This PDF file contains the front matter associated with SPIE Proceedings volume 7572, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Over the last decade, noninvasive glucose sensors based on optical polarimetry have been proposed to probe the anterior chamber of the eye. Such sensors would ultimately be used to measure the aqueous humor glucose concentration which is correlated with blood glucose concentration. Although the effect of other chiral components in the eye has been minimized, the time-variant corneal birefringence due to motion artifact is still a limiting factor which needs to be resolved for realization of such a device. Here we present the development of a real-time dual wavelength optical polarimetric system employing a classical three-term feedback controller. Our dual wavelength system utilizes real-time closed-loop feedback based on proportional-integral-derivative (PID) control, which effectively reduced the time taken by the system to stabilize to less than 300 ms while minimizing the effect of motion artifact, which appears as common noise source for both wavelengths. Measurements in the presence of time-variant test cell birefringence demonstrate the sensitivity of the current system to measure glucose within the range of 0-600 mg/dl with a standard error of less than 13 mg/dl using the dual wavelength information.

A potential noninvasive glucose sensing technique was investigated for application towards in vivo glucose monitoring for individuals afflicted with diabetes mellitus. Three dimensional ray tracing simulations using a realistic iris pattern integrated into an advanced human eye model are reported for physiological glucose concentrations ranging between 0 to 500 mg/dL. The anterior chamber of the human eye contains a clear fluid known as the aqueous humor. The optical refractive index of the aqueous humor varies on the order of 1.5x10^-4 for a change in glucose concentration of 100 mg/dL. The simulation data was analyzed with a developed multivariate chemometrics procedure that utilizes iris-based images to form a calibration model. Results from these simulations show considerable potential for use of the developed method in the prediction of glucose. For further demonstration, an in vitro eye model was developed to validate the computer based modeling technique. In these experiments, a realistic iris pattern was placed in an analog eye model in which the glucose concentration within the fluid representing the aqueous humor was varied. A series of high resolution digital images were acquired using an optical imaging system. These images were then used to form an in vitro calibration model utilizing the same multivariate chemometric technique demonstrated in the 3-D optical simulations. In general, the developed method exhibits considerable applicability towards its use as an in vivo platform for the noninvasive monitoring of physiological glucose concentration.

Polarimetric glucose sensing is a promising method for noninvasive estimation of blood glucose concentration. Published methods of polarimetric glucose sensing generally rely on measuring the rotation of light as it traverses the aqueous humor of the eye. In this article, an interferometer is described that can detect polarization changes due to glucose without the use of polarization control or polarization analyzing elements. Without polarizers, this system is sensitive to optical activity, inherent to glucose, but minimally sensitive to linear retardance, inherent to the cornea. The underlying principle of the system was experimentally verified using spectral domain optical coherence tomography. A detection scheme involving amplitude modulation was simulated, demonstrating sensitivity to clinically relevant glucose concentrations and an acceptable error due to time varying linear birefringence of the cornea using Clarke Error Grid Analysis.

We have been developing dermally-implantable microparticle glucose sensors to monitor interstitial glucose levels. For these sensors to be deployed in vivo, a matched opto-electronic system to interrogate implanted sensors has been designed and constructed. The aim of this study is to test the capability of the sensor system, including in vivo sensor performance, hardware efficiency and hardware optimization based on test results. This paper will report the results of dynamic in vitro tests of sensor performance and the results of preliminary experiments of implants in animal models.

We are developing a continuous glucose monitor for subcutaneous long-term implantation. This detector contains a double chamber Fabry-Perot-etalon that measures the differential refractive index (RI) between a reference and a measurement chamber at 850 nm. The etalon chambers have wavelength dependent transmission maxima which dependent linearly on the RI of their contents. An RI difference of ▵n=1.5·10^-6 changes the spectral position of a transmission maximum by 1pm in our measurement. By sweeping the wavelength of a single-mode Vertical-Cavity-Surface-Emitting-Laser (VCSEL) linearly in time and detecting the maximum transmission peaks of the etalon we are able to measure the RI of a liquid. We have demonstrated accuracy of ▵n=±3.5·10^-6 over a ▵n-range of 0 to 1.75·10^-4 and an accuracy of 2% over a ▵nrange of 1.75·10^-4 to 9.8·10^-4. The accuracy is primarily limited by the reference measurement. The RI difference between the etalon chambers is made specific to glucose by the competitive, reversible release of Concanavalin A (ConA) from an immobilized dextran matrix. The matrix and ConA bound to it, is positioned outside the optical detection path. ConA is released from the matrix by reacting with glucose and diffuses into the optical path to change the RI in the etalon. Factors such as temperature affect the RI in measurement and detection chamber equally but do not affect the differential measurement. A typical standard deviation in RI is ±1.4·10^-6 over the range 32°C to 42°C. The detector enables an accurate glucose specific concentration measurement.

We propose an image-producing Fourier spectroscopic technology that enables two-dimensional spectroscopic images to be obtained within the focusing plane alone. This technology incorporates auto-correlational phase-shift interferometry that uses only object light generated by the bright points that optically make up the object. We are currently involved in studies of non-invasive technologies used to measure blood components such as glucose and lipids, which are measured for use in daily living. Previous studies have investigated non-invasive technologies that measure blood glucose levels by utilizing near-infrared light that permeates the skin well. It has been confirmed that subtle changes in the concentration of a glucose solution, a sample used to measure the glucose level, can be measured by analyzing the spectroscopic characteristics of near-infrared light; however, when applied to a biomembrane, technology such as this is incapable of precisely measuring the glucose level because light diffusion within the skin disturbs the measurement. Our proposed technology enables two-dimensional spectroscopy to a limited depth below the skin covered by the measurement. Specifically, our technology concentrates only on the vascular territory near the skin surface, which is only minimally affected by light diffusion, as discussed previously; the spectroscopic characteristics of this territory are obtained and the glucose level can be measured with good sensitivity. In this paper we propose an image-producing Fourier spectroscopy method that is used as the measuring technology in producing a three-dimensional spectroscopic image.

NIR-spectroscopy and Photoplethysmography (PPG) is used for a measurement of blood components. The absorptioncoefficient of blood differs at different wavelengths. This fact is used to calculate the optical absorbability characteristics of blood which is yielding information about blood components like hemoglobin (Hb), carboxyhemoglobin (CoHb) and arterial oxygen saturation (SpO2). The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. Hemoglobin is the main component of red blood cells. The primary function of Hb is the transport of oxygen from the lungs to the tissue and carbon dioxide back to the lungs. The Hb concentration in human blood is an important parameter in evaluating the physiological status of an individual and an essential parameter in every blood count. Currently, invasive methods are used to measure the Hb concentration, whereby blood is taken from the patient and subsequently analyzed. Apart from the discomfort of drawing blood samples, an added disadvantage of this method is the delay between the blood collection and its analysis, which does not allow real time patient monitoring in critical situations. A noninvasive method allows pain free continuous on-line patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.

To measure blood flow rate in ex-vivo circulation, we propose an optical Doppler flowmeter based on the self-mixing effect within a laser diode (SM-LD). Advantages in adopting SM-LD techniques derive from reduced costs, ease of implementation and limited size. Moreover, the provided contactless sensing allows sensor reuse, hence further cost reduction. Preliminary measurements performed on bovine blood are reported, thus demonstrating the applicability of the proposed measurement method.

Fluorescence microscopy has long been a standard tool in laboratory medicine. Implementation of fluorescence microscopy for near-patient diagnostics, however, has been limited due to cost and complexity associated with traditional fluorescence microscopy techniques. There is a particular need for robust, low-cost imaging in high disease burden areas in the developing world, where access to central laboratory facilities and trained staff is limited. Here we describe a point-of-care assay that combines a disposable plastic cartridge with an extremely low cost fluorescence imaging instrument. Based on a novel, multi-mode planar waveguide configuration, the system capitalizes on advances in volume-manufactured consumer electronic components to deliver an imaging system with minimal moving parts and low power requirements. A two-color cell imager is presented, with magnification optimized for enumeration of immunostained human T cells. To demonstrate the system, peripheral blood mononuclear cells were stained with fluorescently labeled anti-human-CD4 and anti-human-CD3 antibodies. Registered images were used to generate fractional CD4+ and CD3+ staining and enumeration results that show excellent correlation with flow cytometry. The cell imager is under development as a very low cost CD4+ T cell counter for HIV disease management in limited resource settings.

An optical multiplexed homogeneous (liquid phase) immunoassay based on FRET from a terbium complex to eight different fluorescent dyes is presented. We achieved highly sensitive parallel detection of four different lung cancer specific tumor markers (CEA, NSE, SCC and CYFRA21-1) within a single assay and show a proof-of-principle for 5- fold multiplexing. The method is well suited for fast and low-cost miniaturized point-of-care testing as well as for highthroughput screening in a broad range of in-vitro diagnostic applications.

A high-accuracy sensor system has been developed that provides near-instantaneous detection of biomarker proteins as indicators of ovarian serous papillary carcinoma. Based upon photonic guided-mode resonance technology, these highresolution sensors employ multiple resonance peaks to rapidly test for relevant proteins in complex biological samples. This label-free sensor approach requires minimal sample processing and has the capability to measure multiple agents simultaneously and in real time. A detection system has been developed and performance characterized. Identification and quantification of protein biomarkers that are up- or downregulated in blood and serum as indicators of ovarian cancer will be presented.

Accurate characterization of the optical properties of erythrocytes is essential for the applications in optical biomedicine, in particular, for diagnosis of blood related diseases. The observed optical properties strongly depend on the erythrocyte's size, hemoglobin composition and orientation relative to the incident light. We explored the effect of orientation on the absorption and scattering properties of erythrocytes suspended in saline using UV-visible spectroscopy and theoretical predictive modeling based on anomalous diffraction approximation. We demonstrate that the orientation of erythrocytes in dilute saline suspensions is not random and produces consistent spectral pattern. Numerical analysis showed that the multi-wavelength absorption and scattering properties of erythrocytes in dilute suspensions can be accurately described with two orientation populations. These orientation populations with respect to the incident light are face-on incidence and edge-on incidence. The variances of the orientation angles for each population are less than 15 degrees and the relative proportions of the two populations strongly depend on the number density of the erythrocytes in suspensions. Further, the identified orientation populations exhibit different sensitivities to the changes in the compositional and morphological properties of erythrocytes. The anomalous diffraction model based on these orientation populations predicts the absorption and scattering properties of erythrocytes with accuracy greater than 99%. Establishment of the optical properties of normal erythrocytes allows for detection of the disease induced changes in the erythrocyte spectral signatures.

In the present study, we employed the laser scanning confocal microscope to image entire blood flow with accurate red blood cell imaging of 0.001 mm spatial resolution. In vitro blood flow of rat with different hematocrit ratios was simulated inside a 100and 300-micron opaque tube. The scanning rate of confocal microscope was 30 fps with 500 x 500 pixels of image. As a result, we can obtain clear images of RBCs to which is enough to be used as tracer particle directly to get the velocity vector field of blood flow by performing particle image velocimetry (PIV) technique non-invasively. Based on the present novel optical application, we can easily indicate the presence of cell depleted layer of blood flow in vitro and its boundaries.

We have used Monte Carlo simulation of autofluorescence in the retina to determine that noninvasive detection of nutritional iron deficiency is possible. Nutritional iron deficiency (which leads to iron deficiency anemia) affects more than 2 billion people worldwide, and there is an urgent need for a simple, noninvasive diagnostic test. Zinc protoporphyrin (ZPP) is a fluorescent compound that accumulates in red blood cells and is used as a biomarker for nutritional iron deficiency. We developed a computational model of the eye, using parameters that were identified either by literature search, or by direct experimental measurement to test the possibility of detecting ZPP non-invasively in retina. By incorporating fluorescence into Steven Jacques' original code for multi-layered tissue, we performed Monte Carlo simulation of fluorescence in the retina and determined that if the beam is not focused on a blood vessel in a neural retina layer or if part of light is hitting the vessel, ZPP fluorescence will be 10-200 times higher than background lipofuscin fluorescence coming from the retinal pigment epithelium (RPE) layer directly below. In addition we found that if the light can be focused entirely onto a blood vessel in the neural retina layer, the fluorescence signal comes only from ZPP. The fluorescence from layers below in this second situation does not contribute to the signal. Therefore, the possibility that a device could potentially be built and detect ZPP fluorescence in retina looks very promising.

The technologies of high sensitivity optical spectroscopy analysis on turbid media play an important part in scientific research and biomedical applications. The optical path in which photons travel inside the turbid media generally brings information of the components of the media. This paper introduces a novel method to study some of the properties of turbid media by measuring and analyzing the differences of optic paths of wavelength modulated laser beams experienced in the media. The operating principle to accomplish detecting media information in specified optical length is theoretical analyzed. The Experiments and measurements on the multiple scattering properties in transparent media (water, and air) and turbid media (simulation tissue fluid) are reported in the paper as well.

Near-infrared (NIR) spectroscopic measurement of blood and tissue chemistry often requires a large set of subject data for training a prediction model. We have previously developed the principal component analysis loading correction (PCALC) method to correct for subject related spectral variations. In this study we tested the concept of developing PCALC factors from simulated spectra. Thirty, two-layer solid phantoms were made with 5 ink concentrations (0.004%- 0.02%), 2 μs' levels, and 3 fat thicknesses. Spectra were collected in reflectance mode and converted to absorbance by referencing to a 99% reflectance standard. Spectra (5733) were simulated using Kienle's two-layer turbid media model encompassing the range of parameters used in the phantoms. PCALC factors were generated from the simulated spectra at one ink concentration. Simulated spectra were corrected with the PCALC factors and a PLS model was developed to predict ink concentration from spectra. The best-matched simulated spectrum was identified for each measured phantom spectrum. These best-matched simulated spectra were corrected with the PCALC factors derived from the simulated spectra set, and they were used in the PLS model to predict ink concentrations. The ink concentrations were predicted with an R²=0.897, and an estimated error (RMSEP) of 0.0037%. This study demonstrated the feasibility of using simulated spectra to correct for inter-subject spectral differences and accurately determine analyte concentrations in turbid media.

We have designed dual lock-in amplifier (LIA) circuits in 0.18 μm CMOS technology for antibody-antigens (IgG) detection using optoelectronics. The purpose of this work is to develop a lock-in amplifier integrated circuit (IC) using the dual phase scheme that detect the phase difference between the input signal and the reference signal although a phase shifter is absent. Our LIA consist of high gain amplifier, signal amplifier, and phase sensitive detection. Amplifier structure is based on two-stage differential operational amplifier (op-amp) with RC Miller compensation technique. By using the RC Miller compensation technique, we obtain 60° the phase margin of the op-amp. Here, the resistor works for increasing the unit gain bandwidth and the capacitor works for increasing the phase margin. The lock-in amplifier consume 8.6 mA from a 1.8 V supply.

The lymphatic system is not well understood and tools to quantify aspects of its behavior are needed. A technique to monitor lymph velocity that can lead to flow, the main determinant of transport, in a near real time manner can be extremely valuable. We recently built a new system that measures lymph velocity, vessel diameter and contractions using optical microscopy digital imaging with a high speed camera (500fps) and a complex processing algorithm. The processing time for a typical data period was significantly reduced to less than 3 minutes in comparison to our previous system in which readings were available 30 minutes after the vessels were imaged. The processing was based on a correlation algorithm in the frequency domain, which, along with new triggering methods, reduced the processing and acquisition time significantly. In addition, the use of a new data filtering technique allowed us to acquire results from recordings that were irresolvable by the previous algorithm due to their high noise level. The algorithm was tested by measuring velocities and diameter changes in rat mesenteric micro-lymphatics. We recorded velocities of 0.25mm/s on average in vessels of diameter ranging from 54um to 140um with phasic contraction strengths of about 6 to 40%. In the future, this system will be used to monitor acute effects that are too fast for previous systems and will also increase the statistical power when dealing with chronic changes. Furthermore, we plan on expanding its functionality to measure the propagation of the contractile activity.

This paper presents the use of spatially resolved oblique-incidence diffuse reflectance spectroscopy for skin cancer diagnosis. Spatio-spectral data from 166 pigmented skin lesions were collected for the wavelength range from 455 to 765 nm. A set of neural network based classifiers separates the pigmented malignant melanomas from the benign and dysplastic subgroups. A total of 110 lesions were used as the training set and 56 lesions were used as the testing set. This classifier performs with an overall 100% sensitivity and 92% specificity for the training set and 100% sensitivity and 88% specificity for the testing set. The second classifier was designed to separate the benign from the dysplastic subgroups. For the second classifier a total of 100 lesions were used as the training set and 51 lesions were used as the testing set. The overall classification rates were 94% and 88% for the training and testing sets respectively.

In this work we developed a novel technique to remove the fluorescence background in the Raman spectrum. This technique permit us to obtain better accuracy in the spectrum peaks, it is based in the wavelets theory, using symlets and biothogonals wavelets, therefore it is adapting with the Raman Spectrum. We use a spectral range from 300 to 1800(cm^-1), 785 nm laser excitation source and Oceans optics spectrometer was used. The experimental samples were people with different kinds of skin, like brown, black and white. We compare the differences between each Raman spectra, which permitted us to identified persons due to accuracy of Raman spectroscopy. This results shows that Raman spectroscopy has greatly precision in this field of biomedical optics.

Adulteration of milk and dairy products has brought serious threats to human health as well as enormous economic losses to the food industry. Considering the diversity of adulterants possibly mixed in milk, such as melamine, urea, tetracycline, sugar/salt and so forth, a rapid, widely available, high-throughput, cost-effective method is needed for detecting each of the components in milk at once. In this paper, a method using Fourier Transform Infrared spectroscopy (FTIR) combined with two-dimensional (2D) correlation spectroscopy is established for the discriminative analysis of adulteration in milk. Firstly, the characteristic peaks of the raw milk are found in the 4000-400 cm-1 region by its original spectra. Secondly, the adulterant samples are respectively detected with the same method to establish a spectral database for subsequent comparison. Then, 2D correlation spectra of the samples are obtained which have high time resolution and can provide information about concentration-dependent intensity changes not readily accessible from one-dimensional spectra. And the characteristic peaks in the synchronous 2D correlation spectra of the suspected samples are compared with those of raw milk. The differences among their synchronous spectra imply that the suspected milk sample must contain some kinds of adulterants. Melamine, urea, tetracycline and glucose adulterants in milk are identified respectively. This nondestructive method can be used for a correct discrimination on whether the milk and dairy products are adulterated with deleterious substances and it provides a new simple and cost-effective alternative to test the components of milk.