Journal of biophotonics最新文献

Here we propose a not pupil-dependent microsaccades tracking technique and a novel detection method. We present a proof of concept for detecting microsaccades using a non-contact laser-based photonic system recording and processing the temporal changes of speckle patterns scattered from an eye sclera. The data, simultaneously recorded by the speckle-based tracker (SBT) and the video-based eye tracker (Eyelink), was analyzed by the frequently used detection method of Engbert and Kliegl (E&K) and by advanced machine learning detection (MLD) techniques. We detected 93% of microsaccades in the SBT data out of microsaccades detected in the Eyelink data with the E&K method. By utilizing MLD, a precision of 86% was achieved. The findings of our study demonstrate a potential improvement in measuring tiny eye movements, such as microsaccades, using speckle-based eye tracking and, thus, an alternative to video-based eye tracking for detecting microsaccades.

Optical properties determine how light interacts with biological tissues. The current methods for measuring these optical properties are influenced by both deep and superficial skin layers. Polarization-based methods have been proposed in order to determine the influence of deep layer scattering. Polarized light allows for the separation of ballistic photons from diffuse ones, enhancing image contrast and resolution while providing additional tissue information. The Q-sensing technique captures co-polarized $\left(I_{\parallel }\right)$ and cross-polarized $\left(I_{\perp }\right)$ signals, making it possible to isolate the superficial scattering. However, the random structure of tissues leads to rapid depolarization of the polarized light. Detecting where the light becomes depolarized aids in sensing abnormalities within the tissues. Hence, this research focuses on identifying where depolarization occurs within the tissue. Tissue-mimicking phantoms, simulating the optical properties of biological tissues, are created to measure depolarization at various thicknesses. Experimental findings are validated with a Monte Carlo simulation, modeling polarized light behavior through the polydisperse tissue (as the tissue scatterers are heterogeneous in size). Additionally, the research demonstrates how polarized light can extract the optical properties of the medium.

The selection of an appropriate vascular anastomosis process has an important impact on the surgical treatment of coronary artery disease. In this paper, a laser-assisted vascular anastomosis process test was carried out based on the response surface experimental method, and the interaction of laser process parameters on the bursting pressure strength and thermal damage of the anastomotic incision was analyzed, and the relationship model between process parameters and anastomotic performance of the vascular incision tissues was established, and the optimal welding process parameters were obtained. The results show that the laser power has a significant effect on the bursting pressure strength of the anastomotic incision; the interaction of laser power and scanning speed has a substantial impact on the thermal damage of the anastomotic incision; and the anastomotic incision has the best comprehensive performance when the laser power is 6.2 W, the scanning speed is 206 mm/s, and the defocus is 2 mm.

Accurate characterization of mechanical properties is crucial in the evaluation of therapeutic effects for problematic skin conditions. A pilot study was carried out using a novel optical coherence elastography (OCE) device, combining mechanical characterization through suction-based deformation and imaging through optical coherence tomography. Using AI-assisted image segmentation and a power-law model, we were able to describe the mechanical behavior, comparing with measurements from the most commonly used commercial instrument (Cutometer) and subjective analyses of stiffness using the Patient and Observer Scar Assessment Scale. Twenty subjects were included with either keloids or hypertrophic scars. Measurements were fast and produced no discomfort. Mechanical and structural (epidermal thickness and rugosity) descriptors in pathologic skin conditions differed significantly from those in control tissue. We showed for the first time, the clinical feasibility of this novel suction-based OCE device in evaluating mechanical and structural properties in pathological skin conditions such as scars.

Functional near-infrared spectroscopy was used to record spontaneous hemodynamic fluctuations form the bilateral temporal lobes in 25 children with autism spectrum disorder (ASD) and 22 typically developing (TD) children. The coupling between oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (Hb) was calculated by Pearson correlation coefficient, showing significant difference between ASD and TD, thus the coupling could be a characteristic feature for ASD. To evaluate the discrimination ability of the feature obtained in different acquisition times, the receiver operating characteristic curve (ROC) was constructed and the area under curve (AUC) was calculated. The results showed AUC > 0.8 when the time duration was longer than 1.5 min, but longer than 4 min, AUC value (~0.87) hardly varied, implying the maximal discrimination ability reached. This study demonstrated the coupling could be one of characteristic features for ASD even acquired in a short measurement time.

Severe joint infections, such as septic arthritis, require rapid diagnostic testing of the synovial fluid aspirated from joints level so that a surgical team can be assembled quickly. We present a diffuse reflectance spectroscopy (DRS) system for noncontact determination of infection. Using a light-tight syringe holder and fiber optic probe, diffusely reflected light from 475 to 655 nm was acquired from 18 patient samples through the wall of a syringe in a noncontact and sterile manner. We determined the reflectance ratios at two different wavelengths-R₄₉₀/R₆₀₀ and R₅₈₀/R₆₀₀ and found statistically significant differences (p < 0.05) in both ratios between the infected and noninfected groups. Critically, the R₄₉₀/R₆₀₀ and R₅₈₀/R₆₀₀ ratios were significantly correlated with clinical biomarkers-the white blood cell (WBC) and red blood cell (RBC) counts, respectively. This study demonstrates the potential of DRS as a rapid diagnostic tool for joint infections.

The elasticity of the limbus is crucial for ocular health, yet it remains inadequately explored. This study employs acoustic radiation force optical coherence elastography (ARF-OCE) to evaluate the biomechanical properties of the limbus under varying intraocular pressures. The method was validated using a heterogeneous phantom and subsequently applied to ex vivo porcine limbus samples. Elastic wave velocity at specific locations within the limbus was calculated, and the corresponding Young's modulus values were obtained. Spatial elasticity distribution maps were generated by correlating Young's modulus values with their respective locations in the two-dimensional structural images. The results indicate that ARF-OCE enhances the understanding of limbus biomechanical behavior and holds potential for diagnosing regional variations caused by ocular diseases.

Objective: The capillary refill test (CR test) is often used in emergency care, and the capillary refill time (CR time) is used to assess a patient's circulatory condition. The objective of this study was to investigate if repeated CR tests affect CR time.

Methods: Thirteen healthy volunteers had repeated CR tests performed on the sternum, forehead, and fingers. The tests were filmed using polarized reflectance spectroscopy and dedicated software for objective quantification of the CR time.

Results: There were no statistical differences between the first CR test in a series and the following. However, there were statistically significant differences in CR time between the different anatomical sites.

Conclusion: Repeated CR tests, separated by a minimum of 2 min, do not affect CR time in healthy volunteers. The site where the test is performed is of importance for CR time.

Objective: To assess the effectiveness of the REFIX technology in the remineralization process of initial caries simulated on bovine enamel. The assessment involved the analysis of backscatter intensity, which was determined from laser speckle images.

Method: Twenty-one bovine teeth were divided into three groups: G1 and G7 were submitted to treatment with the REFIX technology for 1 and 7 days, respectively. The control group was treated with deionized water.

Results: A significant difference in backscatter was found between the carious and sound areas in all groups (p = 0.0038, p < 0.0001, and p = 0.0002 for the control group, G1, and G7, respectively). The intergroup comparison revealed no significant difference among the groups studied.

Conclusion: REFIX technology did not alter the optical properties of the samples of bovine teeth with simulated initial caries lesions after 1 and 7 days of treatment.

This study explores a combined strategy of Raman and reflectance spectroscopy for quantifying liver fat content and fat droplet size, crucial in assessing donor livers. By using Monte Carlo simulations and experimental setups with oil-in-water phantoms, our findings indicate that Raman scattering can solely differentiate between varying fat contents. At the same time, reflectance intensity is influenced by both fat content and oil droplet size, with a more pronounced sensitivity to fat droplet size. This study demonstrates the efficacy of combined Raman and reflectance spectroscopy in assessing liver steatosis and fat droplet size, potentially aiding in assessing donor livers for transplantation.