This PDF file contains the front matter associated with SPIE Proceedings Volume 9715, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Recent developments in the identification of biomarkers offer a potential means to facilitate early disease detection, gauge treatment in drug therapy clinical trials, and to assess the impact of fatigue and/or stress as related to human physical and cognitive performance. For practical implementation, however, real-time sensing and quantification of such physiological biomarkers is preferred. Some key aspects in this process are continuous sample collection and real time detection. Traditionally, blood is considered the gold standard for samples but frequent phlebotomy is painful and inconvenient. Other sources like saliva and passive sweat cannot be precisely controlled and are affected by other limitations. Some of these can be addressed by reverse iontophoresis which is a noninvasive technique capable of facilitating controlled transport of biomolecules up to 20kDa in size across the skin barrier by passing a low level current between two dermal electrodes. The samples collected at the electrode site can then be monitored at site or transported via a microfluidic channel towards a sensor. In the case reported here, the sensor is based on surface plasmon resonance (SPR), which is a label free, real time, and highly sensitive optical sensing technique. The real time SPR detection of targeted biomarkers is then achieved through the use of aptamer surface modification. In this experiment, extraction and detection of orexin A, a stress related biomarker, is used for demonstration purposes.

Fibrinolysis is a process that regulates the breakdown of a blood clot to enable wound healing and is an essential component of hemostasis. Abnormalities in the fibrinolysis pathway may cause hyperfibrinolysis, associated with the increased risk of life-threatening bleeding particularly following acute trauma or major surgery. Assessing fibrinolytic activity in bleeding patients at the bedside can enable the timely administration of fibrinolysis inhibitors to improve prognosis. Optical thromboelastography (OTEG), a novel technique to assess blood coagulation status, has the potential to quantify fibrinolysis in real-time at PoC. The goal of the current study is to test the accuracy of OTEG in quantifying fibrinolytic status of human blood. Fibrinolysis is activated by adding varying concentrations of tissue plasminogen activator (tPA), a known fibrinolysis activator. The blood sample is illuminated by laser light and the resultant speckle intensity autocorrelation curve is used to derive changes in clot viscoelastic modulus during coagulation. From the OTEG trace, the coagulation parameters, clotting time (R), clot progression time (K), maximum clot strength (MA), and clot lysis (LY%) are derived. Our results indicate that increased tPA (0-0.5μM/ml) activation causes dose-dependent increase in LY% measured with OTEG: For instance, the addition of 0.5μM/ml of tPA increased LY% from 14.0 % to 81.5%. OTEG measurements also show a strong correlation with standard-reference mechanical Thromboelastography (TEG) measurements (N = 15, R=0.87, p<0.05). These results demonstrate that OTEG can accurately evaluate fibrinolysis and may provide the capability for identifying hyperfibrinolytic patients at an increased risk of life-threatening hemorrhage.

Bacterial infection causes Sepsis which is one of the leading cause of mortality in hospitals. This infection can be quantified from blood plasma using C - reactive protein (CRP). A quick diagnosis at the patient’s location through Point-of- Care (POC) testing could give doctors the confidence to prescribe antibiotics. In this paper, the development and testing of a bead-based procedure for CRP quantification is described. The size of the beads enable them to be trapped in wells without the need for magnetic methods of immobilization. Large (1.5 mm diameter) Polyamide nylon beads were used as the substrate for capturing CRP from pure analyte samples. The beads captured CRP either directly through adsorption or indirectly by having specific capture antibodies on their surface. Both methods used fluorescent imaging techniques to quantify the protein. The amount of CRP needed to give a sufficient fluorescent signal through direct capture method was found suitable for identifying bacterial causes of infection. Similarly, viral infections could be quantified by the more sensitive indirect capture method. This bead-based assay can be potentially integrated as a disposable cartridge in a POC device due to its passive nature and the small quantities needed.

This report demonstrates a method for high-resolution refractometric measurements using, what we have termed as, a Diffractive Interference Optical Analyzer (DiOpter). The setup consists of a laser, polarizer, a transparent diffraction grating and Si-photodetectors. The sensor is based on the differential response of diffracted orders to bulk refractive index changes. In these setups, the differential read-out of the diffracted orders suppresses signal drifts and enables time-resolved determination of refractive index changes in the sample cell. A remarkable feature of this device is that under appropriate conditions, the measurement sensitivity of the sensor can be enhanced by more than two orders of magnitude due to interference between multiply reflected diffracted orders. A noise-equivalent limit of detection (LoD) of 6x10^-7 RIU was achieved in glass. This work focuses on devices with integrated sample well, made on low-cost PDMS. As the detection methodology is experimentally straightforward, it can be used across a wide array of applications, ranging from detecting changes in surface adsorbates via binding reactions to estimating refractive index (and hence concentration) variations in bulk samples. An exciting prospect of this technique is the potential integration of this device to smartphones using a simple interface based on transmission mode configuration. In a transmission configuration, we were able to achieve an LoD of 4x10^-4 RIU which is sufficient to explore several applications in food quality testing and related fields. We are envisioning the future of this platform as a personal handheld optical analyzer for applications ranging from environmental sensing to healthcare and quality testing of food products.

Albumin plays an important role in human body. Its changed level in urine may indicate serious kidney disorders. We present a new point-of-care solution for sensitive detection of urine albumin - the miniature optical adapter for iPhone with in-built optical filters and a sample slot. The adapter exploits smart-phone flash to generate excitation light and camera to measure the level of emitted light. Albumin Blue 580 is used as albumin reagent. The proposed light-weight adapter can be produced at low cost using a 3D printer. Thus, the miniaturized detector is easy to use out of lab.

Metallothionein is significantly elevated in various tumors, notably in prostate cancer on both mRNA and protein level. We demonstrated a strong predictive potential of free circulating metallothionein 2A isoform mRNA for patients with this cancer. Circulating mRNA detection relies on expensive equipment and requires high level of expertise. In this work we developed compact "all-in-one" laboratory system which replace microvolume spectrophotometer, thermocycler and realtime PCR machines. We managed to design and construct a microprocessor controlled heating/cooling chamber that ensures required temperature gradient. The chamber includes implemented optical system to enable fluorescence excitation and fluorescence analysis using a smart-phone.

Point-of-care approaches for 3-part leukocyte differentials (granulocyte, monocyte, and lymphocyte), traditionally performed using a hematology analyzer within a panel of tests called a complete blood count (CBC), are essential not only to reduce cost but to provide faster results in low resource areas. Recent developments in lab-on-a-chip devices have shown promise in reducing the size and reagents used, relating to a decrease in overall cost. Furthermore, smartphone diagnostic approaches have shown much promise in the area of point-of-care diagnostics, but the relatively high per-unit cost may limit their utility in some settings. We present here a method to reduce computing cost of a simple epi-fluorescence imaging system using a Raspberry Pi (single-board computer, <$40) to perform a 3-part leukocyte differential comparable to results from a hematology analyzer. This system uses a USB color camera in conjunction with a leukocyte-selective vital dye (acridine orange) in order to determine a leukocyte count and differential from a low volume (<20 microliters) of whole blood obtained via fingerstick. Additionally, the system utilizes a "cloud-based" approach to send image data from the Raspberry Pi to a main server and return results back to the user, exporting the bulk of the computational requirements. Six images were acquired per minute with up to 200 cells per field of view. Preliminary results showed that the differential count varied significantly in monocytes with a 1 minute time difference indicating the importance of time-gating to produce an accurate/consist differential.

In military medicine, one of the challenges in dealing with large combat-related injuries is the prevalence of bacterial infection, including multidrug resistant organisms. This can prolong the wound healing process and lead to wound dehiscence. Current methods of identifying bacterial infection rely on culturing microbes from patient material and performing biochemical tests, which together can take 2-3 days to complete. Surface Enhanced Raman Spectroscopy (SERS) is a powerful vibrational spectroscopy technique that allows for highly sensitive structural detection of analytes adsorbed onto specially prepared metal surfaces. In the past, we have been able to discriminate between bacterial isolates grown on solid culture media using standard Raman spectroscopic methods. Here, SERS is utilized to assess the presence of bacteria in wound effluent samples taken directly from patients. To our knowledge, this is the first attempt for the application of SERS directly to wound effluent. The utilization of SERS as a point-of-care diagnostic tool would enable physicians to determine course of treatment and drug administration in a matter of hours.

Combat wounds are sometimes confounded by healing complications that are not as prevalent in civilian wounds due to their high energy etiology. One complication of wound healing is dehiscence, where a surgically closed wound reopens after closure. This complication can have serious consequences for the patient, but knowledge about the molecular composition of the wound bed beyond what is readily visible may help clinicians mitigate these complications. It is necessary to develop techniques that can be used in vivo to assess and predict wound healing pointof- care so that care-takers can decide the best way to make informed clinical decisions regarding their patient’s healing. Raman spectroscopy is a perfect candidate for predicting wound healing due to its ability to provide a detailed molecular fingerprint of the wound bed noninvasively. Here, we study the spectral correlation index, a measure of orthogonality, with ten reference tissue components to stratify wounds based on how they heal. We analyze these indexes over time to show the modulation of these tissue components over the wound healing process. Results show that qualitative observation of the spectra cannot reveal major differences between the dehisced and normal healing wounds, but the spectral correlation index can. Analysis of the spectral correlations across the wound healing process demonstrates the changes throughout the wound healing process, showing that early differences in tissue components may portend wound healing. Furthermore, Raman spectroscopy coupled with the spectral correlation index presents as a possible point-of-care tool for enabling discrimination of wounds with impaired healing.

Rapid assessment of radiation exposure to sensitive organs like the gut is extremely important for large populations exposed to ionized radiation, for instance during warfare. Recent results have shown that plasma citrulline levels appear to track gut function after irradiation levels in mice and humans. The current ways to monitor blood citrulline levels are bulky, laborious, time-consuming and expensive methods. Therefore, an optofludic point-of-care (POC) system using surface enhanced Raman spectroscopy to measure plasma citrulline as a marker for radiation exposure that overcomes the above issues is being developed.

As a first step toward development of this system four colloidal nanoparticles, spherical gold, silver cubes, silica-gold nanoshells, and silver-gold nanocages have been analyzed for use in the POC system. Transmission electron microscopy (TEM) images have been taken of each nanoparticle to visualize the morphology of the nanoparticles, which is vital for SERS. Ultraviolet-visible (UV/Vis) spectroscopy was also collected to verify the extinction spectra for each nanoparticle was in resonance with the excitation wavelength. The nanoparticles were functionalized with mercaptobenzoic acid (MBA), a Raman reporter molecule, and SERS spectra were collected to determine which has better utility in a novel micro-to-nanochannel. The data showed that the silver nanocubes have a larger enhancement factor than the gold nanospheres, nanoshells, or nanocages. Currently, these nanocubes are being functionalized with the citulline for assessing the concentration sensitivity and dynamic range for ultimate use as a marker for radiation.

We have developed the point-of-care therapeutic drug monitoring kit based on Raman Spectroscopy of tear fluid. In this study, we were examined a soft substrate for an optimal lattice based on nanoimprint lithography using cyclo-olefin polymer to improve the sensitivity for measuring drug concentration in tear fluid. This is photonics crystal which is one of the nano-photonics based device was fabricated. Target is Sodium Phenobarbital which is an anticonvulsant agent. We show the effectiveness of Surface Enhanced Raman Spectroscopy of tear fluid with soft substrate for point-of-care therapeutic drug monitoring.

We report two methods of surface enhanced Raman spectroscopy (SERS) for hemozoin detection in malaria infected human blood. In the first method, silver nanoparticles were synthesized separately and then mixed with lysed blood; while in the second method, silver nanoparticles were synthesized directly inside the parasites of Plasmodium falciparum.

In this article we propose a point-of-care screening device for the detection and identification of malaria parasite, plasmodium vivax, plasmodium malaria, plasmodium oval and plasmodium falciparum with a time frame of 15-20 minute. In our device we can provide 97-98% sensitivity for each species as we are using traditional staining methods for detecting the parasites. In addition, as we are also quantifying the parasites, it is possible to provide an accurate estimate about the malarial stage of the patient. The image processing approach increases the total numbers of samples screened by reducing interventions of trained pathologists. This helps in reducing the delays in screening process arising from increased number of potential cases based on seasonal and local variations. The same reduces mortality rate by faster diagnosis and reduced false negative detections (i.e. increased sensitivity). The system can also be integrated with telemedicine platform to obtain inputs from medical practitioners at tertiary healthcare units for diagnostic decision making. Through this paper, we present the functional prototype of this device containing all the integrated parts. The prototype incorporates image acquisition, image processing, storage, multimedia transmission and reporting environment for a low cost PDA device. It is a portable device capable of scanning slides. The acquired image will be preprocessed and processed to get desired output. The device is capable of transmitting and storing pathological information to database placed in a distant pathological center for further consultation.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains one of the most frequent causes of death worldwide. The slow growth rate of Mtb limits progress toward understanding tuberculosis including diagnosis of infections and evaluating therapeutic efficacy. Development of near-infrared (NIR) β-lactamase (BlaC)-specific fluorogenic substrate has made a significant breakthrough in the whole-animal imaging to detect Mtb infection. The reporter enzyme fluorescence (REF) system using a BlaC-specific fluorogenic substrate has improved the detection sensitivity in whole-animal optical imaging down to ~10⁴ colony forming units (CFU) of bacteria, about 100-fold improvement over recombinant strains. However, improvement of detection sensitivity is strongly needed for clinical diagnosis of early stage infection at greater tissue depth. In order to improve detection sensitivity, we have integrated a fiber-based microendoscpe into a whole-animal imaging system to transmit the excitation light from the fiber bundle to the fluorescent target directly and measure fluorescent level using BlaC-specific REF substrate in the mouse lung. REF substrate, CNIR800, was delivered via aerosol route to the pulmonary infected mice with M. bovis BCG strain at 24 hours post-infection and groups of mice were imaged at 1–4 hours post-administration of the substrate using the integrated imaging system. In this study we evaluated the kinetics of CNIR800 substrate using REF technology using the integrated imaging system. Integration of these technologies has great promise for improved detection sensitivity allowing pre-clinical imaging for evaluation of new therapeutic agents.

Cell counting in human body fluids such as blood, urine, and CSF is a critical step in the diagnostic process for many diseases. Current automated methods for cell counting are based on flow cytometry systems. However, these automated methods are bulky, costly, require significant user expertise, and are not well suited to counting cells in fluids other than blood. Therefore, their use is limited to large central laboratories that process enough volume of blood to recoup the significant capital investment these instruments require. We present in this talk a combination of a (1) low-cost microscope system, (2) simple sample preparation method, and (3) fully automated analysis designed for providing cell counts in blood and body fluids. We show results on both humans and companion and farm animals, showing that accurate red cell, white cell, and platelet counts, as well as hemoglobin concentration, can be accurately obtained in blood, as well as a 3-part white cell differential in human samples. We can also accurately count red and white cells in body fluids with a limit of detection ~3 orders of magnitude smaller than current automated instruments. This method uses less than 1 microliter of blood, and less than 5 microliters of body fluids to make its measurements, making it highly compatible with finger-stick style collections, as well as appropriate for small animals such as laboratory mice where larger volume blood collections are dangerous to the animal’s health.

This study investigates the feasibility of an endoscopic laser speckle imaging modality (ELSIM) in the measurement of perfusion of flowing fluid in optical bone tissue phantom(OBTP). Many studies suggested that the change of cochlear blood flow was correlated with auditory disorder. Cochlear microcirculation occurs under the 200μm thickness bone which is the part of the internal structure of the temporal bone. Concern has been raised regarding of getting correct optical signal from hard tissue. In order to determine the possibility of the measurement of cochlear blood flow under bone tissue using the ELSIM, optical tissue phantom (OTP) mimicking optical properties of temporal bone was applied.

The vascularization and resulting perfusion of transferred tissues are critical to the success of grafts in buried free flap transplantations. To enable long-term clinical monitoring of grafted tissue perfusion during neovascularization and endothelialization, we are developing an implantable instrument for the continuous monitoring of perfusion using diffuse correlation spectroscopy (DCS), and augmented with diffuse reflectance spectroscopy (DRS). This work discusses instrument construction, integration, and preliminary results using a porcine graft model.

Microcirculation is essential for proper supply of oxygen and nutritive substances to the biological tissue and the removal of waste products of metabolism. The determination of microcirculatory blood flow (mBF) is therefore of substantial interest to clinicians for assessing tissue health; particularly in pressure ulceration and suspected deep tissue injury. The goal of this pilot clinical study was to assess deep-tissue pressure ulceration by non-invasively measuring mBF using Diffuse Correlation Spectroscopy (DCS). DCS provides information about the flow of red blood cells in the capillary network by measuring the temporal autocorrelation function of scattering light intensity. A novel optical probe was developed in order to obtain measurements under the load of the subject’s body as pressure is applied (ischemia) and then released (reperfusion) on sacrococcygeal tissue in a hospital bed. Prior to loading measurements, baseline readings of the sacral region were obtained by measuring the subjects in a side-lying position. DCS measurements from the sacral region of twenty healthy volunteers have been compared to those of two patients who initially had similar non-blanchable redness. The temporal autocorrelation function of scattering light intensity of the patient whose redness later disappeared was similar to that of the average healthy subject. The second patient, whose redness developed into an advanced pressure ulcer two weeks later, had a substantial decrease in blood flow while under the loading position compared to healthy subjects. Preliminary results suggest the developed system may potentially predict whether non-blanchable redness will manifest itself as advanced ulceration or dissipate over time.

The feasibility of multi-wavelength photoplethysmography for the real-time sensing of absorptive and scattering agents in pulsatile blood is discussed. The use of pulsatile signals extracted from trans-illumination of an accessible section of tissue allows us to calculate the concentration of the optically extinctive species in the pulsatile blood. This technology, initially used for pulse oximetry and dye densitometry, can be applied to monitor in vivo concentration and clearance of various absorptive species. Recently, our prototype has been used monitor the concentration of therapeutic gold nanoparticles, antimalarial quinine, and the antifungal agent amphotericin B. The assessment of the optical properties, device specifications, and signal quality for each compound are presented. We observe that this technology can be used to monitor numerous extinctive drug and nano-materials that present features in the 350-1100 nm range. The rationale for using this technology in a clinical setting would be to improve outcomes by real-time pharmacological feedback and/or control at point of care in addition to the elimination of invasive blood draws for collection of data.

We present a new continuous-wave (CW) wearable diffuse optical device aimed at investigating the hemodynamic response of locally advanced breast cancer patients during a patient’s first neoadjuvant chemotherapy infusion. The system consists of a flexible substrate that supports an array of surface-mount LED and photodiode pairs (i.e. optodes). Probe performance was evaluated using solid tissue-simulating phantoms. Measurements revealed high SNR (65dB), low source-detector crosstalk (-59 dB), high measurement precision (0.17%), and good thermal stability (0.2% V_rms/°C). A cuff occlusion experiment was performed on the forearm of a healthy volunteer to demonstrate the ability to track rapid hemodynamic changes.

Vulvar lichen sclerosis (VLS) is a chronic, inflammatory and mucocutaneous disease of extragenital skin, which often goes undetected for years. The underlying causes are associated with the decrease of VEGF that reduces the blood oxygenation of vulva and the structural changes in the collagen fibrils, which can lead to scarring of the affected area. However, few methods are available for quantitative detection of VLS. Clinician’s examinations are subjective and may lead to misdiagnosis. Spectroscopy is a potentially effective method for noninvasive detection of VLS. In this paper, we developed a polarized, hyperspectral imaging system for quantitative assessment. The system utilized a hyperspectral camera to collect the reflectance images of the entire vulva under Xenon lamp illumination with and without a polarizer in front of the fiber. One image (I_par) acquired with the AOTF parallel to the polarization of illumination and the other image (I_per) acquired with the AOTF perpendicular to the illumination. This paper compares polarized images of VLS in a pilot clinical study. The collected reflectance data under Xenon lamp illumination without a polarizer are calibrated and the hyperspectral signals are extracted. An IRB approved clinical trial was carried out to evaluate the clinical utility for VLS detection. Our pilot study has demonstrated the technical potential of using this polarized hyperspectral imaging system for in vivo detection of vulvar lichen sclerosis.

The complex surface topology and soft mechanics of the skin poses a considerable challenge to the development of wearable, conformal sensors. As a results, current clinical assessments of healing-related skin parameters often rely on bulky and expensive optical systems that are difficult to deploy at the point of care. Here, using a rapid-drying, liquid bandage containing oxygen-sensing molecules, we created a wearable sensor bandage that conforms the surface geometry of skin and wounds, and provides two-dimensional maps of cutaneous oxygenation in a non-disruptive fashion. Custom oxygen sensing phosphors have been developed in house that are at least five times brighter than the commercial sensing molecules, enabling the visualization of oxygen concentration using a simple color camera or even by eye under ambient lighting conditions. The oxygen-sensing bandage has been applied to monitor tissue ischemia, graft integration, as well as the progression of burn in animal models. Recent studies have demonstrated its ability to track and quantify skin inflammation induced by complete Freund’s adjuvant in an in vivo porcine model.

This paper will describe a novel multi-wavelength photometric method to measure carboxyhemoglobin (COHb) and methemoglobin (MetHb) concentration non-invasively.

COHb and MetHb are so called dysfunctional hemoglobin derivatives and they are not able to carry oxygen. Standard pulse oximeters are only able to measure two derivatives, namely oxyhemoglobin (O₂Hb) and deoxyhemoglobin (HHb) but the presence of other derivatives in the blood may distort the readings. The paper presents a new approach of a noninvasive sensor system to measure COHb and MetHb and the validation in vivo and in vitro.

Blood glucose monitoring systems are important point-of-care devices for the hospital and personalised diabetes technology. FTIR-spectrometers have been successfully employed for the development of continuous bed-side monitoring systems in combination with micro-dialysis. For implementation in miniaturised portable systems, external-cavity quantum cascade lasers (EC-QCL) are suited. An ultra-broadly tunable pulsed EC-QCL system, covering a spectral range from 1920 to 780 cm^-1, has been characterised with regard to the spectral emission profiles and wavenumber scale accuracy. The measurement of glucose in aqueous solution is presented and problems with signal linearity using Peltier-cooled MCT-detectors are discussed. The use of larger optical sample pathlengths for attenuating the laser power in transmission measurements has recently been suggested and implemented, but implications for broad mid-infrared measurements have now been investigated. The utilization of discrete wavenumber variables as an alternative for sweep-tune measurements has also been studied and sparse multivariate calibration models intended for clinical chemistry applications are described for glucose and lactate.

Optical polarimetry is a promising noninvasive means of assessing glucose concentration in the aqueous humor of the eye. One the major limiting factors is time-varying cornea birefringence due to motion artifact, which prevents the realization of this device. In this study, we simultaneously utilize laser intensity modulation and Faraday polarization rotation modulation for a real-time closed-loop multi-spectral polarimeter for glucose monitoring in vitro. In this report, a real-time closed-loop dual-modulation dual-spectral polarimeter was presented and in vitro glucose measurements were performed demonstrating the accuracy and repeatability of this polarimeter.

We report the development of a versatile, cheap and reusable plasmonic sensor able to detect glucose in the physiological concentration range by means of a simple label-free optical detection scheme. In order to achieve the aforementioned goal we applied a self-assembly deposition technique for the large-scale arraying of mesoscale gold nanoshell particles. Different from metallic nanospheres arrays, the localized surface plasmon resonances of gold nanoshells arrays extend in both the visible and near-infrared range, making them extremely promising for their use in biological media. Furthermore, the optical response of mesoscale gold nanoshells arrays showed another remarkable characteristic, which is the presence of various Fano resonances that have the advantage of enhancing the sensitivity of the plasmonic substrate to the external media thanks to their sharp features and increased spectral contrast. The plasmonic sensor was shown to have an extended working range with a good linear response for large refractive index shifts, where a bulk refractive index sensitivity of 0.93 RIU^-1 (RIU, refractive index units) was achieved experimentally. In addition, the plasmonic sensor could detect aqueous glucose solutions in the blood concentration range (0-25 mM), with a sensitivity of 0.24 M^-1.

Optical imaging with fluorescent contrast agents is highly sensitive for molecular imaging but is limited in depth to a few centimeters below the skin. Planar fluorescence imaging with full-field, uniform illumination and scientific camera image capture provides a portable and robust configuration for real-time, sensitive fluorescence detection with scalable resolution, but is inherently surface weighted and therefore limited in depth to a few millimeters. At the NIR region (700–1000 nm), tissue absorption and autofluorescence are relatively reduced, increasing depth penetration and reducing background signal, respectively. Optical imaging resolution scales with depth, limiting microscopic resolution with multiphoton microscopy and optical coherence tomography to < 3 mm depth. Unfortunately, patient skin and peri-tumoral tissues are not uniform, varying in thickness and color, complicating subsurface fluorescence measurements. Diffuse optical imaging methods have been developed that better quantify optical signals relative to faster full-field planar reflectance imaging, but require long scan times, complex instrumentation, and reconstruction algorithms. Here we report a novel strategy for rapid measurement of subsurface fluorescence using structured light illumination to improve quantitation of deep-seated fluorescence molecular probe accumulation. This technique, in combination with highly specific, tumor-avid fluorescent molecular probes, will easily integrate noninvasive diagnostics for superficial cancers and fluorescence guided surgery.

In the non-keratinized epithelia, dysplasia typically arises near the basement membrane and proliferates into the upper epithelial layers over time. We present a non-invasive, multimodal technique combining high-resolution fluorescence imaging and broadband sub-diffuse reflectance spectroscopy (sDRS) to monitor health at various tissue layers. This manuscript focuses on characterization of the sDRS modality, which contains two source-detector separations (SDSs) of 374 μm and 730 μm, so that it can be used to extract in vivo optical parameters from human oral mucosa at two tissue thicknesses. First, we present empirical lookup tables (LUTs) describing the relationship between reduced scattering (μ_s') and absorption coefficients (μ_a) and absolute reflectance. LUTS were shown to extract μ_s' and μ_a with accuracies of approximately 4% and 8%, respectively. We then present LUTs describing the relationship between μ_s', μ_a and sampling depth. Sampling depths range between 210-480 and 260-620 μm for the 374 and 730 μm SDSs, respectively. We then demonstrate the ability to extract in vivo μ_s', μ_a, hemoglobin concentration, bulk tissue oxygen saturation, scattering exponent, and sampling depth from the inner lip of thirteen healthy volunteers to elucidate the differences in the extracted optical parameters from each SDS (374 and 730 μm) within non-keratinized squamous epithelia.

Optical spectroscopic technologies are increasingly used for cancer diagnostics. Feasibility of differentiation between malignant and healthy samples of human kidney using Fluorescence, Raman, MIR and NIR spectroscopy has been recently reported . In the present work, a simplification of NIR spectroscopy method has been studied. Traditional high-resolution NIR spectrometry was replaced by an optical sensor based on a set of light-emitting diodes at selected wavelengths as light sources and a photodiode. Two prototypes of the sensor have been developed and tested using 14 in-vitro samples of seven kidney tumor patients. Statistical evaluation of results using principal component analysis and partial least-squares discriminant analysis has been performed. Despite only partial discrimination between tumor and healthy tissue achieved by the presented new technique, the results evidence benefits of LED-based near-infrared sensing used for oncological diagnostics.

Publisher's Note: This paper, originally published on 4 March, 2016, was replaced with a corrected/revised version on 7 April, 2016. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.

Non-contact, imaging photoplethysmography uses photo-optical sensors to measure variations in light absorption, caused by blood volume pulsations, to assess cardiopulmonary parameters including pulse rate, pulse rate variability, and respiration rate. Recently, researchers have studied the applications and methodology of imaging photoplethysmography. Basic research has examined some of the variables affecting data quality and accuracy of imaging photoplethysmography including signal processing, imager parameters (e.g. frame rate and resolution), lighting conditions, subject motion, and subject skin tone. This technology may be beneficial for long term or continuous monitoring where contact measurements may be harmful (e.g. skin sensitivities) or where imperceptible or unobtrusive measurements are desirable. Using previously validated signal processing methods, we examined the effects of imager-to-subject distance on one-minute, windowed estimates of pulse rate. High-resolution video of 22, stationary participants was collected using an enthusiast-grade, mirrorless, digital camera equipped with a fully-manual, super-telephoto lens at distances of 25, 50, and 100 meters with simultaneous contact measurements of electrocardiography, and fingertip photoplethysmography. By comparison, previous studies have usually been conducted with imager-to-subject distances of up to only a few meters. Mean absolute error for one-minute, windowed, pulse rate estimates (compared to those derived from gold-standard electrocardiography) were 2.0, 4.1, and 10.9 beats per minute at distances of 25, 50, and 100 meters, respectively. Long-range imaging presents several unique challenges among which include decreased, observed light reflectance and smaller regions of interest. Nevertheless, these results demonstrate that accurate pulse rate measurements can be obtained from over long imager-to-participant distances given these constraints.

Intrathecal fluorescein (ITF) enhances detection of cerebrospinal fluid rhinorrhea (CSFR). Clinically administered doses fall in the range of 0.1ml to 0.5ml of 5% to 10% fluorescein (1.3×10^-3M to 1.3×10^-2M). Though uncommon, significant morbidities associated with high doses of fluorescein have been reported. High concentrations are necessary for white light visual assessment; in contrast, fluorescent imaging enhances signal contrast and requires lower ITF concentrations for visualization. The ultrathin and flexible, multimodal scanning fiber endoscope (SFE) can visualize nanomolar concentrations of fluorescein as pseudocolor over reflectance, video-rate imaging. The application of the SFE for CSFR detection was assessed in a cadaver study. Briefly, 10μM (1×10^-5M) fluorescein, 100X-1000X less than the standard clinical dose, was injected intra-cranially into the epidural space through an orbital roof puncture. The resulting rhinorrhea was assessed with a conventional, rigid ENT scope and second with the SFE in both video reflectance and multimodal fluorescent imaging modes. Neither system could visualize the 10μM ITF during white light imaging however the nanomolar sensitive SFE visualized the rhinorrhea during fluorescent imaging. Despite the low concentration used, a target-to-background ratio of 5.6 ± 2.7 was achieved. To demonstrate SFE guidance of CSFR detection and repair, de-identified patient computed tomography (CT) scans were used to generate 3D printed phantoms. Cases were selected for unique anatomical features and overall clinical difficulty as determined by an experienced ENT clinician (GED). The sensitivity and minimally invasive nature of the SFE provide a unique platform for enhancing diagnosis and monitoring interventions in surgical endoscopic approaches into the sinuses.

Non-contact measurement of pulse wave velocity (PWV) using red, green, and blue (RGB) digital color images is proposed. Generally, PWV is used as the index of arteriosclerosis. In our method, changes in blood volume are calculated based on changes in the color information, and is estimated by combining multiple regression analysis (MRA) with a Monte Carlo simulation (MCS) model of the transit of light in human skin. After two pulse waves of human skins were measured using RGB cameras, and the PWV was calculated from the difference of the pulse transit time and the distance between two measurement points. The measured forehead-finger PWV (ffPWV) was on the order of m/s and became faster as the values of vital signs raised. These results demonstrated the feasibility of this method.

Mid-infrared (MIR) spectroscopy is a valuable analytical method for patient monitoring within point-of-care diagnostics. For implementation, quantum cascade lasers (QCL) appear to be most suited regarding miniaturization, complexity and eventually also costs. External cavity (EC) - QCLs offer broad tuning ranges and recently, ultra-broadly tunable systems covering spectral ranges around the mid-infrared fingerprint region became commercially available. Using such a system, transmission spectra from the wavenumber interval of 780 to 1920 cm^-1, using a thermoelectrically cooled MCT-detector, were recorded while switching the aqueous glucose concentrations between 0, 50 and 100 mg/dL. In order to optimize the system performance, a multi-parameter study was carried out, varying laser pulse width, duty cycle, sweep speed and the optical sample pathlength for scoring the absorbance noise. Exploratory factor analysis with pattern recognition tools (PCA, LDA) was used for the raw data, providing more than 10 significantly contributing factors. With the glucose signal causing 20 % of the total variance, further factors include short-term drift possibly related to thermal effects, long-term drift due to varying atmospheric water vapour in the lab, as well as wavenumber shifts and drifts of the single tuners. For performance testing, the noise equivalent concentration was estimated based on cross-validated Partial-Least Squares (PLS) predictions and the a-posteriori obtained scores of the factor analysis. Based on the optimized parameters, a noise equivalent glucose concentration of 1.5 mg/dL was achieved.

In this paper, we introduce an innovative proposal for a low cost micro Raman spectrometer for non-invasive glucose monitoring. In this design, an Array Waveguide Grating (AWG) chip integrated with PIN photodiodes and a prism coupling are proposed to replace fiber micro alignment in packaging and to reduce system cost. Experiments were designed and conducted to evaluate the impact of thickness of the waveguides and the incident angle of the laser beam on the efficiency of the prism coupling. Considerable light coupling was observed when the waveguide core is 2mm thick. An updated fabrication process was designed and test chip was also fabricated to determine the critical feature size to solve the problem of air bubble resulted in trench filling.

In this study, we designed and simulated an array of bandpass filters as a spectral separator for mid-infrared self-emission noninvasive glucose monitoring, using the human body as the background radiation emitter. The filters were based on the guided-mode resonance (GMR) effect. The human body is a good black body radiator that provides a stable temperature and continuous radiation energy in the mid-infrared range. We can thus use self-emission from the human body to measure certain fingerprint peaks of glucose spectrum between 8 μm to 10 μm, which allows estimation of glucose concentration. The GMR filter set includes at least four filters on one chip fabricated at the same time. By using fixed thicknesses and the same thin-film material for all the filters on the chip, a structure period adjustment alone can theoretically achieve multiple bandpass filters between the glucose fingerprint ranges - and achieve these coplanar filters on a single chip. By using all CMOS-compatible materials, COMSOL simulations show that a series of peaks with transmittances up to 70% and bandwidths of around 200nm can be achieved. This filter set can be fabricated with just a few thin layers that can simplify the typical thin-film deposition process. The proposed GMR filter array can then be combined with a thermometer array to achieve the non-invasive glucose monitoring. We compare the results obtained with the first version of the fabricated filter set with the measurements of Fourier transform infrared (FT-IR) spectroscopy.

From the miniaturization of large sample processing machines to the creation of handheld point-of-care devices, microfluidics has the potential to be a powerful tool in the advancement of diagnostic technologies. Here, we compare different prototyping modalities towards the generation of an inertial microfluidic blood filter: i.e. a 'centrifuge-on-a-chip'. While photolithography is currently the method of choice for soft lithography mold fabrication, offering high design fidelity, we believe simpler methods, such as milling or 3D printing, will soon become equally viable options in the field of microfluidic device fabrication. Three modalities for optofluidic PDMS chip fabrication were compared: micromachining, 3D printing, and SU8 photolithography. The filtration efficiency of the chips were tested with whole blood and compared spectroscopically by monitoring the outlet absorbance at the 540 nm peak intrinsic to oxyhemoglobin at the outlet of each filter chip.

Focal cortical dysplasia (FCD) is one of most common causes of intractable epilepsy in pediatric population and these are often insensitive to anti-epileptic drugs. FCD is characterized by a disarray in localized regions of the cerebral cortex and abnormal neurons which results them to misfire with incorrect signals. Resective neurosurgery to remove or disconnect the affected parts from the rest of the brain seems to be a viable option to treat FCD. Before neurosurgery the subject could undergo imaging studies including magnetic resonance imaging (MRI) or computed tomography (CT) scans. On the downside FCD could be elusive in MRI images and may be practically invisible in CT scans. Furthermore, unnecessary removal of normal tissues is to be taken into consideration as this could lead to neurological defects. In this context, optical spectroscopy have been widely investigated as an alternative technique for the detection of abnormal tissues in different organ sites. Disease progression is accompanied by a number of architectural, biochemical and morphological changes. These variations are reflected in the spectral intensity and line shape. Here, in this proof of concept study we propose to investigate the application of tissue optical spectroscopy based on fluorescence excitation at two wavelength 378 and 445 nm coupled along with Raman spectroscopy for the detection of FCD on formalin fixed tissue specimens from pediatric subjects. For fluorescence at both the excitation wavelengths FCD showed a decreased intensity at longer wavelength when compared to normal tissues. Also, differences exist in the Raman spectral profiles of normal and FCD.

Identification and characterization of kidney stone remains one of the important analytical tasks in the medical field. Kidney stone is a common health complication throughout the world, which may cause severe pain, obstruction and infection of urinary tract, and can lead to complete renal damage. It commonly occurs in both sexes regardless of age. Kidney stones have different composition, although each stones have a major single characteristic component. A complete understanding of a sample properties and their function can only be feasible by utilizing elemental and molecular information simultaneously. Two laser based analytical techniques; Laser Induced Breakdown spectroscopy (LIBS) and Raman spectroscopy have been used to study different types of kidney stones from different patients. LIBS and Raman spectroscopy are highly complementary spectroscopic techniques, which provide elemental and molecular information of a sample. Q-switched Nd:YAG laser at 355 nm laser having energy 17mJ per pulse at 10 Hz repetition rate was used for getting LIBS spectra. Raman measurements were carried out using a home assembled micro-Raman spectrometer. Using the recorded Raman spectra of kidney stones, we were able to differentiate different kinds of kidney stones. LIBS spectra of the same stones are showing the evidence of C, Ca, H, and O and also suggest the presence of certain pigments.

In this study gas microbubbles are investigated as intravascular OCT contrast agents. Agar+Intralipid scattering tissue-like phantoms with two embedded microtubes were fabricated to model vascular blood flow. One was filled with human blood, and the other with a mixture of human blood and microbubbles. Swept-source structural and speckle variance OCT images, as well as speckle decorrelation times, were evaluated under both stationary and flow conditions. Faster decorrelation times and higher image contrast were detected in the presence of microbubbles in all experiments, and the effect was largest for speckle variance OCT ~2.3x greater contrast under flow conditions. The feasibility of utilizing microbubbles for tissue hemodynamic investigations and for microvasculature contrast enhancement in OCT angiography thus appears promising.

Skin health is characterized by heterogeneous system of water and lipids in upper layers providing protection from external environment and preventing loss of vital components of the body. Skin hydration (moisture) and sebum (skin surface lipids) are considered to be important factors in skin health; a right balance between these components is an indication of healthy skin and plays a central role in protecting and preserving skin integrity. In this manuscript we present inter- and intra-individual variation in skin hydration and surface lipids measured with a home-built experimental prototype based on infrared spectroscopy. Results show good agreement with measurements performed by commercially available instruments Corneometer and Sebumeter used for skin hydration and sebum measurements respectively.

Stable, relative localization of source and detection fibers is necessary for clinical implementation of quantitative optical perfusion monitoring methods such as diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS). A flexible and compact device design is presented as a platform for simultaneous monitoring of perfusion at a range of depths, enabled by precise location of optical fibers in a robust and secure adhesive patch. We will discuss preliminary data collected on human subjects in a lower body negative pressure model for hypovolemic shock. These data indicate that this method facilitates simple and stable simultaneous monitoring of perfusion at multiple depths and within multiple physiological compartments.