matrix imaging polarimeter (MMIP). Frequency distribution histograms (FDHs) and the changes in the statistical moments of the MM elements were analyzed over time to provide qualitative and quantitative information of the tissue polarization properties. Finally, a new Stokes polarimetry was introduced to examine optically thin histological sections from optically anisotropic biological tissues with different morphological structures. In summary, in spectroscopic and imaging polarimetry approaches, prominent changes in optical properties of the examined soft biological tissues were discriminated over time. The obtained results are promising in the development of a novel non-destructive tool for monitoring biological tissues for application in biomedical applications and the food industry. The Stokes polarimetry method can provide a comparative analysis of different polarimetric techniques and prove the diagnostic potential of Stokes correlometry of pathological changes in the orientation phase structure of biological tissues.Abstract In this chapter, different experimental and analytical methodologies were applied to investigate light-tissue interaction and analyze optical and polarization properties over time. The obtained results were utilized in biomedical and food science applications. In this chapter, soft biological tissues (pork samples) were selected as a biological tissue due to their similarity to human tissue. First, the relative spectral changes of absorbance were studied by applying two different custom-built configurations. A Monte Carlo modeling and principal component analysis (PCA) method were applied further to the absorbance dataset to provide thorough studies for a spectroscopic approach. Second, a novel application of Mueller matrix (MM) imaging polarimetry was pioneered to visualize the dynamics of the tissue polarization properties over time with a custom-built Mueller matrix imaging polarimeter (MMIP). Frequency distribution histograms (FDHs) and the changes in the statistical moments of the MM elements were analyzed over time to provide qualitative and quantitative information of the tissue polarization properties. Finally, a new Stokes polarimetry was introduced to examine optically thin histological sections from optically anisotropic biological tissues with different morphological structures. In summary, in spectroscopic and imaging polarimetry approaches, prominent changes in optical properties of the examined soft biological tissues were discriminated over time. The obtained results are promising in the development of a novel non-destructive tool for monitoring biological tissues for application in biomedical applications and the food industry. The Stokes polarimetry method can provide a comparative analysis of different polarimetric techniques and prove the diagnostic potential of Stokes correlometry of pathological changes in the orientation phase structure of biological tissues

Possibilities of holographic techniques in laser scanning microscopy

Holographic scanning microscopy-novel technique both in laser scanning microscopy and digital holographic microscopy allow multimodal approach to cell and tissue investigation in biomedical applications promising new advantages (quantitative phase imaging, superresolution, computerized tomography), but regular reconstruction leads to incorrectness. Analysis of light propagation through the schematics allows to offer reconstruction procedures depending on recording conditions

Hyperspectral system for Imaging of skin chromophores and blood oxygenation

We developed a compact, fast, hand-held hyperspectral imaging system for 2D neural network-based visualization of skin chromophores and blood oxygenation. Here, we present results of the system tests on healthy volunteers

Monte Carlo investigation of the effect of blood volume and oxygen saturation on optical path in reflectance pulse oximetry

Despite the clinical importance of pulse oximetry, the precise nature of the interaction of light with tissue, which underlies the technique, is not yet fully understood. The limitations of the method with regard toits accuracy inconditions of compromised perfusion and/or low blood oxygen saturations are well documented but have only partly been resolved. Results from a static monolayer Monte Carlo modelof optical path and reflectance attwo wavelengths most commonly usedinpulse-oximetry (660 and 940 nm) through skin tissue, containing different volume fractions of blood witharange of oxygen saturations, are presented. Results exhibited differences in mean optical path (MOP) between the two wavelengths, with differences generally increasing with increasing tissue oxygen saturation and decreasing blood volume.As anexample, inatypical sensor configuration, the MOP of red light traveling through skin containing 7.5% blood volume fraction with mean oxygen saturationof60% was 58% higher than that for infrared. The results presented should contribute to further understandingofthe effectofphysiological conditions suchasanemia, ischemia and hypoxemia on the accuracy of pulse oximetry readings

Multiple scattering of light in optical diagnostics of dense sprays and other complex turbid media

Sprays and other industrially relevant turbid media can be quantitatively and qualitatively characterized using modern optical diagnostics. However, current laser based techniques generate errors in the dense region of sprays due to the multiple scattering of laser radiation e ected by the surrounding cloud of droplets. In most industrial sprays, the scattering of light occurs within the so-called intermediate scattering regime where the average number of scattering events is too great for single scattering to be assumed, but too few for the di usion approximation to be applied. An understanding and adequate prediction of the radiative transfer in this scattering regime is a challenging and non-trivial task that can significantly improve the accuracy and e ciency of optical measurements. A novel technique has been developed for the modelling of optical radiation propagation in inhomogeneous polydisperse scattering media such as sprays. The computational model is aimed to provide both predictive and reliable information, and to improve the interpretation of experimental results in spray diagnostics. Results from simulations are verified against the analytical approach and validated against the experiment by the means of homogeneous solutions of suspended polystyrene spheres. The ability of the technique to simulate various detection conditions, to di erentiate scattering orders and to generate real images of light intensity distributions with high spatial resolution is demonstrated. The model is used for the real case of planar Mie imaging through a typical hollow cone water spray. Versatile usage of this model is exemplified with its applications to image transfer through turbid media, correction of experimental Beer-Lambert measurements, the study of light scattering by single particles in the farfield region, and to simulate the propagation of ultra-short laser pulses within complex scattering media. The last application is fundamental for the development and testing of future optical spray diagnostics; particularly for those based on time-gating detection such as ballistic imaging.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Biophotonics methods for functional monitoring of complications of diabetes mellitus

The prevalence of diabetes complications is a significant public health problem with a considerable economic cost. Thus, the timely diagnosis of complications and prevention of their development will contribute to increasing the length and quality of patient life, and reducing the economic costs of their treatment. This article aims to review the current state-of-the-art biophotonics technologies used to identify the complications of diabetes mellitus and assess the quality of their treatment. Additionally, these technologies assess the structural and functional properties of biological tissues, and they include capillaroscopy, laser Doppler flowmetry and hyperspectral imaging, laser speckle contrast imaging, diffuse reflectance spectroscopy and imaging, fluorescence spectroscopy and imaging, optical coherence tomography, optoacoustic imaging and confocal microscopy. Recent advances in the field of optical noninvasive diagnosis suggest a wider introduction of biophotonics technologies into clinical practice and, in particular, in diabetes care units

Towards enhanced optical sensor performance:SEIRA and SERS with plasmonic nanostars

We report the preparation and characterization of plasmonic chip-based systems comprising self-assembled gold nanostars at silicon substrates that enable concomitantly enhanced Raman (surface enhanced Raman spectroscopy; SERS) and mid-infrared (surface enhanced infrared reflection or absorption spectroscopy; SEIRA) spectral signatures. The high-aspect-ratio structure of gold nanostars provides an increased number of hot spots at their surface, which results in an electric field enhancement around the nanomaterial. Gold nanostars were immobilized at a silicon substrate via a thin gold layer, and α-ω-dimercapto polyethylene glycol (SH-PEG-SH) linkers. The Raman and IR spectra of crystal violet (CV) revealed a noticeable enhancement of the analyte vibrational signal intensity in SERS and SEIRA studies resulting from the presence of the nanostars. Enhancement factors of 2.5 × 10 3 and 2.3 × 10 3 were calculated in SERS considering the CV bands at 1374.9 cm -1 and 1181 cm -1 , respectively; for SEIRA, an enhancement factor of 5.36 was achieved considering the CV band at 1585 cm -1

Circular polarization memory in polydisperse scattering media

We investigate the survival of circularly polarized light in random scattering media. The surprising persistence of this form of polarization has a known dependence on the size and refractive index of scattering particles, however a general description regarding polydisperse media is lacking. Through analysis of Mie theory, we present a means of calculating the magnitude of circular polarization memory in complex media, with total generality in the distribution of particle sizes and refractive indices. Quantification of this memory effect enables an alternate pathway toward recovering particle size distribution, based on measurements of diffusing circularly polarized light

Performance and flow dynamics studies of polymeric optofluidic sers sensors

We present a polymer-based optofluidic surface enhanced Raman scattering chip for biomolecule detection, serving as a disposable sensorchoice with cost-effective production. The SERS substrate is fabricated by using industrial roll-to-roll UV-nanoimprinting equipment andintegrated with adhesive-based polymeric microfluidics. The functioning of the SERS detection on-chip is confirmed and the effect of thepolymer lid on the obtainable Raman spectra is analysed. Rhodamine 6G is used as a model analyte to demonstrate continuous flowmeasurements on a planar SERS substrate in a microchannel. The relation between the temporal response of the sensors and sample flowdynamics is studied with varied flow velocities, using SERS and fluorescence detection. The response time of the surface-dependent SERSsignal is longer than the response time of the fluorescence signal of the bulk flow. This observation revealed the effect of convection on thetemporal SERS responses at 25 μl/min to 1000 μl/min flow velocities. The diffusion of analyte molecules from the bulk concentration intothe sensing surface induces about a 40-second lag time in the SERS detection. This lag time, and its rising trend with slower flow velocities, has to be taken into account in future trials of the optofluidic SERS sensor, with active analyte binding on the sensing surface

The influence of local pressure on evaluation parameters of skin blood perfusion and fluorescence

This article presents the results of the study of the pressure applied on optical diagnostic probes as a significant factor affecting the results of measurements. During stepwise increasing and decreasing of local pressure on skin we conducted measurements using the methods of laser Doppler flowmetry and fluorescence spectroscopy. It was found out that pressure on optical probe has sufficient impact on skin microcirculation to affect registered fluorescence intensity. Data obtained in this study are of interest for design and development of diagnostic technologies for wearable devices. This data will also inform further investigation into issues of compensation of blood absorption influence on fluorescence spectrum, allowing increased accuracy and reproducibility of measurements by fluorescence spectroscopy methods in optical diagnosis