Background: Fetal well-being is determined in large part by how well the placenta is able to supply oxygen and nutrients, but current technology is unable to directly measure how well a placenta functions. Near-infrared spectroscopy (NIRS) utilizes optical methods to measure tissue oxygenation. This pilot project evaluated the feasibility of NIRS for fetal monitoring through the maternal abdominal wall using a sheep model. Methods: A miniature wireless 2-wavelength NIRS device was placed on the abdominal skin over the placenta of a pregnant ewe whose fetus had been chronically catheterized to allow arterial sampling for measurement of arterial oxygen saturation. The NIRS device has 3-paired light emitting diodes and a single photodiode detector; allowing measurement of an index of tissue oxygen saturation (TSI%). Fetal limb TSI% values were compared before and during fetal breathing movements. Correlation was made during these events between arterial values and placental TSI% monitored continuously in real time. Results: Serial measurements were obtained in a single experiment. The correlation between transcutaneous NIRS derived TSI% and direct arterial oxygen saturation was very high (R2=0.86). Measures of fetal limb TSI% were declined after episodes of fetal breathing (P<0.005). Conclusions: This correlation suggests that NIRS is sensitive enough to detect changes in fetal tissue oxygenation noninvasively through the maternal abdominal wall in real-time in a sheep model. NIRS data confirmed that fetal breathing movements decrease arterial oxygen saturation in fetal lambs. If validated by further study this optical methodology could be applied as means of monitoring fetal wellbeing in humans.

Non-invasive diode laser spectroscopy was, for the first time, used to assess gas content in the intestines and the lungs of a new-born, 4 kg, baby. Two gases, water vapor and oxygen, were studied with two low-power tunable diode lasers, illuminating the surface skin tissue and detecting the diffusely emerging light a few centimeters away. The light, having penetrated into the tissue, had experienced absorption by gas located in the lungs and in the intestines. Very distinct water vapor signals were obtained from the intestines while imprint from oxygen was lacking, as expected. Detectable, but minor, signals of water vapor were also obtained from the lungs, illuminating the armpit area and detecting below the collar bone. Water vapor signals were seen but again oxygen signals were lacking, now due to the difficulties of penetration of the oxygen probing light into the lungs of this full-term baby. Ultra-sound images were obtained both from the lungs and from the stomach of the baby. Based on dimensions and our experimental findings, we conclude, that for early pre-term babies, also oxygen should be detectable in the lungs, in addition to intestine and lung detection of water vapor. The present paper focuses on the studies of the intestines while the lung studies will be covered in a forthcoming paper.

Between the years 1999 and 2008, on average 2,052 people died per year on the waiting list for liver transplants. Monitoring perfusion and oxygenation in transplanted organs in the 7 to 14 days period post-transplant can enhance graft and patient survival rates, and resultantly increase the availability of organs. In this work, we present in vitro results using a unique liver phantom that support the ability of our sensor to detect perfusion changes in the portal vein at low levels (50 mL/min . 4.5% of normal level). Our sensor measures diffuse reflection from three wavelengths (735, 805 and 940 nm) around the hemoglobin isobestic point (805 nm) to determine perfusion and oxygenation separately. To assess the sensitivity of our sensor to flow changes in the low range, we used two peristaltic pumps to pump a dye solution mimicking the optical properties of oxygenated blood, at various rates, through a PDMS based phantom mimicking the optical properties of liver tissue. The collected pulsatile signal increased by 120% (2.2X) for every 100 mL/min flow rise for all three wavelengths in the range 50 to 500 mL/min. In addition, we used different dye mixtures to mimic oxygenation changes at constant perfusion/flow levels. The optical properties of the dye mixtures mimic oxygen saturations ranging between 0 and 100%. The sensor was shown to be sensitive to changes in oxygen saturations above 50%.

We measured the oxygen saturation of skin at various ages using our previously proposed method that can rapidly simulate skin spectral reflectance with high accuracy. Oxygen saturation is commonly measured by a pulse oximeter to evaluate oxygen delivery for monitoring the functions of heart and lungs at a specific time. On the other hand, oxygen saturation of skin is expected to assess peripheral conditions. Our previously proposed method, the optical path-length matrix method (OPLM), is based on a Monte Carlo for multi-layered media (MCML), but can simulate skin spectral reflectance 27,000 times faster than MCML. In this study, we implemented an iterative simulation of OPLM with a nonlinear optimization technique such that this method can also be used for estimating hemoglobin concentration and oxygen saturation from the measured skin spectral reflectance. In the experiments, the skin reflectance spectra of 72 outpatients aged between 20 and 86 years were measured by a spectrophotometer. Three points were measured for each subject: the forearm, the thenar eminence, and the intermediate phalanx. The result showed that the oxygen saturation of skin remained constant at each point as the age varied.

We have developed a snapshot optical imaging system capable of taking multiple images simultaneously and sending them to a CCD detector. Using an innovative lens array design, the beam obtained from the fundus camera is segmented into several different images passed through several different bandpass filters. Each bandpass filter defines a unique spectral region of imaging. The images are taken simultaneously into a large silicone chip with a dynamic range of 16 bits (highly sensitive) and are integrated with a single optical connection to a digital fundus camera. Our algorithm maps blood oxygen saturation of the retina using several wavelengths. These wavelengths are capable of approximating the whole hemoglobin spectrum and have been found from a previously developed hyperspectral algorithm. They include four isosbestic points (522, 548, 569, and 586 nm) and three oxygen-sensitive points (542, 560, and 586 nm) where the difference between fully oxygenated and deoxygenated blood is at a maximum. Using MatLab code, color maps of oxygen saturation are produced. The average value taken from all vein areas was 60.53%, assuming that the artery oxygen saturation value is 98%. Oxygen saturation of the tissue was 75.78%. Oxygen saturations of the temporal/inferior/nasal veins ranged from 61.86% to 63.37%; the superior vein was significantly lower (54.19%). Tissue oxygen saturations in different quadrants of the eye ranged from 74.17% to 76.74%. Our algorithm has been developed for measuring oxygen saturation of the retina clinically. This was done for one subject only; further work can extend the measurements to different pigments.

Hydrogen peroxide (H₂O₂) is known to play a multifaceted role in cell physiology mechanisms involving oxidative stress and intracellular signal transduction. Therefore, the development of analytical tools providing information on the dynamics of H₂O₂ generation remains of utmost importance to achieve further insight in the complex physiological processes of living cells and their response to environmental stress. In the present work we developed a novel optic biosensor that provides continuous real-time quantification of the dynamics of the hydrogen peroxide release from cells under oxidative stress conditions. The biosensor is based on the ultra-sensitive dark field optical detection of cytochrome c (cyt c) that exhibits a narrow absorption peaks in its reduced state (Fe(II)) at λ = 550 nm. In the presence of H₂O₂ the ferrous heme group Fe(II) is oxidised into Fe(III) providing the spectroscopic information exploited in this approach. Extremely low limit-of-detection for H₂O₂ down to the subnanomolar range is achieved by combining scattering substrates (eg. polystyrene beads) able to shelter cyt c and an inverted microscope in dark field configuration. The developed biosensor was able to perform real-time detection of H₂O₂ extracellular release from human promyelocytic leukemia cells (HL-60) exposed to lipopolysaccaride (LPS) that elicits strong immune-response. This biosensing tool is currently being implemented to the real-time detection of superoxide anion (O₂.^-) and offers the possibility to extend to further oxidative stress biomarkers such as glutathione. More generally, multianalyte and dynamic informations might bring new insights to understand complex cellular metabolisms involved in oxidative-stress-related diseases and cytotoxic responses.

All dietary lipids are transported to venous circulation through the lymphatic system, yet the underlying mechanisms that regulate this process remain unclear. Understanding how the lymphatics functionally respond to changes in lipid load is important in the diagnosis and treatment of lipid and lymphatic related diseases such as obesity, hypercholesterolemia, and lymphedema. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. A custom-built optical set-up provides us with the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. This is achieved by dividing the light path into two optical bands. Utilizing high-speed and back-illuminated CCD cameras and post-acquisition image processing algorithms, we have the potential quantify correlations between vessel contraction, lymph flow and lipid concentration of mesenteric lymphatic vessels in situ. Local flow velocity is measured through lymphocyte tracking, vessel contraction through measurements of the vessel walls and lipid uptake through fluorescence intensity tracking of a fluorescent long chain fatty acid analogue, Bodipy FL C₁₆. This system will prove to be an invaluable tool for both scientists studying lymphatic function in health and disease, and those investigating strategies for targeting the lymphatic system with orally delivered drugs.

Background - Near-infrared (NIR) imaging of lymphatic drainage of injected indocyanine green (ICG) has emerged as a new technology for clinical imaging of lymphatic architecture and quantification of vessel function, offering better spatial and temporal resolution than competing imaging modalities. While NIR lymphatic imaging has begun to be reported in the literature, the technology is still in its infancy and its imaging capabilities have yet to be quantitatively characterized. The objective of this study, therefore, was to characterize the parameters of NIR lymphatic imaging to quantify its capabilities as a diagnostic tool for evaluating lymphatic disease. Methods - An NIR imaging system was developed using a laser diode for excitation, ICG as a fluorescent agent, and a CCD camera to detect emission. A tissue phantom with mock lymphatic vessels of known depths and diameters was used as an alternative to in vivo lymphatic vessels due to the greater degree of control with the phantom. Results and Conclusions - When dissolved in an albumin physiological salt solution (APSS) to mimic interstitial fluid, ICG experiences shifts in the excitation/emission wavelengths such that it is maximally excited at 805nm and produces peak fluorescence at 840nm. Premixing ICG with albumin induces greater fluorescence intensity, with the ideal concentration being: 900μM (60g/L) albumin and 193.5μM (150μg/mL) ICG. ICG fluorescence can be detected as deep as 6mm, but spatial resolution deteriorates severely below 3mm, thus skewing vessel geometry measurements. ICG packet travel, a common measure of lymphatic transport, can be detected as deep as 5mm.

An optical particle detection and analysis method is presented. This method combines the capillary microfluidics, integrated optics and novel image acquisition and analysis algorithms to form the basis of a portable or handheld cytometer instrument. Experimental results provided shows the testing results are closely matched with conventional flow cytometer data.

Visceral leishmaniasis (L.donovani) is a protozoan infection that attacks mononuclear phagocytes and causes the liver and spleen damage that can cause death. The investigation presented is a proof of concept development applying a plasmonic diagnostic platform with simple microfluidic sample delivery and optical readout. An immune-assay method is applied to the quantification of A2 protein, a highly immunogenic biomarker for the pathogen. Quantification of A2 was performed in the ng/ml range, analysis by ELISA suggested that a limit of 0.1ng/ml of A2 is approximate to 1 pathogen per ml and the sensing system shows the potential to deliver a similar level of quantification. Significant reduction in assay complexity as further enzyme linked enhancement is not required when applying a plasmonic methodology to an immunoassay. The basic instrumentation required for a portable device and potential dual optical readout where both plasmonic and photoluminescent response are assessed and investigated including consideration of the application of the device to testing where non-literate communication of results is considered and issues of performance are addressed.

There are three stages to a complete UTI diagnosis: (1) identification of a urine sample as positive/negative for an infection, (2) identification of the responsible bacterium, (3) antibiogram to determine the antibiotic to which the bacteria are most sensitive to. Using conventional methods, all three stages require bacterial cultures in order to provide results. This long delay in diagnosis causes a rise in ineffective treatments, chronic infections, health care costs and antibiotic resistance. In this work, SERS is used to identify a sample as positive/negative for a UTI as well as to obtain an antibiogram against different antibiotics. SERS spectra of serial dilutions of E. coli bacteria mixed with silver nanoparticles, showed a linear correlation between spectral intensity and concentration. For antibiotic sensitivity testing, SERS spectra of three species of gram negative bacteria were collected four hours after exposure to the antibiotics ciprofloxacin and amoxicillin. Spectral analysis revealed clear separation between bacterial samples exposed to antibiotics to which they were sensitive and samples exposed to antibiotics to which they were resistant. With the enhancement provided by SERS, the technique can be applied directly to urine samples leading to the development of a new, rapid method for UTI diagnosis and antibiogram.

Recently, a novel integrated optical waveguide 50/50 splitter was developed. It is fabricated using standard lithographic methods, a pair of etching steps and a laser reflow step. However, unlike other integrated waveguide splitters, the waveguide is elevated off of the silicon substrate, improving its interaction with biomolecules in solution and in a flow field. Additionally, because it is fabricated from silica, it has very low optical loss, resulting in a high signal-to-noise ratio, making it ideal for biosensing. By functionalizing the device using an epoxy-silane method using small samples and confining the protein solutions to the device, we enable highly efficient detection of CREB with only 1 μL of solution. Therefore, the waveguide coupler sensor is representative of the next generation of ultra-sensitive optical biosensors, and, when combined with microfluidic capabilities, it will be an ideal candidate for a more fully-realized lab-on-a-chip device.

Cryptosporidium parvum is a difficult-to-detect protozoan that causes diarrhea in the healthy adults and death in immunocompromised individuals. While it is easy to understand the transmission routes of Cryptosporidium, it is currently difficult to identify low concentrations of Cryptosporidium, especially when following EPA method 1623, which can easily require tens of liters of water to get a positive signal. The current detection method is unacceptable and severely inefficient when taking into account the time that goes into concentrating a sample, actual assays, and training associated with the assays. Using our method, it is possible to use only 15 μL of sample, which is an immunoagglutination assay that uses Mie scatter intensity changes to detect different Cryptosporidium concentrations. In addition to creating a standard curve using a clean sample matrix (i.e., phosphate buffered saline), field samples were collected from a chlorine treated swimming pool, a sump located on a farm, and a turtle pond. Each sample had different intensity changes but the trend represented within the data was the same. This assay has a detection limit of 100-101 oocysts/mL and can be done in as little as 10 minutes.

The challenge of correctly identifying malaria infection continues to impede our efforts to control this disease. Recent studies report highly specific retinal changes in severe malaria patients; these retinal changes may represent a very useful diagnostic indicator for this disease. To further explore the ocular manifestations of malaria, we used hyperspectral imaging to study retinal changes caused by Plasmodium berghei ANKA parasitization in a mouse model. We collected the spectral reflectance of the ocular fundus from hyperspectral images of the mouse eye. The blood oxygen sensitive spectral region was normalized for variances in illumination, and used to calculate relative values that correspond to oxygenated hemoglobin levels. Oxygen hemoglobin levels are markedly lower in parasitized mice, indicating that hemoglobin digestion by P. berghei may be detected using spectral reflectance. Furthermore, the ocular reflectance of parasitized mice was abnormally elevated between 660nm and 750nm, suggesting fluorescence in this region. While the source of this fluorescence is not yet clear, its presence correlates strongly with P. Berghei parasitization, and may indicate the presence of hemozoin deposits in the retinal vasculature. The pathology of severe malaria still presents many questions for clinicians and scientists, and our understanding of cerebral malaria has been generally confined to clinical observation and postmortem examination. As the retina represents a portion of the central nervous system that can be easily examined noninvasively, our technique may provide the basis for an automated tool to detect and examine severe malaria via retinal changes.

We are aiming at the realization of the non-invasive measurement of the biogenic-substance, such as the blood glucose concentration, by the proposed imaging-type 2-dimensional Fourier spectroscopy. We had successfully obtained the spectroscopic tomography of the mouse's ear with the near-infrared radiation. The proposed Fourier-spectroscopic imaging can limit the measuring depth into the focal plane. So, we can set the focal plane as the measurement plane near the skin surface that is not affected by the optical diffusion of the biological tissues. To analyze the absorption coefficient in the specific wavelength at the vessel area, we can expect to acquire the blood glucose concentration in high accuracy. In the proposed method, we install the variable phase-filter into the optical Fourier transform plane of the imaging optics to give the arbitrary phase-shift to the half flux of objective beams. Because of the imaging optics, only the rays from the focal plane can contribute the formation of the interferogram. Thus, we can obtain the 2-dimensional spectra only on the focal plane. We had successfully obtained the distribution of the spectroscopic-absorption near the skin surface. We are trying to convert the absorptance into the glucose concentration by the quantitative spectroscopic image-processing.

The application of optical polarimetry to glucose sensing in the anterior chamber of the eye has emerged as a potential technique to noninvasively ascertain blood glucose levels. One of the major limiting factors preventing the realization of such a device is the time varying corneal birefringence due to motion artifact in the eye. The varying birefringence confounds the optical activity of glucose, and thus, needs to be taken into account in order to successfully predict the glucose concentration in the aqueous humor of the eye. Our group has developed a multi-spectral optical polarimetric approach which can minimize the effect of corneal birefringence coupled with motion artifact by treating it as common mode noise to multiple wavelengths. Here, we present the application of a real-time closed-loop dual wavelength polarimeter to ex vivo glucose sensing in excised New Zealand White rabbits' corneas mounted on an artificial anterior chamber. Our PID control system can reach stability in less than 100 ms which is fast enough to overcome motion artifact due to heart beat and respiration. The system can predict the glucose concentration with a standard error of less than 26 mg/dL in the physiologic glucose range of 0 - 500 mg/dL. Our results indicate that dualwavelength polarimetry has the potential to noninvasively probe glucose through the anterior chamber of the eye.

Fluorescence lifetime-based glucose sensing does not depend on fluctuations of the intensity of the light source, light scattering, or changes in the transmission of optical components. Here we demonstrate the sensing of glucose based on the fluorescence lifetime properties of dihydro nicotinamide adenine dinucleotide (NADH), which is reduced from NAD in the presence of glucose and glucose dehydrogenase. In particular we use the difference in the fluorescence properties of free and protein-bound NADH and calculate an average fluorescence lifetime, which arises from the two short lifetimes τ₁=0.28ns and τ₂=0.60ns (representing free NADH) and the longer lifetime of τ₃=2.9ns (for the protein-bound NADH). While initial results were derived from measurements in aqueous solution, we also demonstrate the suitability of this method for determining the concentration of glucose in blood using test strips. We find that the average fluorescence lifetime changes linearly by a factor of 0.17 per 100mg/_dl change in glucose concentration. As an alternative the ratio between free and protein-bound components R_s/l may also be used for quantification. Rs/l increases by a factor of 0.74 per 100mg/dl change in glucose concentration.

Measurement of blood analytes, such as pH and glucose, provide crucial information about a patient's health. Some such analytes, such as glucose in the case of diabetes, require long-term or near-continuous monitoring for proper disease management. However, current monitoring techniques are far from ideal: multiple-per-day finger stick tests are inconvenient and painful for the patient; implantable sensors have short functional life spans (i.e., 3-7 days). Red blood cells serve as an attractive alternative for carriers of analyte sensors. Once reintroduced to the blood stream, these carriers may continue to live for the remainder of their life span (120 days for humans). They are also biodegradable and biocompatible, thereby eliminating the immune system response common for many implanted devices. The proposed carrier system takes advantage of the ability of the red blood cells to swell in response to a decrease in the osmolarity of the extracellular solution. Just before the membranes lyse, they develop small pores on the scale of tens of nanometers. Analyte-sensitive dyes in the extracellular solution may then diffuse into the perforated red blood cells and become entrapped upon restoration of physiological temperature and osmolarity. Because the membranes contain various analyte transporters, intracellular analyte levels rapidly equilibrate to those of the extracellular solution. A fluorescent dye has been loaded inside of red blood cells using a preswelling technique. Alterations in preparation parameters have been shown to affect characteristics of the resulting dye-loaded red blood cells (e.g., intensity of fluorescence).

Phantoms simulate optical characteristics of tissues. Phantoms use to mimic light distributions in living tissue. Several Phantoms compositions made of silicone, polyester, polyurethane, and epoxy resin have been described in the literature. These kinds of phantoms have the problem of long time preservation. In this work, we describe the fabrication and characterization of phantoms with low concentrations of synthetic lipid using Raman spectroscopy. We fabricate four phantoms made of Polydimethylsiloxane (PDMS). These phantoms have synthetic lipid content of cholesterol and triglycerides. The size of our phantoms is 1 x 1 cm and 5 mm of thickness.We used the point-to-point mapping technique. Finally, we compared advantages and performance of made PDMS and gelatin phantoms.

The use of Intralipid 20% was recently suggested as a diusive reference standard for tissue simulating phantoms. We herein extend previously obtained results to other fat emulsions, specically Intralipid 10%, Intralipid 30%, Lipovenoes 10%, Lipovenoes 20%, Lipofundin S 10%, and Lipofundin S 20%. Of particular importance for practical applications, our measurements carried out at a wavelength of 751 nm show the following features. First, batch-to-batch variations of the optical properties of these products are less than 2 % similarly to Intralipid 20%. Second, the absorption coecient of Intralipid, Lipovenoes, and Lipofundin S are very similar and their measured values are within the experimental errors. Third, the reduced scattering of Intralipid 20%, Lipovenoes 20%, and Lipofundin S 20% are similar and their measured values are within 5%. Forth, the reduced scattering coecient of Intralipid 10% and Intralipid 30% can be scaled from that of Intralipid 20% with an error of 9% and 2%, respectively. A similar scaling property is valid for Lipovenoes and Lipofundin S.

Various optical tissue phantoms (OTP) have been developed and utilized for the performance test of optical device and for in vitro human skin experiments. Solid OTPs have advantages such as semi-permanent use, convenience of experimental use, and easiness of storage. However, it is difficult to fabricate epidermis layer with an extremely thin layer of about few μm thickness. This study suggests a spin coating method to fabricate a thin layer which is similar to epidermis layer thickness of human skin (about 50 μm). By controlling specific parameters such as the concentration of matrix solution and the spin velocity for spin coating, we could design a solid OTP with extremely thin layer of about few μm and a good degree of planarization. Quantitative analysis was performed to evaluate both the spin velocity and the concentration of OTP matrix solution used to control specific thickness of OTP. By using optimal combination of parameters a specific thin layered OTP was fabricated with a thickness of less than 50 μm. In further studies, optimal combination of parameters needs to be studied to fabricate desired thickness of layer, depending on purpose.

In this paper, we describe the procedures to make epoxy resin and agarose phantoms designed using Mie scattering calculations. The phantoms are constructed to be used in the estimation of point spread function (PSF) of an optical coherence tomography (OCT) and evaluation of optical properties extraction (OPE) algorithm.

As hyperspectral imaging (HSI) sees increased implementation into the biological and medical elds it becomes increasingly important that the algorithms being used to analyze the corresponding output be validated. While certainly important under any circumstance, as this technology begins to see a transition from benchtop to bedside ensuring that the measurements being given to medical professionals are accurate and reproducible is critical. In order to address these issues work has been done in generating a collection of datasets which could act as a test bed for algorithms validation. Using a microarray spot printer a collection of three food color dyes, acid red 1 (AR), brilliant blue R (BBR) and erioglaucine (EG) are mixed together at dierent concentrations in varying proportions at dierent locations on a microarray chip. With the concentration and mixture proportions known at each location, using HSI an algorithm should in principle, based on estimates of abundances, be able to determine the concentrations and proportions of each dye at each location on the chip. These types of data are particularly important in the context of medical measurements as the resulting estimated abundances will be used to make critical decisions which can have a serious impact on an individual's health. In this paper we present a novel algorithm for processing and analyzing HSI data based on the LASSO algorithm (similar to "basis pursuit"). The LASSO is a statistical method for simultaneously performing model estimation and variable selection. In the context of estimating abundances in an HSI scene these so called "sparse" representations provided by the LASSO are appropriate as not every pixel will be expected to contain every endmember. The algorithm we present takes the general framework of the LASSO algorithm a step further and incorporates the rich spatial information which is available in HSI to further improve the estimates of abundance. We show our algorithm's improvement over the standard LASSO using the dye mixture data as the test bed.

Optical imaging has the potential to achieve high spatial resolution and high functional sensitivity in wound assessment. However, clinical acceptance of many optical imaging devices is hampered by poor reproducibility, low accuracy, and lack of biological interpretation. We developed an in vivo model of ischemic flap for non-contact assessment of wound tissue functional parameters and spectral characteristics. The model was created by elevating the bipedicle skin flaps of a domestic pig from the underlying vascular bed and inhibiting graft bed reperfusion by a silastic sheet. Hyperspectral imaging was carried out on the ischemic flap model and compared with transcutaneous oxygen tension and perfusion measurements at different positions of the wound. Hyperspectral images have also been captured continuously during a post-occlusive reactive hyperemia (PORH) procedure. Tissue spectral characteristics obtained by hyperspectral imaging correlated well with cutaneous tissue oxygen tension, blood perfusion, and microscopic changes of tissue morphology. Our experiments not only demonstrated the technical feasibility for quantitative assessment of chronic wound but also provided a potential digital phantom platform for quantitative characterization and calibration of medical optical devices.

Near infrared (NIR) fluorescence imaging has been successfully applied for non-invasive assessment of both lymphatic architecture and function as well as potential disease markers of lymphatic dysfunction in clinical studies with intradermal injection of indocyanine green (ICG). For new "first-in-humans" NIR fluorescence imaging agents that need to be employed at far lower quantities, NIR fluorescence imaging devices with high measurement sensitivity are most favorable. However, the measurement sensitivity of NIR fluorescence imaging devices is limited by various parameters, including quantum efficiency of CCD chip, noise sources in the CCD camera, and the leakage of excitation light through optical filters. In this contribution, we present a quantum dot-based fluorescence solid phantom and its use for characterization of excitation light leakage and measurement sensitivity in both the intensified CCD (ICCD) and Electron Multiplying CCD (EMCCD) based NIR fluorescence imaging devices. The stability of the constructed quantum dot-based fluorescence solid phantom was first demonstrated and used to demonstrate higher measurement sensitivity compared of the ICCD as opposed to the EMCCD based NIR fluorescence imaging device when integration time were maintained less than 1.0 s. The phantom was used to assess the calculated transmission ratio, R, to minimize noise owing to excitation light leakage and show optimized filtering capabilities. The constructed quantum dot based solid phantom and the methodology for measuring parameters of transmission ratio and SNR can be used as a standard and quantifiable metric for installation and operational qualification of all NIR fluorescence imaging devices.

We document our latest work in developing eye models with solid-state retinal tissue phantoms designed for demonstrating, validating and comparing ophthalmic Optical Coherence Tomography (OCT) instruments. Eye models with retina tissue phantoms can serve a variety of purposes, including demonstrating OCT functionality and performance in both the clinic and exhibit hall, validating retina layer thickness measurements from different commercial OCT instruments and as an aide for the R&D engineer and field service technician in the development and repair of instruments, respectively. The ideal eye model for OCT, the optical cross-sectional imaging modality, would have a volumetric morphology and scattering and absorption properties similar to that of normal human retina. These include a multi-layered structure of equivalent thickness to nominal human retina layers, a foveal pit that can be used to orient the image, and a RPE/OS and choroid like layers to demonstrate the depth penetration of the OCT system. A solid state tissue phantom relieves the user of constant cleaning and maintenance associated with the more common water bath model eyes. Novel processes12 have been developed to create retinal layers model that closely mimic the reflectance and scattering coefficients of the real layers of the retina, as imaged by spectral bandwidth of OCT.

The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs pulse duration. A series of lines in depth were etched, varying the percentage of inscription energy and speed of the translation stage moving the target with respect to the laser. Samples were imaged with a dual wavelength spectral-domain OCT system (λ=800nm, ▵λ≈180nm, and λ=1325nm, ▵λ≈100nm) and point-spread function of nanoparticles within the target was measured.

Optical tissue phantoms can serve many needs encountered in the translational path between fundamental research and clinical acceptance. Each of these needs call for a different set of requirements on the phantom design. Earlier stage research will require the phantom to reproduce adequately the measurement challenges of the intended application. Phantoms used during the final verification and validation phase of a medical device seeking FDA clearance will focus more on stability, repeatability and traceability. Developing and producing phantoms meeting these quality requirements is a challenging task. Unlike MRI or CT, optical technologies will not reach clinical practice as versatile multipurpose imaging platforms but as a collection of application specific instruments. This variety in the instrumentation translates into very diverse requirements for phantoms and is somehow a barrier to the standardization of diffuse optical spectroscopy. One common point of all diffuse optical spectroscopy instrumentation is the need for calibration which can be served by simple homogeneous reference material. A general consensus on the metrology of the optical properties of such reference material is required before it can become generally accepted by the community.

The adulteration of milk with harmful substances is a threat to public health and beyond question a serious crime. In order to develop a rapid, cost-effective, high-throughput analysis method for detecting of adulterants in milk, the discriminative analysis of melamine is established in milk based on the two-dimensional (2D) correlation infrared spectroscopy in present paper. Pure milk samples and adulterated milk samples with different content of melamine were prepared. Then the Fourier Transform Infrared spectra of all samples were measured at room temperature. The characteristics of pure milk and adulterated milk were studied by one-dimensional spectra. The 2D NIR and 2D IR correlation spectroscopy were calculated under the perturbation of adulteration concentration. In the range from 1400 to 1800 cm^-1, two strong autopeaks were aroused by melamine in milk at 1464 cm^-1 and 1560 cm^-1 in synchronous spectrum. At the same time, the 1560 cm-1 band does not share cross peak with the 1464 cm^-1 band, which further confirm that the two bands have the same origin. Also in the range from 4200 to 4800 cm^-1, the autopeak was shown at 4648 cm^-1 in synchronous spectrum of melamine in milk. 2D NIR-IR hetero-spectral correlation analysis confirmed that the bands at 1464, 1560 and 4648 cm^-1 had the same origin. The results demonstrated that the adulterant can be discriminated correctly by 2D correlation infrared spectroscopy.

On-site drug tests have gained importance, e.g., for protecting the society from impaired drivers. Since today's drug tests are majorly only positive/negative, there is a great need for a reliable, portable and preferentially quantitative drug test. In the project IrSens we aim to bridge this gap with the development of an optical sensor platform based on infrared spectroscopy and focus on cocaine detection in saliva. We combine a one-step extraction method, a sample drying technique and infrared attenuated total reflection (ATR) spectroscopy. As a first step we have developed an extraction technique that allows us to extract cocaine from saliva to an almost infrared-transparent solvent and to record ATR spectra with a commercially available Fourier Transform-infrared spectrometer. To the best of our knowledge this is the first time that such a simple and easy-to-use one-step extraction method is used to transfer cocaine from saliva into an organic solvent and detect it quantitatively. With this new method we are able to reach a current limit of detection around 10 μg/ml. This new extraction method could also be applied to waste water monitoring and controlling caffeine content in beverages.

We are aiming at the realization of the wide-field spectroscopic-imaging-sensor that is available for the health monitoring or the plant factory. Conventionally, the body temperature is measured by the thermography as a total intensity of the middle infrared radiation. We are trying to analyze the spectroscopic characteristics of the radiation heat from the human body in detail to measure the blood glucose or the moisture-retaining properties of the human skin. The proposed imaging-type 2-dimensional Fourier spectroscopy can measure the radiation heat from the object itself with the wide field of view and the wide wavelength-band. In this proposed method, we install the phase-shifter on the optical Fourier-transform-plane of the imaging optics to give the arbitrary phase-shift to the half flux of the object beams. Thus, the interferogram can be formed on the imaging plane in each bright point by the phase-shift interference-phenomena between the object beams that are emitted from the each corresponding bright point on the objective surface. In this report, we mention the feasibility results of the wide-field spectroscopic-imaging using the black body for the basic optical evaluation and the house plants for measuring the glucose distribution with the infrared camera(wavelength: 8μm-14μm).

Glucose specificity is the premise of spectroscopic measurements for blood glucose concentration, and it is also paramount for feasibility study of a spectral measurement method. Two-dimensional correlation spectroscopy technology is widely used in many fields such as inter-/intra-molecular reaction, material phase transition and information extraction because of its high resolution and the effective "sequential order" rules (Noda's rule). By using 2D correlation spectroscopy analysis, we aim at exploring glucose specificity for noninvasive glucose measurements from mid-infrared spectra collected from human beings. The study is mainly divided into two parts. The first part is to prove the realizability of the method by 2D correlation analysis of in vitro solutions which all contain glucose. And the second part is validating characteristic information of glucose from mid-infrared ATR spectra of human fingers by use of the 2D correlation spectroscopy technology. The conclusion is that glucose specific spectral information is really present in noninvasive mid-infrared in vivo spectra. So the feasibility of mid-infrared spectroscopy in noninvasive measurements of blood glucose concentration is demonstrated fundamentally.

A fluorescence polarization (FP) assay was developed to determine concentrations of glucose using concanavalin A (ConA) and fluorescently-labeled dextran. Predictive FP responses to glucose were elicited for different assay configurations using mathematical modeling and displayed herein. Using 4 kDa FITC-dextran, we predicted a change of 0.120 P units from 0 mg/dL glucose to 500 mg/dL. This shows the potential that a homogenous, reproducible FP assay can be engineered to measure glucose concentrations using tetrameric ConA and 4k kDa FITC-dextran.

We present Raman spectra from a sample of 8 volunteers that have different type of blood. The experimental data were carried out using a 785 nm excitation laser and an ocean optics spectrometer of 6 cm^-1 resolution, with a used spectral region from 1000 to 1800 cm^-1. We find Raman features at 1000 and 1542 cm^-1 regarded with hemoglobin and its derivatives. Also we find Raman features at 1248 and 1342 cm^-1 that are now regarded with pure fibrin. In this work, we use Principal Component analysis (PCA) to determine all variations of our samples, which allows us to define a classification of the influence of the blood type. Finally, we found vibrational lines of cholesterol, glucose and triglycerides that are reported in literature.

We have developed a snapshot fiber bundle technique that circumvents the issue of saccades of the non-immobilized eye. In this technology, 458 individual fibers are assembled in a two-dimensional array where each fiber represents a portion of the image. These fibers are redistributed into two separate one-dimensional fiber rows interfaced into a two-slit spectrometer. The light from each fiber is decomposed into its spectral components by the spectrometer. Using this innovative technology, we have been able to detect the whole spectrum of hemoglobin using the single light exposure capabilities of a fundus camera. The hemoglobin signature of the retinal arteries, veins, and retina tissue can be recorded. The final result is a complete, 3-dimensional representation of the spectral and spatial information from a single exposure of the patient. By adjusting the field of view on the imaging portion of the fundus camera, the fiber optic cable may encompass a larger area. However, this causes a decrease in spatial resolution, so we increased the area of the fiber array by increasing the number of the fibers from 458 to 648, increased the size of each individual fiber from 10 μm to 20 &μm, and increased the number of slits to four.

This work proposes the evaluation of the macronutrient constitution of human breast milk based on the spectral information provided by near-infrared Raman spectroscopy. Human breast milk (5 mL) from a subject was collected during the first two weeks of breastfeeding and stocked in -20°C freezer. Raman spectra were measured using a Raman spectrometer (830 nm excitation) coupled to a fiber based Raman probe. Spectra of human milk were dominated by bands of proteins, lipids and carbohydrates in the 600-1800 cm^-1 spectral region. Raman spectroscopy revealed differences in the biochemical constitution of human milk depending on the time of breastfeeding startup. This technique could be employed to develop a classification routine for the milk in Human Milk Banking (HMB) depending on the nutritional facts.

In the research of optical diagnosis, such as noninvasive measurement of blood glucose by near-infrared diffuse-reflectance spectroscopy, the fiber-optic probe are widely used to deliver light to the interested tissue site and collect the light from the tissue. In order to minimize motion artifacts and specula reflectance, the fiber-optic probe contact to tissue site with certain pressure. The spacing between tissue components decreased due to water displacement, while the volumes of cells and elastic fibers are reduced which in turn increase the concentration of the scatter and absorber inside the tissue. In our research a three-layer skin model is established and the Finite Element Method is employed to simulate the deformation of skin tissue caused by fiber-optic probe with different pressure. The change of water volume inside the tissue as well as the concentration and scattering cross section of scatters are considered. The Monte Carlo simulation is utilized to establish the diffuse-reflectance spectroscopy of three-layer skin model before and after compression. The result indicated that the pressure of fiber-optics probe should be controlled less the 50kpa to reduce the influence on measurement.

We report the construction and characterization at a wavelength of 633 nm of a polyurethane multi layered phantom with optical properties similar to a stratified model of human skin. During the construction of this phantom, integrating sphere technique was used to measure transmittance and reflectance, and using the inversion method IAD, to ensure that the optical properties of each layer corresponds to those in the design, measuring an exact replica of each one. A modified MCML code that includes the effects of lateral loss light and the spatial distribution of intensity at the entrance of the sample was used to compare the experimental transmittance and reflectance measurements of the whole phantom with the simulated ones obtained using the retrieved optical parameters in each layer.

In some vital organs of the human body the air bubbles are indicative of the presence of disease. On the other hand, poor information has been published considering the effect of air bubbles on the optical properties of tissue mimicking phantoms. The goal of this study was to investigate the influence of air bubbles on the optical properties of polyurethane phantoms. A two-integrating spheres system (TISS) in combination with the IAD method was used to determine the optical properties of a set of polyurethane phantoms fabricated with different levels of air bubbles. Phantoms were characterized with a microscope and a fiber optic spectrometer using a two-fiber probe. Results indicate that the TISS in conjunction with the IAD method is insensitive to the level of air bubbles within polyurethane phantoms whereas that for the spectrometric system a noticeable difference was found for the spectra of phantoms prepared with different levels of air bubbles. A change of reflectance spectra above 25 % at 428 nm was found when degassing sample time changed from 5 to 10 minutes. This finding indicates that controlling the degassing step of phantoms is more critical when they are required for the validation and standardization of devices that have a robust working principle based on the probing of a localized volume such as it is the case of fiber optic probes.

This PDF file contains the front matter associated with SPIE Proceedings Volume 8229, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.