This PDF file contains the front matter associated with SPIE Proceedings Volume 10024, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Point-of-care testing (POCT) for an infectious diseases is the prerequisite to control of the disease and limitation of its spread. A microfluidic chip for detection and classification of four strains of Ebola virus was developed and evaluated. This assay was based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) and specific primers for Ebola Zaire virus, Ebola Sudan virus, Ebola Tai Forest virus and Ebola Bundibugyo virus were designed. The sensitivity of the microfluidic chip was under 10³ copies per milliliter, as determined by ten repeated tests. This assay is unique in its ability to enable diagnosis of the Ebola infections and simultaneous typing of Ebola virus on a single chip. It offers short reaction time, ease of use and high specificity. These features should enable POCT in remote area during outbreaks of Ebola virus.

In recent years, the in vivo flow cytometry (IVFC) has been a useful technology in detecting and quantifying the circulating cells dynamically in living animals, especially in the research related to the cell tracking and the cancer metastasis. In practice, however, the unstable background signals caused by the experiment animals’ respiratory movement, limb movement and photo-bleaching of tissues’ auto-fluorescence exist in many IVFC data, which could affect the accuracy of cell counting results in the following post-processing procedure, making the IVFC signals less available. Here we developed a signal processing method that could effectively correct the unstable background signals by using methods combining interpolating, fitting, automatic segmenting and wavelet-based denoising. Compared with the previously used non-correction methods, i.e., the “line-gating” method or the automatic threshold method, this method showed a higher accuracy and efficiency in counting cell numbers of IVFC signals, as well as demonstrating a better statistic results in the Pearson’s correlation coefficient R² and the mean-squared error (MSE).

Microwave-induced thermoacoustic (TA) imaging combines the advantages of high imaging contrast due to electromagnetic absorption and high resolution of the ultrasound technology, and it is a potential alternative imaging technique for biomedical applications, particularly for breast tumor detection. The traditional TA system uses circular-scanning (CS) to obtain complete information to reconstruct a two-dimensional image, however, it needs a large operating space for rotation of the transducers and bulk of coupling medium limiting its medical applications. The linear-scanning (LS) system can overcome these problems partially but usually lose some information and cause image distortion. In this paper, in order to overcome above limitations, a TA imaging system with Sample-Cling-Scanning (SCS) model based on a flexible multi-element transducer is presented. It combines the advantages of both CS and LS modes, and overcome their limitations. Meanwhile, an adaptive back projection algorithm is presented to implement this scanning model. The experimental results show that the proposed system combines advantages including shape adaptation, information integrity, and efficient transmission. These advantages make it a preferred system for TA applications, especially in breast tumor detection.

We have developed a multimodality imaging system by optically integrating all-optical photoacoustic microscopy (AOPAM), optical coherence tomography (OCT) and fluorescence microscopy (FLM) to provide complementary information including optical absorption, optical back-scattering and fluorescence contrast of biological tissue. By sharing the same low-coherence Michelson interferometer, AOPAM and OCT could be organically optically combined to obtain the absorption and scattering information of the biological tissues. Also, owing to using the same laser source and objective lens, intrinsically registered photoacoustic and fluorescence signals are obtained to present the radiative and nonradiative transition process of absorption. Simultaneously photoacoustic angiography, tissue structure and fluorescence molecular in vivo images of mouse ear were acquired to demonstrate the capabilities of the optically integrated trimodality imaging system, which can present more information to study tumor angiogenesis, vasculature, anatomical structure and microenvironments in vivo.

The optical coherence tomography will make progress as the next stage toward a spectroscopic analysis technique. The spectroscopic analysis is based on the Beer-Lambert law. The absorption and scattering coefficients even for the dense medium can be measured by the Beer-Lambert law because the OCT can detect only the light keeping the coherency which propagated rectilinearly and retro-reflected from scatters. This study is concerned with the quantitative verification of Beer-Lambert law in the OCT imaging.

In the last two decades, microfluidic technologies have shown the great potential in developing portable and point-of care testing blood cell analysis devices. It is challenging to integrate all free-space detecting components in a single microfluidic platform. In this paper, a microfluidic cytometer with integrated on-chip optical components was demonstrated. To facilitate on-chip detection, the device integrated optical fibers and on-chip microlens with microfluidic channels on one polydimethylsiloxane layer by standard soft photolithography. This compact design increased the sensitivity of the device and also eliminated time-consuming free-space optical alignments. Polystyrene particles, together with red blood cells and platelets, were measured in the microfluidic cytometer by small angle forward scatter. Experimental results indicated that the performance of the microfluidic device was comparable to a conventional cytometer. And it was also demonstrated its ability to detect on-chip optical signals in a highly compact, simple, truly portable and low cost format which was perfect suitable for point-of-care testing clinical hematology diagnostics.

Planning of irradiance distribution (PID) is one of the foremost factors for on-demand treatment of port wine stains (PWS) with photodynamic therapy (PDT). A weighted optimization method for PID was proposed according to the grading of PWS with a three dimensional digital illumination instrument. Firstly, the point clouds of lesions were filtered to remove the error or redundant points, the triangulation was carried out and the lesion was divided into small triangular patches. Secondly, the parameters such as area, normal vector and orthocenter for optimization of each triangular patch were calculated, and the weighted coefficients were determined by the erythema indexes and areas of patches. Then, the optimization initial point was calculated based on the normal vectors and orthocenters to optimize the light direction. In the end, the irradiation can be optimized according to cosine values of irradiance angles and weighted coefficients. Comparing the irradiance distribution before and after optimization, the proposed weighted optimization method can make the irradiance distribution match better with the characteristics of lesions, and has the potential to improve the therapeutic efficacy.

Liver fibrosis is a common pathological process of varied chronic liver diseases including alcoholic hepatitis, virus hepatitis, and so on. Accurate evaluation of liver fibrosis is necessary for effective therapy and a five-stage grading system was developed. Currently, experienced pathologists use stained liver biopsies to assess the degree of liver fibrosis. But it is difficult to obtain highly reproducible results because of huge discrepancy among different observers. Polarization imaging technique has the potential of scoring liver fibrosis since it is capable of probing the structural and optical properties of samples. Considering that the Mueller matrix measurement can provide comprehensive microstructural information of the tissues, in this paper, we apply the Mueller matrix microscope to human liver fibrosis slices in different fibrosis stages. We extract the valid regions and adopt the Mueller matrix polar decomposition (MMPD) and Mueller matrix transformation (MMT) parameters for quantitative analysis. We also use the Monte Carlo simulation to analyze the relationship between the microscopic Mueller matrix parameters and the characteristic structural changes during the fibrosis process. The experimental and Monte Carlo simulated results show good consistency. We get a positive correlation between the parameters and the stage of liver fibrosis. The results presented in this paper indicate that the Mueller matrix microscope can provide additional information for the detections and fibrosis scorings of liver tissues and has great potential in liver fibrosis diagnosis.

Clinical utility of many biomedical optical devices is limited by the lack of effective and traceable calibration methods. Optical phantoms that simulate biological tissues used for optical device calibration have been explored. However, these phantoms can hardly simulate both structural and optical properties of multi-layered biological tissue. To address this limitation, we develop a 3D printing production line that integrates spin coating, light-cured 3D printing and Fused Deposition Modeling (FDM) for freeform fabrication of optical phantoms with mechanical and optical heterogeneities. With the gel wax Polydimethylsiloxane (PDMS), and colorless light-curable ink as matrix materials, titanium dioxide (TiO₂) powder as the scattering ingredient, graphite powder and black carbon as the absorption ingredient, a multilayer phantom with high-precision is fabricated. The absorption and scattering coefficients of each layer are measured by a double integrating sphere system. The results demonstrate that the system has the potential to fabricate reliable tissue-simulating phantoms to calibrate optical imaging devices.

Tissue-simulating phantoms are used to validate and calibrate optical imaging systems and to understand light transport in biological tissue. Light propagation in a strongly turbid medium such as skin tissue experiences multiple scattering and diffuse reflection from the surface. Surface roughness introduces phase shifts and optical path length differences for light which is scattered within the skin tissue and reflected from the surface. In this paper, we study the effect of mismatched surface roughness on optical measurement and subsequent determination of optical properties of skin tissue. A series of phantoms with controlled surface features and optical properties corresponding to normal human skin are fabricated. The fabrication of polydimethylsiloxane (PDMS) phantoms with known surface roughness follows a standard soft lithography process. Surface roughness of skin-simulating phantoms are measured with Bruker stylus profiler. The diffuse reflectance of the phantom is validated by a UV/VIS spectrophotometer. The results show that surface texture and roughness have considerable influence on the optical characteristics of skin. This study suggests that surface roughness should be considered as an important contributing factor for the determination of tissue optical properties.

There is a pressing need for a phantom standard to calibrate medical optical devices. However, 3D printing of tissue-simulating phantom standard is challenged by lacking of appropriate methods to characterize and reproduce surface topography and optical properties accurately. We have developed a structured light imaging system to characterize surface topography and optical properties (absorption coefficient and reduced scattering coefficient) of 3D tissue-simulating phantoms. The system consisted of a hyperspectral light source, a digital light projector (DLP), a CMOS camera, two polarizers, a rotational stage, a translation stage, a motion controller, and a personal computer. Tissue-simulating phantoms with different structural and optical properties were characterized by the proposed imaging system and validated by a standard integrating sphere system. The experimental results showed that the proposed system was able to achieve pixel-level optical properties with a percentage error of less than 11% for absorption coefficient and less than 7% for reduced scattering coefficient for phantoms without surface curvature. In the meanwhile, 3D topographic profile of the phantom can be effectively reconstructed with an accuracy of less than 1% deviation error. Our study demonstrated that the proposed structured light imaging system has the potential to characterize structural profile and optical properties of 3D tissue-simulating phantoms.

This work is a result of an exploration in response to the following observation: though reconstruction methodology of SIM image since its origin is carried out in frequency domain, recent works in this field, specially when it comes to SIM reconstruction using lesser than 9 raw images, have ventured into reconstruction methodologies that operate directly in the spatial domain. This work formulates and demonstrates a frequency domain reconstruction of SIM image using four raw images – one wide-field image and three SIM images. One of the chief feature of the presented reconstruction algorithm is that it employs the standard ‘tools and tricks’ used by the conventional 9-frame SIM reconstruction algorithm. Results indicate that the presented reconstruction algorithm provides high resolution reconstructions successfully as long as the noise level in the raw images is lower than 10%. For higher level of noise, the reconstruction result shows little resolution enhancement.

Gold nanoparticles exhibit unique plasmonic optical properties in visible to near infrared band. Especially the coupling effect existing at the gap between a closely linked particle pair can make the local field strongly enhanced. These properties make gold particles more attractive to be employed as molecular probes in biomedical related fundamental and clinical researches. However in the bio-system exist many large molecules or groups, whose optical signals can strongly depress the gold particles without detectable. In this paper, we proposed a method to extract the targets which are labelled by gold dimer pairs from large scattering background.

Hepatocarcinoma and esophageal squamous cell carcinomas threaten human life badly. It is a current issue to seek the effective natural remedy from plant to treat cancer due to the resistance of the advanced hepatocarcinoma and esophageal carcinoma to chemotherapy. Berberine (Ber), an isoquinoline derivative alkaloid, has a wide range of pharmacological properties and is considered to have anti-hepatocarcinoma and antiesophageal carcinoma effects. However its low oral bioavailability restricts its wide application. In this report, Ber loaded nanostructured lipid carriers (Ber-NLC) was prepared by hot melting and then high pressure homogenization technique. The in vitro anti-hepatocarcinoma and antiesophageal carcinoma effects of Ber-NLC relative to efficacy of bulk Ber were evaluated. The particle size and zeta potential of Ber-NLC were 189.3 ± 3.7 nm and −19.3 ± 1.4 mV, respectively. MTT assay showed that Ber-NLC effectively inhibited the proliferation of human HepG2 and Huh7 and EC9706 cells, and the corresponding IC₅₀ value was 9.1 μg/ml, 4.4 μg/ml, and 6.3 μg/ml (18.3μg/ml, 6.5μg/ml, and 12.4μg/ml μg/ml of bulk Ber solution), respectively. These results suggest that the delivery of Ber-NLC is a promising approach for treating tumors.

Cellular damage induced by free-radicals like reactive oxygen species has been implicated in several diseases. 2, 2-azobis(2-amidino-propane) dihydrochloride(AAPH) generates two potent ROS capable of inducing lipid peroxidation: alkoxy radical(RO-) and peroxy radical (ROO-). These radicals are similar to those that are physiologically active and thus might initiate a cascade of intracellular toxic events leading to oxidation, lipid peroxidation, DNA damage and subsequent cell death. Hence naturally anti-oxidant play a vital role in combating these conditions. In this study, polydatin loaded nanostructured lipid carriers (Pol-NLC) was prepared by hot melting and then high pressure homogenization technique. The effects of Pol-NLC on free radical scavenging and anti-oxidative capacity is investigated. The particle size and zeta potential of Pol-NLC were 113.9 ± 1.1 nm and −16.3 1 ± 0.27 mV, respectively. By free radical scavenging assays, the IC₅₀ value of Pol-NLC were 28.71, 9.83 μg/mL with DPPH, ABTS assay respectively, and 0.143 mg ferrous sulfate/1 mg Pol-NLC with FRAP assay. These results indicated that the antioxidant properties of Pol-NLC hold great potential used as an alternative to more toxic synthetic anti-oxidants as an additive in food, cosmetic and pharmaceutical preparations for the oxidative diseases treatment.

Photodynamic therapy (PDT) is an effective therapeutic modality that uses a light source to activate light-sensitive photosensitizers to treat both oncologic and nononcological indications. Photosensitizers are excited to the long-lived triplet state, and they react with biomolecules via type I or II mechanism resulted in cell death and tumor necrosis. Free radicals and radical ions are formed by electron transfer reactions (type I), which rapidly react with oxygen leading to the production of reactive oxygen species (ROS), including superoxide ions, hydroxyl radicals and hydrogen peroxide. Singlet molecular oxygen is produced in a Type II reaction, in which the excited singlet state of the photosensitizer generated upon photon absorption by the ground-state photosensitizer molecule undergoes intersystem crossing to a long-lived triplet state. In this talk, the fundmental mechanisms and detection techniques for ROS generation in PDT will be introduced. In particular, the quantification of singlet oxygen generation for pre-clinical application will be highlighted, which plays an essential role in the establishment of robust singlet oxygen-mediated PDT dosimetry.

Background: An increasing prevalence of Candida infections has emerged with the wide use of immune-suppressants and antibiotics. Photodynamic inactivation (PDI) as a new approach to treat localized Candida infections is an emerging and promising field nowadays. This study evaluated the efficacy of photodynamic therapy using two new Cationic benzylidene cyclopentanone photosensitizers(P1 and P2) against strains of clinical fluconazole–resistant Candida albicans.

Methods: Suspensions and biofilms of Candida species were incubated with P1 and P2 concentrations (0.25~50 μM) for 30 min followed by 532nm laser irradiation. For planktonic suspensions, viability of cells was assayed by CFU counting. For biofilms, the metabolic activity was evaluated by XTT. Results: In PDI of a planktonic culture of clinical fluconazole–resistant Candida albicans, P2 showed the higher efficacy. After incubation with 25 μM of P2 for 30 min and irradiation with 532nm laser (36 J cm-²), the viability of C. albicans planktonic cells decreased by 3.84 log10. For biofilm cells, a higher light dose of 75 mW cm-² was necessary to achieve 97.71% metabolic activity reduction.

Conclusions: The results of this investigation demonstrated that benzylidene cyclopentanone photosensitizer（P2）is an efficient photosensitizer to kill C. albicans. Moreover, single-species biofilms were less susceptible to PDT than their planktonic counterparts.

Background: With the increasing emergence of multidrug-resistant (MDR) bacterial strains, there is a pressing need for the development of alternative treatment for infections. Antimicrobial blue light (aBL) has provided a simple and effective approach.

Methods: We first investigated the effectiveness of aBL (415 nm) inactivation of USA300 LAClux (a communityacquired Methicillin-resistant Staphylococcus aureus strain) both in the planktonic and biofilm forms. The survival of the bacteria in suspensions was determined by serial dilution and that of the biofilm-embedded bacteria was determined by bioluminescence quantification. Using a mouse model of thermal burn infected with USA300 LAClux, we further assessed the effectiveness of aBL for treating localized infections. Bioluminescence imaging was performed to monitor in real time bacterial viability in vivo.

Results: In vitro study showed that, for the planktonic counterpart of the bacteria or the 24-h-old biofilms, an irradiance of 55 mW/cm² for 60 min resulted in a 4.61 log₁₀ or 2.56 log₁₀ inactivation, respectively. In vivo study using infected mouse burns demonstrated that a 2.56-log₁₀ inactivation was achieved after 100-mW/cm² irradiation for 62 min. Conclusions: aBL is a potential alternative approach for treating Methicillin-resistant Staphylococcus aureus infections.

Polarized light is sensitive to the microstructures of biological tissues and can be used to detect physiological changes. Meanwhile, spectral features of the scattered light can also provide abundant microstructural information of tissues. In this paper, we take the backscattering polarization Mueller matrix images of bovine skeletal muscle tissues during the 24-hour experimental time, and analyze their multispectral behavior using quantitative Mueller matrix parameters. In the processes of rigor mortis and proteolysis of muscle samples, multispectral frequency distribution histograms (FDHs) of the Mueller matrix elements can reveal rich qualitative structural information. In addition, we analyze the temporal variations of the sample using the multispectral Mueller matrix transformation (MMT) parameters. The experimental results indicate that the different stages of rigor mortis and proteolysis for bovine skeletal muscle samples can be judged by these MMT parameters. The results presented in this work show that combining with the multispectral technique, the FDHs and MMT parameters can characterize the microstructural variation features of skeletal muscle tissues. The techniques have the potential to be used as tools for quantitative assessment of meat qualities in food industry.

Most prostate cancers (PCa) are slowly growing, and only the aggressive ones require early diagnosis and effective treatment. The current standard for PCa diagnosis remains histopathology. Nonetheless, for the differentiation between Gleason score 6 (low-risk PCa), which can be left without treatment, and Gleason score 7 (high-risk PCa), which requires active treatment, the inter-observer discordance can be up to 40%. Our previous study reveals that cholesteryl ester (CE) accumulation induced by PI3K/AKT activation underlies human PCa aggressiveness. However, Raman spectromicroscopy used in this study could only provide compositional information of certain lipid droplets (LDs) selected by the observer, which overlooked cell-to-cell variation and hindered translation to accurate automated diagnosis. Here, we demonstrated quantitative mapping of CE level in human prostate tissues using hyperspectral stimulated Raman scattering (SRS) microscopy that renders compositional information for every pixel in the image. Specifically, hundreds of SRS images at Raman shift between 1620-1800 cm^-1 were taken, and multivariate curve resolution algorism was used to retrieve concentration images of acyl C=C bond, sterol C=C bond, and ester C=O bond. Given that the ratio between images of sterol C=C and ester C=O (sterol C=C/C=O) is nonlinearly proportional to CE percentage out of total lipid, we were able to quantitatively map CE level. Our data showed that CE level was significantly greater in high Gleason grade compared to low Gleason grade, and could be a factor that significantly contributed to cancer recurrence. Our study provides an opportunity towards more accurate PCa diagnosis and prediction of aggressiveness.

Spatially resolved diffuse reflectance spectroscopy method has been proved to be more effective than single point spectroscopy method in the experiment to predict the concentration of the Intralipid diluted solutions. However, Intralipid diluted solution is simple, cannot be the representative of turbid liquids. Blood is a natural and meaningful turbid liquid, more complicate. Hemoglobin is the major constituent of the whole blood. And hemoglobin concentration is commonly used in clinical medicine to diagnose many diseases. In this paper, near infrared spatially resolved transmission spectra (NIRSRTS) and Partial Least Square Regression (PLSR) were used to predict the hemoglobin concentration of human blood. The results showed the prediction ability for hemoglobin concentration of the proposed method is better than single point transmission spectroscopy method. This paper demonstrated the feasibility of the spatially resolved diffuse reflectance spectroscopy method for practical liquid composition analysis. This research provided a new thinking of practical turbid liquid composition analysis.

Near infrared (NIR) has prospectively applied in non-invasive blood glucose measurement due to glucose absorption among the 1.0-2.5m spectral bands. However, this significant technology is hard to be developed because of other blood components and low signal-to-noise ratio (SNR). In this work, we presented a non-invasive glucose measurement system using Fourier transform spectrometer which will work in fingertips or other human body tissues. A refrigerated InGaAs detector with high quantum efficiency performing well in the range of 1.0-1.7μm wavelength is used to acquire transmissive radiation. Preliminary experiment investigations were set up to test glucose levels of aqueous solutions with different concentrations. The analytical modeling of the interferogram data is based on arithmetic Fourier transform and supported by the curvilineal characterization. Experimental results show the variation of light intensity among different glucose concentrations and emphasize the obvious absorption of glucose in NIR wave-range. This study confirms the suitability that NIR can be developed in non-invasive glucose measurement.

The unique optical properties such as brightness, non-bleaching, good bio-compatibility make gold particles ideal label candidates for molecular probes. Due to the strongly enhanced field, aggregation of gold nanoparticles finds themselves plenty of applications in bio-imaging. But limited by its small cross-section associated with nanometer sized particle, it is a big challenge to employ it in a single molecular detection. The field enhancement results from the effect of plasmonic coupling between two closely attached gold nanoparticle under the right excitation condition. With the aim to apply the gold dimer probe to find the molecules in our recently established optical detection method, we compared of the amplitude enhancement by the dimer relative to a single particle. The amplitude distribution under a highly focused illumination objective was calculated, whose results suggest that at the optimized excitation condition, the local field can be enhanced ~190 fold. In consequence, experimental detection was carried out. Gold dimers were linked together by the hybridization of two single chain DNAs. Dimer and single particle probes were mixed together in one detection. Overwhelming contrast between these two kinds of probes were clearly exhibited in the experimental detection image. This method can provide a way to a high specific detection in early diagnosis.

Dynamic spectrum (DS) method is one of the noninvasive approaches to measure the concentration of components in human blood based on the application of photoplethysmogram (PPG). One of the targets of the DS method is to predict the hemoglobin concentration in human blood noninvasively. In previous works, the usually used wavelength in the spectrum is 600-1100 nm which is regarded as the analysis “window” in human tissues. Optimum wavelengths for measurements of hemoglobin concentration have not been investigated yet. In order to improve the precision and reliability of hemoglobin measurements, a method for wavelength selection based on two-dimension (2D) correlation spectroscopy has been studied in this paper. By analyzing the 2D correlation spectroscopy which is generated by the DS data from subject with different blood hemoglobin concentrations, the wavelength bands which are sensible to hemoglobin concentrations in DS can be found. We developed calibration models between the DS data and hemoglobin concentration based on data from 57 subjects. The correlation coefficient is 0.68 in the test set of the model using the whole wavelength band (600-1100nm), while in the test set of the model using the selected wavelength band (850- 950nm) the correlation coefficient is 0.87. Results show the feasibility of wavelength selection utilizing 2Dcorrelation spectroscopy.

Biomedical photoacoustic (PA) signal is characterized with extremely low signal to noise ratio which will yield significant artifacts in photoacoustic tomography (PAT) images. Since PA signals acquired by ultrasound transducers are non-linear and non-stationary, traditional data analysis methods such as Fourier and wavelet method cannot give useful information for further research. In this paper, we introduce an adaptive method to improve the quality of PA imaging based on empirical mode decomposition (EMD) and reconstruction. Data acquired by ultrasound transducers are adaptively decomposed into several intrinsic mode functions (IMFs) after a sifting pre-process. Since noise is randomly distributed in different IMFs, depressing IMFs with more noise while enhancing IMFs with less noise can effectively enhance the quality of reconstructed PAT images. However, searching optimal parameters by means of brute force searching algorithms will cost too much time, which prevent this method from practical use. To find parameters within reasonable time, heuristic algorithms, which are designed for finding good solutions more efficiently when traditional methods are too slow, are adopted in our method. Two of the heuristic algorithms, Simulated Annealing Algorithm, a probabilistic method to approximate the global optimal solution, and Artificial Bee Colony Algorithm, an optimization method inspired by the foraging behavior of bee swarm, are selected to search optimal parameters of IMFs in this paper. The effectiveness of our proposed method is proved both on simulated data and PA signals from real biomedical tissue, which might bear the potential for future clinical PA imaging de-noising.

Diffuse reflectance spectroscopy in the near-infrared (NIR) spectral ranges is a widely used technique for nondestructive inspection of biological tissues. The optical properties, such as absorption and scattering coefficients, can be inversely deduced from the measured quantities and then be used to speculate on some related chemical and physical properties of the tissue. Most studies consider biological tissues as homogeneous semi-infinite turbid media or infinitelywide planar layered turbid media. However, the biological tissues have various geometries, and nearly all of them have curved surfaces. The position and direction of the incident light relative to the tissue surface affect the diffuse reflectance. In this work, we study the influence of incident light offset on the measured diffuse reflectance signals based on the Monte Carlo (MC) simulation. The MC method are regarded as golden standard for light propagation in turbid media and can be used without the limitations of complex tissue geometries. A model for diffuse reflectance spectroscopy measurement using optic fiber probe is built. The incident light is assumed to be an infinitely narrow photon beam. The tissue under detection is assumed to be spherical described by its curvature radius. A series of Monte Carlo simulation are carried out with varying incident directions. Simulation results are analyzed and discussed to assess the influence on the measurements for tissues with different curvature radii. This study may aid in achieving more accurate and effective measurement without extensive experiments.

The incidence of cutaneous malignant melanoma, a disease of worldwide distribution and is the deadliest form of skin cancer, has been rapidly increasing over the last few decades. Because advanced cutaneous melanoma is still incurable, early detection is an important step toward a reduction in mortality. Dermoscopy photographs are commonly used in melanoma diagnosis and can capture detailed features of a lesion. A great variability exists in the visual appearance of pigmented skin lesions. Therefore, in order to minimize the diagnostic errors that result from the difficulty and subjectivity of visual interpretation, an automatic detection approach is required. The objectives of this paper were to propose a hybrid method using random forest and Gabor wavelet transformation to accurately differentiate which part belong to lesion area and the other is not in a dermoscopy photographs and analyze segmentation accuracy. A random forest classifier consisting of a set of decision trees was used for classification. Gabor wavelets transformation are the mathematical model of visual cortical cells of mammalian brain and an image can be decomposed into multiple scales and multiple orientations by using it. The Gabor function has been recognized as a very useful tool in texture analysis, due to its optimal localization properties in both spatial and frequency domain. Texture features based on Gabor wavelets transformation are found by the Gabor filtered image. Experiment results indicate the following: (1) the proposed algorithm based on random forest outperformed the-state-of-the-art in pigmented skin lesions detection (2) and the inclusion of Gabor wavelet transformation based texture features improved segmentation accuracy significantly.

In this study, we have demonstrated a wavelength-swept fiber laser based on an acousto-optic tunable filter(AOTF) as a selective element and a semiconductor optical amplifier(SOA) as a gain medium in an internal fiber ring cavity. The light deriving from one port of the SOA goes through an optical isolator, the AOTF, a fiber coupler and a polarized controller successively, then it goes back to the other port of the SOA to form a ring cavity. The laser output is from another port of the fiber coupler. The laser made by this method is mainly used for swept-source optical coherence tomography(SS-OCT). The application of the SOA provides a sufficiently broad range and can ensure an increased axial resolution of SS-OCT. AOTF offers a wide tuning range, high switching speed and stable operation against vibration for the non-mechanical structure. The proposed wavelength-swept fiber laser ensures a high axial resolution of tomographic images and has a stable laser output. We have discussed the influence of the SOA injection current to the tuning range of the laser. In the SOA injection current of 280 mA, a continuous wavelength tuning range from 1295 to 1370 nm centered at a wavelength of 1330nm is obtained at the sweep rate of 1.06 kHz, and the power of the swept source was 1.14 mW. In addition, for quantitative characterization of the wavelength-swept performance with a AOTF, we have theoretically and experimentally analyzed the influence of the following controllable parameters: injection current, output power and sweeping frequency.

Esophageal cancer is one of the most common malignancies of the gastrointestinal cancers and carries poorer prognosis than other gastrointestinal cancers. In general practice, the depth of tumor infiltration in esophageal wall is crucial to establishing appropriate treatment plan which is established by detecting the tumor infiltration depth. Connective tissue is one of the main structures that form the esophageal wall. So, identification of tumor cells infiltrating into connective tissue is helping for detecting the tumor infiltration depth. Our aim is to evaluate whether multiphoton microscopy (MPM) can be used to detect tumor cells infiltrating into connective tissue in the esophageal cancer. MPM is well-suited for real-time detecting morphologic and cellular changes in fresh tissues since many endogenous fluorophores of fresh tissues are excited through two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). In this work, microstructure of tumor cells and connective tissue are first studied. Then, morphological changes of collagen fibers after the infiltration of tumor cells are shown. These results show that MPM has the ability to detect tumor cells infiltrating into connective tissue in the esophageal cancer. In the future, MPM may be a promising imaging technique for detecting tumor cells in esophageal cancer.

Calcifications within brain tumors may be an indicator of a relatively long survival because a long time is required for the formation of calcium deposits, and may present a novel biomarker associated with response and improved outcome of therapy. In this paper, we describe the use of two-photon excitation fluorescent (TPEF) microscopy combined second harmonic generation (SHG) microscopy for high-resolution imaging that can be applied in identification of intratumoral calcifications. Our results demonstrate that the calcification has stronger TPEF signal than the area around it and the emission spectra shows the difference between the two areas clearly. The TPEF image of calcified region corresponds well with the corresponding H&E stained image. In this work, we present that the label-free imaging technique is able to distinguish the calcified mass lesions in intracranial neoplasms reliably.

Ischemic stroke is one of the common neurological diseases, and it is becoming the leading causes of death and permanent disability around the world. Early and accurate identification of the potentially salvageable boundary region of ischemia brain tissues may enable selection of the most appropriate candidates for early stroke therapies. In this work, TPEF microscopy was used to image the microstructures of normal brain tissues, ischemia regions and the boundary region between normal and ischemia brain tissues. The ischemia brain tissues from Sprague-Dawley (SD) rats were subjected to 6 hours of middle cerebral artery occlusion (MCAO). Our study demonstrates that TPEF microscopy has the ability to not only reveal the morphological changes of the neurons but also identify the boundary between normal brain tissue and ischemia region, which correspond well to the hematoxylin and eosin (H and E) stained images. With the development of miniaturized TPEF microscope imaging devices, TPEF microscopy can be developed into an effectively diagnostic and monitoring tool for cerebral ischemia.

Hyaline cartilage is a semitransparent tissue composed of proteoglycan and thicker type II collagen fibers, while fibro cartilage large bundles of type I collagen besides other territorial matrix and chondrocytes. It is reported that the meniscus (fibro cartilage) has a greater capacity to regenerate and close a wound compared to articular cartilage (hyaline cartilage). And fibro cartilage often replaces the type II collagen-rich hyaline following trauma, leading to scar tissue that is composed of rigid type I collagen. The visualization and quantification of the collagen fibrillar meshwork is important for understanding the role of fibril reorganization during the healing process and how different types of cartilage contribute to wound closure. In this study, second harmonic generation (SHG) microscope was applied to image the articular and meniscus cartilage, and textural analysis were developed to quantify the collagen distribution. High-resolution images were achieved based on the SHG signal from collagen within fresh specimens, and detailed observations of tissue morphology and microstructural distribution were obtained without shrinkage or distortion. Textural analysis of SHG images was performed to confirm that collagen in fibrocartilage showed significantly coarser compared to collagen in hyaline cartilage (p < 0.01). Our results show that each type of cartilage has different structural features, which may significantly contribute to pathology when damaged. Our findings demonstrate that SHG microscopy holds potential as a clinically relevant diagnostic tool for imaging degenerative tissues or assessing wound repair following cartilage injury.

As an integral part of the central nervous system, the spinal cord is a communication cable between the body and the brain. It mainly contains neurons, glial cells, nerve fibers and fiber tracts. The recent development of the optical imaging technique allows high-resolution imaging of biological tissues with the great potential for non-invasively looking inside the body. In this work, we evaluate the imaging capacity of multiphoton microscopy (MPM) based on second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) for the cells and extracellular matrix in the spinal cord at molecular level. Rat spinal cord tissues were sectioned and imaged by MPM to demonstrate that MPM is able to show the microstructure including white matter, gray matter, ventral horns, dorsal horns, and axons based on the distinct intrinsic sources in each region of spinal cord. In the high-resolution and high-contrast MPM images, the cell profile can be clearly identified as dark shadows caused by nuclei and encircled by cytoplasm. The nerve fibers in white matter region emitted both SHG and TPEF signals. The multiphoton microscopic imaging technique proves to be a fast and effective tool for label-free imaging spinal cord tissues, based on endogenous signals in biological tissue. It has the potential to extend this optical technique to clinical study, where the rapid and damage-free imaging is needed.

In this work, an economical and high-efficiency method for detection of melamine in milk was developed. The enrichment effect of coffee-ring was combined with the micro-region analysis of confocal Raman spectroscopy, in addition, assisted with chemometric algorithmthe. Consequently, a desired result was obtained that the LOD of melamine in this method was 1 ppm, which was excellent because the sensitivity of conventional Raman detection was generally low. Furthermore, the whole process were processed in an easily available condition with almost no chemical reagents consumption, and the chosen substrates for the formation of coffee-ring were reusable. Thus, the method is environmental friendly and has a great potential application in food safety inspection.

Cell mitosis plays a crucial role in cell life activity, which is one of the important phases in cell division cycle. During the mitosis, the cytoskeleton micro-structure of the cell changed and the biomechanical properties of the cell may vary depending upon different mitosis stages. In this study, the elasticity property of HeLa cells during mitosis was monitored by atomic force microscopy. Also, the actin filaments in different mitosis stages of the cells were observed by confocal imaging. Our results show that the cell in anaphase is stiffer than that in metaphase and telophase. Furthermore, lots of actin filaments gathered in cells’ center area in anaphase, which contributes to the rigidity of the cell in this phase. Our findings demonstrate that the nano-biomechanics of living cells could provide a new index for characterizing cell physiological states.

The cross section is a significant parameter for fluorescence protein and determination of acceptor-to-donor cross section ratio for two-photon excitation in living cells is the vital issue for two-photon excitation FRET quantification. In this study, Hela cells were labeled with FPs that acceptor-to-donor concentration ratio is 1 to 1 and acceptor-to-donor cross section ratio ranged from 700nm to 960nm was obtained by emission spectral unmixing with independent excitation crosstalk correction. The results show that acceptor-to-donor cross section ratio declines with the excitation wavelength from 700nm to 790nm and then increases inversely from 790nm to 960nm. This method can quickly determine the cross section without any additional references, which could provide a powerful and convenient tool for measuring acceptor-to-donor cross section ratio by two-photon excitation in living cells.

Acupuncture can cause a remarkable increase in degranulation of the mast cells, which has attracted the interest of researchers since the 1980s. Surface-enhanced Raman scattering (SERS) could obtain biochemical information with high sensitivity and specificity. In this study, SERS was used to detect the degree of degranulation of mast cells according to different incubate time. Mast cells was incubated with culture medium for 0 h, 12 h and 24 h, then centrifuge the culture medium, decant the supernatant, and discard the mast cell. SERS was performed to obtain the biochemical fingerprinting signatures of the centrifuged medium. The spectra data are then analyzed by spectral peaks attribution and the principal component analysis (PCA). The measured Raman spectra of the two groups were separated well by PCA. It indicated that mast cells had secreted some substances into cultured medium though degranulation did not happen.

Multi-spectral photoacoustic (MSPA) imaging can extract quantitative information of interesting component from morphological photoacoustic image of targets. A probe with an optimal optical absorption can be detected by MSPA imaging with higher sensitivity and specificity. Here we developed a Nano polymers dots (P-dots) for MSPA imaging that has a high photoacoustic conversion efficiency in a broad optical absorbing band (500 nm - 700 nm). In vivo MSPA imaging experiment was successfully performed in mouse model. The relative concentration map of P-dots was exactly obtained from the background of tissues, which demonstrated the potential use of P-dots in the bio-imaging field based on MSPA imaging.

Estrogen plays an important role in the development and progression of breast cancer, and it promotes proliferation, invasion and metastasis of breast cancer cells. In this paper, we investigated the effect of estrogen on the elasticity of breast cancer cells. 17β-estradiol, one of the most active estrogens in the human body was applied to MCF-7 living cells and the elasticity of breast cancer cells was measured by atomic force microscopy. The force spectroscopy was performed on the center of the cell and the Hertz model was used to calculate the elasticity modulus. Furthermore, the confocal fluorescence imaging was taken to observe the effect of 17β-estradiol on the actin distribution in the cells. The results show that the elasticity of the cells decreases rapidly after the addition of 17β-estradiol, which indicates that the cells appear softer for 17β-estradiol’s treatment. From the confocal imaging, it can be observed that the actin filament rearranged for 17β-estradiol’s treatment, which may lead to the alteration of the cell elasticity. Our findings may deepen our understanding on the rapid effect of 17β-estradiol to MCF-7 cells.

Accuracy of photoacoustic signal is the crux on measurement of oxygen saturation in functional photoacoustic imaging, which is influenced by factors such as defocus of laser beam, curve shape of large vessels and nonlinear saturation effect of optical absorption in biological tissues. We apply Monte Carlo model to simulate energy deposition in tissues and obtain photoacoustic signals reaching a simulated focused surface detector to investigate corresponding influence of these factors. We also apply compensation on photoacoustic imaging of in vivo cat cerebral cortex blood vessels, in which signals from different lateral positions of vessels are corrected based on simulation results. And this process on photoacoustic images can improve the smoothness and accuracy of oxygen saturation results.

Blood glucose concentration measurement is essential for the diagnosis and treatment of diabetes. However, conventional glucose measurement methods are invasive and not suitable for real-time monitoring. This study demonstrated a noninvasive blood glucose measurement method using optical coherence tomography to image human lip in vivo. Optical coherence tomography (OCT) is a noninvasive and depth-resolved technique capable of acquiring tissue structure images in real time. Human lip has very thin skin and is full of blood vessels, which is appropriate for noninvasive glucose measurement. To verify the feasibility of OCT for glucose concentration monitoring, two groups of OCT imaging data were obtained from human lips of normal people. In one group, OCT images of lip were acquired from people on an empty stomach. In the other group, the same sites of lip were observed by OCT 2 hours after breakfast. Evident differences were found from two groups of OCT images that correspond to preprandial glucose and 2- hour postprandial glucose, respectively. The relationship between OCT image and blood glucose concentration was investigated. The result indicates that OCT possesses considerable prospects in terms of noninvasive blood glucose measurement.

Heart pumps blood through the blood vessels to provide body with oxygen and nutrients. As the result, the blood flow, volume and oxygenation in arteries has a pulsatile nature. Measuring these pulsatile parameters enables more precise monitoring of oxygen metabolic rate and is thus valuable for researches and clinical applications. Photoacoustic microscopy (PAM) is a proven label-free method for in vivo measuring blood oxygenation at single blood vessel level. However, studies using PAM to observe the pulsatile nature of blood oxygenation in arteries were not reported. In this paper, we use optical-resolution PAM (OR-PAM) technology to study the blood oxygenation dynamics of pulsatile arteries. First, the ability of our OR-PAM system to accurately reflect the change of optical absorption in imaged objects is demonstrated in a phantom study. Then the system is used to image exposed cortical blood vessels of cat. The pulsatile nature of blood volume and oxygenation in arteries is clearly reflected in photoacoustic (PA) signals, whereas it’s not observable in veins. By using a multi-wavelength laser, the dynamics of the blood oxygenation of pulsatile arteries in cardiac cycles can be measured, based on the spectroscopic method.

Microlasers based on high-Q whispering-gallery-mode (WGM) resonances are promising low-threshold laser sources for bio-sensing and imaging applications. In this talk, we demonstrate a cost effective approach to obtain size-controllable polymer microspheres, which can be served as good WGM microcavities. By injecting SU-8 solution into low-refractiveindex UV polymer, self-assembled spherical droplet with smooth surface can be created inside the elastic medium and then solidified by UV exposure. The size of the microspheres can be tuned from several to hundreds of microns. WGM Lasing has been achieved by optically pumping the dye-doped microspheres with ns lasers. Experimental results show that the microsphere lasers have high quality factors and low lasing thresholds. The self-assembled dye-doped polymer microspheres would provide an excellent platform for the micro-laser sources in on-chip biosensing and imaging systems.

Optical coherence tomography (OCT) is a non-invasive imaging technique that provides real-time two- and three-dimensional images of scattering tissues with micrometer resolution. Scattering coefficient is estimated based on the slope of OCT dependent of depth. However, stability of the OCT signal slope is dependent on tissue heterogeneity. Our work is to provide a method of combining post-processing Fourier filtration with automatic identification of fitting range to reduce the effect of tissue heterogeneity on scattering coefficient, and used for noninvasive monitoring of glucose concentration in lip. Axial and lateral resolutions of OCT are 20 μm and 15 μm respectively. OCT images were obtained from lip before breakfast and after breakfast respectively. Results demonstrate that the method improve the stability and the precision of measurement of scattering coefficient of lip. There are obviously different in scattering coefficient of tissue between preprandial glucose and 2-hours postprandial glucose. These pilot studies show that OCT scattering coefficient extraction of lip may be considered as a significant diagnostic marker. OCT has potential to monitor glucose-induced changes in lip in vivo.

In the non-invasive blood components measurement using near infrared spectroscopy, the useful signals caused by the concentration variation in the interested components, such as glucose, hemoglobin, albumin etc., are relative weak. Then the signals may be greatly disturbed by a lot of noises in various ways. We improved the signals by using the optimum path-length for the used wavelength to get a maximum variation of transmitted light intensity when the concentration of a component varies. And after the path-length optimization for every wavelength in 1000-2500 nm, we present the detection limits for the components, including glucose, hemoglobin and albumin, when measuring them in a tissue phantom. The evaluated detection limits could be the best reachable precision level since it assumed the measurement uses a high signal-to-noise ratio (SNR) signal and the optimum path-length. From the results, available wavelengths in 1000-2500 nm for the three component measurements can be screened by comparing their detection limit values with their measurement limit requirements. For other blood components measurement, the evaluation their detection limits could also be designed using the method proposed in this paper. Moreover, we use an equation to estimate the absorbance at the optimum path-length for every wavelength in 1000-2500 nm caused by the three components. It could be an easy way to realize the evaluation because adjusting the sample cell’s size to the precise path-length value for every wavelength is not necessary. This equation could also be referred to other blood components measurement using the optimum path-length for every used wavelength.

Alterations in the elastic fibers have been implicated in lung cancer. However, the label-free, microscopic imaging of elastic fibers in situ remains a major challenge. Here, we present the use of intrinsic two-photon excited fluorescence (TPEF) signal as a novel means for quantification of the elastic fibers in intact fresh human lung tissues. We obtained the TPEF images of elastic fibers from ex vivo the human lung tissues. We found that three features, including the elastic fibers area, the elastic fibers orientation, the elastic fibers structure, provide the quantitative identification of lung cancer and the direct visual cues for cancer versus non-cancer areas. These results suggest that the TPEF signal can be used as the label-free optical biomarkers for rapid clinical lung diagnosis and instant image-guided surgery.

This paper is based on the finite element analysis method for studying effects of large blood vessel on temperature based on photothermal coupling interaction model, and it couples the physical field of optical transmission with the physical field of heat transfer in biological tissue by using COMSOL Multiphysics 4.4 software. The results demonstrate the cooling effect of large blood vessel, which can be potential application for the treatment of liver tumors.

Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) imaging, has become a powerful, important tool for tissue imaging at the molecular level. Recently, MPM is also used to image hematoxylin and eosin (H and E)-stained sections in cancer diagnostics. However, several studies have showed that the MPM images of tissue stained with H and E are significantly different from unstained tissue sections. Our aim was to detect of the multiphoton signals in stained tissue by using MPM. In this paper, MPM was used to image histological sections of esophageal invasive carcinoma tissues stained with H, E, H and E and fresh tissue. To detect of the multiphoton signals in stained tissue, the emission spectroscopic of tissue stained with H, E, H and E were obtained. For comparison, the fresh tissues were also investigated. Our results showed that the tissue stained with H, E, H and E could be detected by their TPEF signals. While the tissue stained with H and fresh tissue could be detected by their TPEF and SHG signals. In this work, we detect of the multiphoton signals in stained tissue. These findings will be useful for choosing suitable staining method so to improve the quality of MPM imaging in the future.

To enhance drug delivery performance of popular drug eluting balloon against re-stenosis after angioplasty, we have an idea regarding to adjacent use of our unique laser driven thermal balloon of which characteristics could realize short term and uniform temperature elevation to modify drug delivery characteristics. We have already reported a delivery enhancement effect using this idea, however, detailed characteristics have not been studied yet. We studied balloon dilatation in terms of vascular circumferential tension on the heating drug delivery performance using porcine carotid artery wall ex vivo. The extracted carotid artery was used and circumferential tension of 0-30 mN/mm² was added. Heating drug delivery was performed on this carotid artery with the heated solution of hydrophobic fluorescent Rhodamine B with 3 μg/ml in concentration at 37 and 70°C. We obtained a defined drug delivery quantity as well as delivery depth by a microscopic fluorescence measurement on a cross section of the drug delivered vessel wall. In the cases of 70°C, we found the drug penetration increase against 3°C case. We predict that the collagen thermal denaturation of the vessel wall may play important role to this penetration. In the case of 3°C, we found the drug concentration on the intimal surface with 7 mN/mm² was increased as 10-30 times as other tension values. We found surface grooves in this case using an electron micrography. Therefore, we think that the drug delivery enhancement might be related to the groove formations of the vessel wall.

In the non-invasive blood glucose concentration (BGC) sensing, the measurement based on near infrared spectroscopy has been a promising technology since it had acquired dozens of satisfactory results in short-term glucose monitoring tests. However, it’s still necessary to improve the measurement precision because it has challenges of the reduced precision in a long-term test when a lot of variables in the test would exist. Considering the requirement of multivariable analysis, the signals of diffuse reflectance spectra should include enough absorption information from glucose. However, the sensitivity of diffuse light intensity to the absorption variation at different source detector separations (SDSs) could be different. We present an analysis method using Monte-Carlo (MC) simulation and the diffuse equation for reasonably selecting proper SDS to get a satisfactory glucose measurement precision when there are multivariable disturbances. In the case of measuring glucose in a tissue phantom using the waveband of 1000-1340 nm, we show the SDS optimization result by using this analysis method. The experiment was designed to measure the diffuse reflectance spectra at 0.1-3.0 mm with the step of 0.1 mm, and the phantom solutions with different glucose concentrations and hemoglobin concentrations are tested. The glucose prediction precision was evaluated using the root mean squared error of prediction (RMSEP) for the all SDSs of 0.1-3.0 mm, and the SDSs with the lower RMSEP were selected for use. Moreover, the selected SDSs in the experiment shows a similar conclusion from the MC simulation. This work could be referenced to the in vivo BGC measurement.

Multiple diseases such as breast tumor poses a great threat to women's health and life, while the traditional detection method is complex, costly and unsuitable for frequently self-examination, therefore, an inexpensive, convenient and efficient method for tumor self-inspection is needed urgently, and lesion localization is an important step. This paper proposes an self-examination method for positioning of a lesion.

The method adopts transillumination to acquire the hyperspectral images and to assess the spatial information of lesion. Firstly, multi-wavelength sources are modulated with frequency division, which is advantageous to separate images of different wavelength, meanwhile, the source serves as fill light to each other to improve the sensitivity in the low-lightlevel imaging. Secondly, the signal-to-noise ratio of transmitted images after demodulation are improved by frame accumulation technology. Next, gray distributions of transmitted images are analyzed. The gray-level differences is constituted by the actual transmitted images and fitting transmitted images of tissue without lesion, which is to rule out individual differences. Due to scattering effect, there will be transition zones between tissue and lesion, and the zone changes with wavelength change, which will help to identify the structure details of lesion. Finally, image segmentation is adopted to extract the lesion and the transition zones, and the spatial features of lesion are confirmed according to the transition zones and the differences of transmitted light intensity distributions. Experiment using flat-shaped tissue as an example shows that the proposed method can extract the space information of lesion.

Conventionally endoscopic OCT images are reconstructed by uniform sampling in both axial and transverse direction of the image. To shorten the scanning time and reduce the acquisition data, we propose to sparsely sample the axial scans and use compressive sensing (CS) to reconstruct the full endoscopic OCT image with randomly chosen axial scans that are much less than conventional Nyquist criteria requirement. And we study the ratio of sparse sampling numerically and experimentally that are required to reconstruct acceptable OCT images. We demonstrate that the OCT image acquisition time can be significantly reduced because of much less acquired data.

The measurement accuracy of non-invasive blood glucose concentration (BGC) sensing with near-infrared spectroscopy is easily affected by the temperature variation in tissue because it would induce an unacceptable spectrum variation and the consequent prediction deviation. We use a multivariable correction method based on external parameter orthogonalization (EPO) to calibrate the spectral data recorded at different temperature values to reduce the spectral variation. The tested medium is a kind of tissue phantom, the Intralipid aqueous solution. The calibration uses a projection matrix to get the orthogonal spectral space to the variable of external parameter, i.e. temperature, and then the useful spectral information relative to glucose concentration has been reserved. Even more, training the projection matrix can be separated to building the calibration matrix for the prediction of glucose concentration as it only uses the representative samples’ data with temperature variation. The method presents a lower complexity than modeling a robust prediction matrix, which can be built from comprehensive spectral data involved the all variables both of BGC and temperature. In our test, the calibrated spectra with the same glucose concentration but different temperature values show a significantly improved repeatability. And then the glucose concentration prediction results show a lower root mean squared error of prediction (RMSEP) than that using the robust calibration model, which has considered the two variables. We also discuss the rationality of the representative samples chosen by EPO. This research may be referenced to the temperature calibration for in vivo BGC sensing.

Position-based reference measurement method is taken as one of the most promising method in non-invasive measurement of blood glucose based on spectroscopic methodology. Selecting an appropriate source-detector separation as the reference position is important for deducting the influence of background change and reducing the loss of useful signals. Our group proposed a special source-detector separation named floating-reference position where the signal contains only background change, that is to say, the signal at this source-detector separation is uncorrelated with glucose concentration. The existence of floating-reference position has been verified in a three layer skin by Monte Carlo simulation and in the in vitro experiment. But it is difficult to verify the existence of floating-reference position on the human body because the interference is more complex during in vivo experiment. Aiming at this situation, this paper studies the determination of the best reference position on human body by collecting signals at several source-detector separations on the palm and measuring the true blood glucose levels during oral glucose tolerance test (OGTT) experiments of 3 volunteers. Partial least square (PLS) calibration model is established between the signals at every source-detector separation and its corresponding blood glucose levels. The results shows that the correlation coefficient (R) between 1.32 mm to 1.88 mm is lowest and they can be used as reference for background correction. The signal of this special position is important for improving the accuracy of near-infrared non-invasive blood glucose measurement.

Optical resolution photoacoustic microscopy (ORPAM) is currently one of the fastest evolving photoacoustic imaging modalities. It has a comparable spatial resolution to pure optical microscopic techniques such as epifluorescence microscopy, confocal microscopy, and two-photon microscopy, but also owns a deeper penetration depth. In this paper, we report a rotary-scanning (RS)-ORPAM that utilizes a galvanometer scanner integrated with objective to achieve rotary laser scanning. A 15 MHz cylindrically focused ultrasonic transducer is mounted onto a motorized rotation stage to follow optical scanning traces synchronously. To minimize the loss of signal to noise ratio, the acoustic focus is precisely adjusted to reach confocal with optical focus. Black tapes and carbon fibers are firstly imaged to evaluate the performance of the system, and then in vivo imaging of vasculature networks inside the ears and brains of mice is demonstrated using this system.

The blood hemoglobin concentration’s (BHC) measurement using Photoplethysmography (PPG), which gets blood absorption to near infrared light from the instantaneous pulse of transmitted light intensity, has not been applied to the clinical use due to the non-enough precision. The main challenge might be caused of the non-enough stable pulse signal when it’s very weak and it often varies in different human bodies or in the same body with different physiological states. We evaluated the detection limit of BHC using PPG as the measurement precision level, which can be considered as a best precision result because we got the relative stable subject’s pulse signals recorded by using a spectrometer with high signal-to-noise ratio (SNR) level, which is about 30000:1 in short term. Moreover, we optimized the used pathlength using the theory based on optimum pathlength to get a better sensitivity to the absorption variation in blood. The best detection limit was evaluated as about 1 g/L for BHC, and the best SNR of pulse for in vivo measurement was about 2000:1 at 1130 and 1250 nm. Meanwhile, we conclude that the SNR of pulse signal should be better than 400:1 when the required detection limit is set to 5 g/L. Our result would be a good reference to the BHC measurement to get a desired BHC measurement precision of real application.