This PDF file contains the front matter associated with SPIE Proceedings Volume 6445, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Infrared spectroscopy has been successfully employed in multi-component assays for the study of various biomedical samples. Two areas have found particular interest, i.e. in-vitro analysis in the clinical laboratory and point-of-care applications. With regard to the latter field, in-vivo blood glucose monitoring is an important topic for improving glycemic control in critically ill patients with non-adequate blood glucose regulation, similar to the situation faced for diabetic patients. For such application, a continuously operated mid-infrared spectroscopic system in combination with a subcutaneously implanted microdialysis probe and coupled by micro-fluidics has been developed. Using the dialysis process, the interstitial fluid matrix can be significantly simplified, since high molecular mass compounds such as proteins are separated. However, the micro-dialysis recovery rate is variable over time, so that a simultaneous determination of this parameter was implemented using the losses of an acetate marker from the perfusate across the dialysis membrane. Clinical measurements were carried out on type 1 diabetic subjects, with experiments lasting up to 28 hours. The concentrations of glucose, acetate and other components in the dialysates from interstitial body fluids were investigated. Two different multivariate calibration strategies, i.e. partial least squares (PLS) and classical least squares (CLS) regressions were applied. The results led to excellent correlation of the subcutaneous interstitial concentrations with those of laboratory blood glucose readings. Clarke-Error-Grid evaluations were employed for assessing the clinical applicability of the method.

A minimally invasive biosensor is undergoing development to detect physiological concentrations of glucose within interstitial fluid. The sensor is based on a chemical assay consisting of Alexa Fluor 647 labeled concanavalin A lectin and dendrimer macromolecules functionalized to contain peripheral glucose moieties. The two components form large cross-linked particles that result in loss of fluorescent emission through shielding of interior fluorophores. As glucose is introduced into the assay, it competes with the glycodendrimers for binding to concanavalin A to disrupt the cross-linked complex and produce a reversible change in fluorescence intensity that is dependent on glucose concentration. Chemical analogs of the original glycodendrimer have been created and analyzed with the purpose of creating more stable and consistent dendrimers in order to maximize the response of the assay so that its signal can be better detected through dermal tissue and provide a better understanding of the sensor binding mechanics.

We report on a theoretical/experimental model to predict the depth sensitivity of laser Doppler perfusion imager. Further more we show the quantitative influence of speckles on laser Doppler perfusion imager response to scattering at different depths. The model is based on Monte Carlo simulations and experiments on static and dynamic scattering phantoms made of polystyrene microspehers. The experimental results are in good agreement with our theoretical predictions. The results show that the depth sensitivity of the laser Doppler perfusion imager is influenced by the speckles. The effects are big, especially when a narrow beam is used for measurement. We propose that a correction method should be developed based on speckle size in order to have a reliable blood perfusion information independent of tissue optical properties.

The examination of human microcirculation allows for monitoring important body conditions. To analyze the human microcirculation, the measurement of the blood flow in capillaries is a efficient method. This requires a high spatial resolution in the first instance. The cutaneous capillary microscopy is a noninvasive optical method, which makes the capillary shape visible in the microcirculation area of interest. A convenient area for observation is the nail fold of the fingers. The erythrocyte columns in these capillaries can be distinguished from their surroundings and from the the blood plasma. This paper presents a system, that determines the flow rate of the erythrocytes in the capillary at the nail fold according to the spatial filter principle. This measuring principle represents an interesting and powerful approach for the determination of the blood flow rate in the capillaries. In the practical use, the unavoidable finger movements of the patients inducing problems in the capillary measurements. This problem is solved by implementing a new fast movement correction. To this end the finger movements will computed and therewith the position of the points for measuring the erythrocyte velocity is corrected. This new system detects the path of a capillary and is able to issue velocity values of blood in the capillaries over a long time and with high temporal resolution.

Physiological blood coagulation is an essential biological process. Current tests for plasma coagulation (clotting) need to be performed ex vivo and require fresh blood sampling for every test. A recently published work describes a new, noninvasive, in vivo approach to assess blood coagulation status during mechanical occlusion¹. For this purpose, we have tested this approach and applied a controlled laser beam to blood micro-vessels of the mouse ear during mechanical occlusion. Standard setup for intravital transillumination videomicroscopy and laser based imaging techniques were used for monitoring the blood clotting process. Temporal mechanical occlusion of blood vessels in the observed area was applied to ensure blood flow cessation. Subsequently, laser irradiation was used to induce vascular micro-injury. Changes in the vessel wall, as well as in the pattern of blood flow, predispose the area to vascular thrombosis, according to the paradigm of Virchow's triad. In our experiments, two elements of Virchow's triad were used to induce the process of clotting in vivo, and to assess it optically. We identified several parameters that can serve as markers of the blood clotting process in vivo. These include changes in light absorption in the area of illumination, as well as changes in the pattern of the red blood cells' micro-movement in the vessels where blood flow is completely arrested. Thus, our results indicate that blood coagulation status can be characterized by non-invasive, in vivo methodologies.

Digital holographic microscopy (DHM) is a technique that allows obtaining, from a single recorded hologram, quantitative phase image of living cell with interferometric accuracy. Specifically the optical phase shift induced by the specimen on the transmitted wave front can be regarded as a powerful endogenous contrast agent, depending on both the thickness and the refractive index of the sample. We have recently proposed a new and efficient decoupling procedure allowing to directly obtain separate measurements of the thickness and the integral refractive index of a given living cell. Consequently, it has been possible to accurately measure (with a precision of 0.0003) the mean refractive index and the volume of living erythrocytes. Here, application of this decoupling procedure on erythrocyte allows to measure a refractive index of 1.40 and a mean volume of about 106 μm³.

NIR-spectroscopy and Photoplethysmography (PPG) and is used for a measurement of blood components. The fact that the absorption-coefficients μ_a and scattering-coefficients μ_s for blood differ at difference wavelengths has been exploited and is used for calculation of the optical absorbability characteristics of human blood yielding information on blood components like hemoglobin and oxygen saturation. The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. A newly developed PMD device has been introduced. The non-invasive in-vivo multi-spectral method is based on the radiation of monochromatic light, emitted by laser diodes, through an area of skin on the finger. Deferrals between the proportions of hemoglobin and plasma in the intravasal volume should be detected photo-electrically by signal-analytic evaluation of the signals. The computed nonlinear coefficients are used for the measurement and calculation of the relative hemoglobin concentration change. Results with this photometric method to measure changes in the hemoglobin concentration were demonstrated during measurements with a hemodynamic model and healthy subjects. The PMD is suitable for non-invasive continuous online monitoring of one or more biologic constituent values. The objective of this development is to reduce the dependence on measurement techniques which require that a sample of blood be withdrawn from the patient for in-vitro analysis. Any invasive method used on the patient to obtain blood is accompanied by problems of inconvenience, stress, and discomfort. The patient is also exposed to the normal risks of infection associated with such invasive methods.

A device and process for preventing medical errors due to the improper administration of an intravenously delivered medication includes the spectroscopic analysis of intravenous fluid components. An emission source and detector are placed adjacent to the intravenous tubing of an administration set to generate signals for spectroscopic analysis. The signals are processed to identify the medication and, in certain embodiments of the invention, can determine the medication's concentration. In a preferred embodiment, the emission source, detector, and hardware and software for the spectroscopic analysis are placed in an infusion pump.

Based on the analysis of skin morphological structure, the mechanism of cutaneous fluorescence emission and diffuse reflectance formation, a six-layer skin optical model was developed, allowing the variation of blood content in both the upper blood plexus and the deep blood plexus. Monte Carlo simulation was performed to examine the effect of varying tissue blood contents on skin fluorescence and diffuse reflectance spectra. The results demonstrated that (1) Both fluorescence and reflectance spectrum can reflect changes of blood content in skin tissue; (2) The impact of blood content in the upper blood plexus on skin spectra intensity is far larger than that in the deep blood plexus, though there is far less blood in the upper blood plexus; (3) Fluorescence and reflectance spectrum could be used to detect or analyze changes of blood content in skin tissue, especially for treatment monitoring and for evaluating the severity of skin diseases that involving the blood plexus or blood pathological changes in the upper dermis.

Prediction of blood glucose using interstitial fluid extracted by ultrasound and vacuum is proposed by the paper. Low-frequency ultrasound with 55 KHz is applied for about 30 seconds to enhance the skin permeability to interstitial fluid by disrupting the stratum corneum lipid bilayers and then interstitial fluid is extracted out of skin successfully by 10in.Hg vacuum for 15 minutes. The glucose concentration in the interstitial fluid is measured by an instrument with immobilized enzyme sensor. And then a method of data analysis is set up to prediction the glucose concentration in the blood by the measurement of the glucose concentration in the interstitial fluid. At last, Clarke Error Grid analysis is performed to assess if the prediction accuracy could satisfy the requirements of clinical application. The whole method and experimental system above is set up in the article and the feasibility of this way for blood glucose detecting is primarily validated for clinical application with the requirements of bloodless, painless, continuous glucose monitoring. Additional a prototype of miniature diabetes monitoring device with the technique of surface plasma resonance to measure the glucose concentration in the interstitial fluid is also being developed.

The overall goal for this project is the development and study of a quantitative fluorescence sensor for in vivo detection of β-amyloid (Aβ), the primary protein component of senile plaques in Alzheimer's disease (AD). Toward achieving that goal a Monte Carlo simulation has been developed to model photon propagation through the human head and a phantom model of the human head has been built and tested. In both cases a four layer model that included the skin, skull, fluorescent biosensor, and gray matter was used. A sensitivity study was performed to investigate the influence on the fluorescent output intensity of changes in concentration of the sensor. The results show that the fluorescent output intensity is detectable with a reasonable fluorescent sensor concentration and increases nearly linearly with increases in fluorescent concentration in the sensor. These results imply that the sensor would be detectable through the head using a reasonable optical system. The overall results are being used to aid in the design of the fluorescent sensor and the optical system for early detection of AD.

In the event of diabetes clinicians have advocated that frequent monitoring of a diabetic's blood glucose level is the key to avoid future complications (kidney failure, blindness, amputations, premature death, etc.,) associated with the disease. While the test-strip glucose meters available in current consumer markets allow for frequent monitoring, a more convenient technique that is accurate, painless and sample-free is preferable in a diabetic's daily routine. This paper presents a non-invasive blood glucose measurement technique using diffuse reflectance near infrared (NIR) signals. This technique uses a set of laser diodes, each operating at fixed wavelengths in the first overtone region. The NIR signals from the laser diodes are channeled to the measurement site viz., the nail-bed by means of optical fibers. A series of in vivo experiments have been performed on eight normal human subjects using a standard Oral Glucose Tolerance Test (OGTT) protocol. The reflected NIR signals are inputs to a Partial Least Squares (PLS) algorithm for calibration and future predictions. The calibration models used are developed using in vivo datasets and are unique to a particular individual. The 1218 paired points collected from the eight test subjects plotted on the Clarke Error Grid, revealed that 87.3% of these points fall within the A zone while the remainder, within the B zone, both of which, are clinically accepted. The standard error of prediction was ±13.14mg/dL for the best calibration model. A Bland-Altman analysis of the 1218 paired points yields a 76.3% confidence level for a measurement accuracy of ±20mg/dL. These results demonstrate the initial potential of the technique for non-invasive blood glucose measurements in vivo.

In the area of noninvasive human blood glucose concentration detecting, it has always been a critical task to extract the glucose-specific signal from the highly overlapped and disturbed near-infrared spectrum. In this paper, the methodology of effective glucose-specific signal extraction in complicated non-scattering sample is studied. By analyzing the impact of water displacement upon dissolution of glucose, the relationship between glucose concentration and absorption coefficient of the sample is deduced. Then, the reference wavelength where the absorption coefficient is insensitive to the changes of glucose concentration is put forward theoretically. Accordingly, the validating experiments in aqueous glucose solutions are executed. Both the theoretical and laboratorial results show that the reference wavelength of glucose appears at 1525nm. Based on the reference wavelength, an effective method for extracting the glucose-specific signal in complicated non-scattering samples is proposed and the corresponding validating experiments are constructed with different glucose and albumin concentration. Two different methods, traditional and the novel reference wavelength method are used to extract glucose signal and the corresponding root mean square error of prediction are 19.86mg/dl and 9.87mg/dl respectively. The experiment results indicate that the reference wavelength method can effectively eliminate the influence of various noises on the glucose-specific signal extraction, and thus can remarkably improve the measuring precision in noninvasive near-infrared glucose detecting.

A new method, floating-reference, can efficiently reduce the influence of the physiological background variations on the blood glucose measurement by differentially processing two signals from reference point and measuring point. In this paper, the reference point, where the diffuse reflected light is not sensitive to the variation of glucose concentration, is theoretically proved. Then Monte Carlo simulations are applied to study the radial distribution of the diffuse reflectance at different glucose concentrations for the skin. Moreover, the experiments are constructed to measure the radial distribution of the diffuse reflectance by the intralipid solutions with different glucose concentrations. Both the results from simulation and experiment validate the existence of floating-reference point. By theoretically analyzing the background noises and their disturbing mode on the blood glucose detection, a novel data processing method based on the reference point is proposed to effectively extract the blood glucose information. And it is found from our preliminary experiments with intralipid samples that, this data processing method can reduce the influence of background variation on the extraction of real glucose signal and thus enhance the resolving capability on glucose concentration.

Glucose is one of the most important substances widely contained in organism and food, thus people pay much attention in researching and improving the way for the detection of glucose. Traditional ways, although precise and reliable when in high concentration and large amount of sample, have unconvincing performance in detecting mixture and solution with low concentration and micro-volume. As far as the ideal way is concerned, it should not only specifically detect the glucose and exclude other components in solution, but also meet the need of micro-sample (approximately 5μL) and low concentration. We introduced D-galactose/D-glucose Binding Protein (GGBP) - a kind of protein which has the ability to absorb the glucose specifically, to construct a novel surface plasmon resonance measuring system. By immobilizing GGBP onto the surface of the SPR sensor, we develop a new detecting system for glucose testing in mixed solution. The experimental result indicates that compared with 0.1g/L before immobilization of GGBP, the detecting limit or the resolution of glucose testing rises to 1mg/L after the immobilization, the system succeeds in distinguishing glucose from other components in mixture, which reveals a bright future to apply SPR in the minimally invasive diabetes testing and food quality control.

Laser speckle imaging technique was used to characterize the spatiotemporal changes in cerebral blood flow (CBF) in rat cortex induced by the local ultraprofound hypothermia(0°C) with the duration time of 1 min, 2 min, 5 min, 7 min and 10 min. The experimental results showed significant difference of the spatiotemporal characteristics of changes in CBF between short term and long term of ultraprofound hypothermia. For the short duration of ultraprofound hypothermia (1 min, 2 min and 5 min), the hypothermia cause the CBF decrease firstly, and then the CBF increase rapidly when the temperature is recovered to 37°C, exceeding the baseline level and lasting 10±3 min, finally return to the baseline. This trend of changes in CBF is similar in the regions of artery, vein and parenchyma, but with different amplitude. For the duration time of 7 min, the changes in CBF also exhibit the similar decrease induced by ultraprofound hypothermia and the rapid increase induced by the temperature recovering, however the increase does not show the overshoot, but only reach around 75% of the baseline level. For the duration of 10 min of ultraprofound hypothermia, the CBF does not increase rapidly when the temperature is recovered to 37°C, but remains at the low level of CBF for 12±2 min, and then increases gradually at artery sites, or increases rapidly and then decrease slightly later at the vein and parenchyma sites. Similar as the case in the duration time of 7 min, the final CBF only recovers to about 75% of the baseline level. The experimental results suggest that the CBF can not recover to the baseline after a long duration of ultraprofound hypothermia longer than 7 min.

This study aimed to investigate the variation of propagation patterns of successive cortical spreading depression (CSD) waves induced by K⁺ or pinprick in rat cortex. In the K⁺ induction group, 18 Sprague-Dawley rats under α-chloralose/urethane anesthesia were used to elicit CSD by 1 M KCl solution in the frontal cortex. Optical intrinsic signal imaging (OISI) at an isosbestic point of hemoglobin (550 nm) was applied to examine regional cerebral blood volume (CBV) changes in the parieto-occipital cortex. In 6 of the 18 rats, OISI was performed in conjunction with DC potential recording of the cortex. The results of this group were reported previously. In the pinprick group, 6 rats were used to induce CSD by pinprick with 8 min interval, and the other 6 rats were pricked with 4 min. CBV changes during CSD appeared as repetitive propagation of wave-like hyperemia at a speed of 3.7±0.4 mm/min, which was characterized by a significant negative peak (-14.3±3.2%) in the reflectance signal. Except for the first CSD wave, the following waves don't spread fully in the observed cortex all the time and they might abort in the medial area. Independent on the stimulation of pinprick or K+, a short interval of the current CSD to the last CSD no more than 4 min would induce the current CSD be partially propagated. For the first time, the data reveals the time-varying propagation patterns of CSD waves might be affected by the interval between CSD waves. The results suggest that the propagation patterns of a series of CSD waves are time-varying in different regions of rat cortex, and the variation is related to the interval between CSD waves.

FT-Raman spectroscopy was employed to access the biochemical alterations occurring on the degenerative process of the rotator cuff supraspinatus tendons. The spectral characteristic variations in the 351 spectra of samples of 39 patients were identified with the help of Principal Components Analysis. The main variations occurred in the 840-911; 1022- 1218; 1257; 1270; 1300; 1452; 1663; and 1751 cm^-1 regions corresponding to the vibrational bands of proline, hydroxiproline, lipids, nucleic acids, carbohydrates, collagen, and elastin. These alterations are compatible with the pathology alterations reported on the literature. Scattering plots of PC 4 vs PC 2 and PC 3 vs PC 2 contrasted with histopathological analysis has enabled the spectral classification of the data into normal and degenerated groups of tendons. By depicting empiric lines the estimated sensibility and specificity were 39,6 % and 97,8 %, respectively for PC 4 vs PC 2 and 36,0 % and 100 %, respectively for PC 3 vs PC 2. These results indicate that Raman spectroscopy can be used to probe the general tendon quality and could be applied as co adjuvant element in the usual arthroscopy surgery apparatus to guide the procedure and possibly infer about the probability of rerupture.

Photo-plethysmography (PPG) is frequently used in research on microcirculation of blood. It is a non-invasive procedure and takes minimal time to be carried out. Usually PPG time series are analyzed by conventional linear methods, mainly Fourier analysis. These methods may not be optimal for the investigation of nonlinear effects of the hearth circulation system like vasomotion, autoregulation, thermoregulation, breathing, heartbeat and vessels. The wavelet analysis of the PPG time series is a specific, sensitive nonlinear method for the in vivo identification of hearth circulation patterns and human health status. This nonlinear analysis of PPG signals provides additional information which cannot be detected using conventional approaches. The wavelet analysis has been used to study healthy subjects and to characterize the health status of patients with a functional cutaneous microangiopathy which was associated with diabetic neuropathy. The non-invasive in vivo method is based on the radiation of monochromatic light through an area of skin on the finger. A Photometrical Measurement Device (PMD) has been developed. The PMD is suitable for non-invasive continuous online monitoring of one or more biologic constituent values and blood circulation patterns.

The feasibility of spatial resolved reflectometry (SRR) and time-of-flight (TOF) techniques application at the wavelength of 820 nm for the detection of changes in optical properties of multilayer scattering medium was considered. The model SRR and TOF signals from a 3-layer biotissue phantom mimicking two skin layers and a blood layer between them were obtained by using Monte Carlo method. It was assumed that changes in the glucose level induce changes only in the blood layer and the deeper skin layer. The scattering maps were obtained in order to analyze the trajectories of the photons contributing to the signals. Different characteristics of the TOF signal were analyzed. Relative changes of the signals induced by the glucose level variations were analyzed for different source-detector separations. It was shown that the maximal relative change of the signal for both techniques of about 7% corresponding to the glucose concentration change from 0 to 500 mg/dl takes place for source-detector separations in the range from 0.3 to 0.5 mm depending on the model parameters.

This paper presents a novel method for detecting a change in the refractive index of samples. One of its major applications is sensing molecular interaction in biological samples. In our study a self-mixing interferometer (SMI) was chosen as the instrument for measuring the refractive index in free -space. A GaN blue laser diode was used as a light-emitting source. Compared with traditional interferometric configurations, self-mixing interferometry combined with the laser diode package has the advantage of a compact setup and high sensitivity. Long-term stability issue was first concerned in our research. The results showed that in 15 minutes the movement of the fringe pattern formed by the self-interfered laser beam is 13.6 nm. The measurement of the refractive index was performed by adding a heating element to the external cavity of the SMI. The refractive index of the air in the external cavity was varied by the atmospheric temperature. The change in the refractive index of the air was calculated using both a modified Edlén equation and the recorded self-interfered signals. The results showed that the change in the refractive index observed from the shift in the fringe pattern is compatible with that calculated with the modified Edlén equation, or about 1×10^-6/°C with optical path length of 5 cm. Theoretically, the smallest movement of the fringe pattern that can be detected with our measurement setup is 1.6 nm, corresponding to a 10^-8 change in the refractive index in the external cavity.

Nowadays as cell culture in microchannels becomes increasingly popular, new and convenient ways to closely monitor the cultured cells in the microchannels are essential. With that objective, we managed to merge different technologies, mainly fluorescence based optical sensing, layer-by-layer encapsulation and Poly Dimethyl Siloxane (PDMS) based microfluidics to build a hybrid system which can provide on-site monitoring of the cellular microenvironment within the microchannels. The system is mainly built from two parts: one is the fluorescence quenching based sensing material which changes its fluorescence intensity proportional to the analyte concentration, for example glucose level in the media; the other part of the system is the microfluidic PDMS chip, featuring some nanoliter wells fabricated beneath the microchannels where the cells could be cultured. These nanowells are intended sites for the immobilization of the sensing material followed by the layer-by-layer encapsulation. Some preliminary results show that the system is sensitive in low analyte concentration, while being highly miniaturized, low cost, easy to be customized and with great potential applications in medical diagnostics and environmental monitoring.

Fluorescent microarrays have the ability to detect and monitor multiple analytes simultaneously and noninvasively, following initial placement. This versatility is advantageous for several biological applications including drug discovery, biohazard detection, transplant organ preservation and cell culture monitoring. In this work, poly(ethylene glycol) hydrogel microarrays are described that can be used to measure multiple analytes, including H+ and dissolved oxygen. The array elements are created by filling micro-channels with a hydrogel precursor solution containing analyte specific fluorescent sensors. A photomask is used to create the microarray through UV polymerization of the PEG precursor solution. A compact imaging system composed of a CCD camera, high powered LED, and two optical filters is used to measure the change in fluorescence emission corresponding to analyte concentration. The proposed system was tested in aqueous solution by altering relevant analyte concentrations across their biological ranges.