This PDF file contains the front matter associated with SPIE Proceedings Volume 10885, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Immunotherapy, an emerging field in cancer therapeutics, in colon cancer aims to reduce pre-surgical tumor burden by regulating host immune checkpoints, and when used in combination with neoadjuvant chemotherapy, may improve tumor therapeutic response. One such immune checkpoint is CCL2 (monocyte chemoattractant protein-1)-mediated recruitment of monocytes, which differentiate into tumor-associated macrophages (TAMs) in the tumor microenvironment that promote angiogenesis and tumorigenesis. Thus, CCL2 blockade may play an anti-tumor role via effects on tumor perfusion. However, there have been no studies investigating CCL2 blockade immunotherapy combined with chemotherapy in an animal model of colon cancer. Furthermore, there is a need to longitudinally assess tumor therapeutic response throughout treatment. In this study, CT26 murine colon carcinoma was injected into the flanks of Balb/c mice (n=80) to form tumor allografts. Mice in the key experimental group received combined chemotherapy (5-flurouracil) and immunotherapy (anti-CCL2), with appropriate controls. Tumor therapeutic response was monitored using diffuse reflectance spectroscopy (DRS) by measuring the tumor perfusion metrics, hemoglobin concentration and oxygenation. End-point immunohistochemical analysis was used to quantify TAM fraction (CD68 and DAPI), TAM polarization (iNOS and CD206), and hypoxia (pimonidazole) to spatially and temporally correlate to DRS results. The central hypothesis was that decreasing TAMs via CCL2 blockade alters tumor perfusion, thereby increasing tumor response to 5-fluorouracil. This study may potentially demonstrate an effective immunotherapy approach (CCL2 blockade) and a viable method to longitudinally and non-invasively assess tumor therapeutic response to such immunotherapy (DRS) in mouse allograft models of colon cancer.

For diagnostic imaging, a modality is required which has to be quick, inexpensive and noninvasive. Furthermore, risks for the patients have to be kept as low as possible since repetitive imaging might be required. To enable risk free imaging, hyper spectral imaging as tool for 3D tissue imaging is proposed to potentially meet all the above mentioned requirements. In this study, the first results of three dimensional reconstructions of hyper spectral images are presented. In general, the back reflected image consists of information from many different depths such that inclusions in different depths have a different effect on the back reflected images. Moreover, due to the wavelength dependent penetration depths, the spectral composition of the back reflected image changes in a different manner for different depths. This difference is normally not linear. However, due to a fine spectral resolution the difference can be assumed to be linear. The partial derivative of the wavelength is thus supposed to show the difference and allow the analysis. To demonstrate this, polyurethane phantoms are manufactured with TiO₂ as scatterer and ink as absorber. The inclusions are simulated by drilling holes into the phantom. The phantoms are imaged with a hyper spectral camera with a resolution of 51x765x1450 voxel (x, y, λ) from 400 to 800 nm. The spectral resolution due to the aperture is about 3 nm. In this study, first results are presented and a qualitative depths reconstruction is demonstrated. It is possible to show which inclusion is deeper with respect to the other.

Heart failure (HF) occurs when the heart is unable to pump enough blood to meet blood and oxygen requirements and is among the most common causes for hospitalization in the United States. A retrospective analysis determined that 22% of HF patients are readmitted within 30 days of release from the hospital, and the costs for readmission are substantial. Measuring the severity of peripheral edema is one method for monitoring the treatment of a HF patient. Pitting peripheral edema is a subjective measure administered by clinicians who create an indentation mid-tibia and observe depth and time to resolve the indentation. The results are graded 0, 1, 2, 3 or 4, and this information is used in the patient treatment plan. ChemImage is engaged in a clinical study to determine whether Molecular Chemical Imaging (MCI) in the short wave infrared (SWIR) spectral region can provide an objective measure of peripheral edema in HF patients. In this paper, the performance of SWIR MCI for discriminating between healthy volunteers and HF patients with high grade pitting edema will be presented. This technology may provide a non-invasive methodology for quantitative peripheral edema measurement. As the technology matures, it is envisioned patient self-monitoring, with wireless transmission of edema levels while at home, can aid clinicians in monitoring HF patients for necessary treatment changes remotely, to improve patient outcomes, and ultimately, reduce HF hospital readmission rates.

A decreased hemoglobin concentration (tHb) in blood (anemia) is associated with impaired oxygen delivery to organs, which can result in organ damage and heart failure. Currently, tHb analysis requires invasive methods (e.g. a fingerstick), which are time consuming and cause discomfort to the patient. Using optical spectroscopy, the tHb can be estimated by quantifying light absorption in blood. However, the accuracy of current noninvasive optical techniques for tHb quantification is limited by the background attenuation of skin and the unknown blood volume fraction in the total optical probing volume. Spectroscopic optical coherence tomography (sOCT) allows for quantitative measurements of the optical attenuation in a confined measurement volume, potentially enabling non-invasive estimation of the hemoglobin concentration within individual blood vessels. Although multiple studies have shown that sOCT is capable of quantifying localized oxygen saturation, quantification of the tHb has not yet been reported for physiologically relevant concentrations. With a home-built visible-light sOCT system we quantified optical attenuation in the visible wavelength range (450–600nm). Implementation of both zero-delay acquisition and focus tracking optimized system sensitivity and ensured that the measured attenuation is only affected by the attenuation of the sample itself. We validated our method ex-vivo on human whole blood from healthy volunteers (tHb within 12-18 g/dL). The hematocrit was varied to cover the entire pathophysiological range (tHb within 9-21 g/dL) by either dilution with PBS, or plasma removal. Our system quantified the tHb in whole blood throughout the entire pathophysiological range with an accuracy of 10%.

Central venous pressure (CVP) is a good surrogate for right atrial pressure, making it useful for assessing heart-related diseases. However, CVP is commonly assessed using invasive venous catheterization, rendering it infeasible for routine monitoring. Photoplethsymographic imaging (PPGI) is a biophotonic system that has recently shown to be capable of assessing the jugular venous pulse (JVP) waveform in a non-contact, widefield manner. Here, we monitored the effect of increased venous pressure on the JVP using a non-contact PPGI system. In this case study, the participant (22 year old healthy male) was positioned in a supine, right-tilted position so that the arm was below heart level with a continuous column of blood between the basilic vein and the right atrium to estimate CVP. The neck was illuminated with 940~nm uniform illumination, and a PPGI system, coded hemodynamic imaging, extracted the jugular venous pulse through a negative correlation filter using the arterial waveform. Data were collected at 0$^\deg$ and 8$^\deg$ head down tilt to alter the CVP due to changes in gravitational forces. Initial results show good agreement between the pulsatility of the jugular venous signal from the PPGI system compared and the pulsatility of the basilic venous pulse measured by a catheter placed into a vein. The PPGI data show changes in baseline pulsatility amplitude that reflect the changes in venous pressure moving from supine to 8$^\deg$ head down tilt transition, and are consistent in magnitude with measured CVP data.

We investigated a non-contact imaging method to evaluate plethysmogram and vasomotion with a digital color camera. Monte Carlo simulation for light transport in skin tissue is used to specify a relation among the red-green-blue-values and hemoglobin contents. Applying the FFT band pass filters to each pixel of the sequential images for the total hemoglobin concentration along the time line, two-dimentional plethysmogram and vasomotion can be reconstructed. In vivo experiments with human skin before, during, and after auditory stimulation demonstrated the feasibility of the method to evaluate the activities of autonomic nervous systems.

In present pilot study application of multi-spectral imaging photoplethysmography for assessment of chronic pain patients during topical skin heating test was proposed. Photoplethysmography signal was recorded at 420nm, 530nm and 810nm illumination from the skin and corresponding perfusion indexes and perfusion maps were calculated. The novel parameter-PPGflare index was introduced and compared in neuropathic patients and healthy volunteers. Preliminary results suggest that neuropathic patients exhibited significantly lower PPGflare index, and that local heating substantially change PPG waveform at heat exposed skin region. Present study emphasizes advantages of imaging photoplethysmography as a simple and cost-effective alternative to Laser Doppler with promising clinical potential in assessment of neuropathic patients. In this respect, we believe that our study adds novel information to the field of existing chronic pain diagnostics.

Very wide-field of view imaging can provide statistical data on large cell populations in a single acquisition. In this paper, we describe a multimodal imaging system combining brightfield, phase and fluorescence contrasts. Its greater simplicity and lower cost compared to flow cytometry make it suitable for Point-Of-Care applications. The system’s resolution was characterized on calibrated beads and resolution targets. We illustrate the potential of the single-shot imaging approach in hematology by studying the specific morphologies of white blood cell sub-types. The results suggest that very wide field of view imaging could be an alternative to flow cytometry for some applications in hematology.

At the primary care setting, defined by the World Health Organization (WHO) as an area with often no or minimal laboratories available, medical devices must be simple and easy to operate by users with a variety of skill levels. Because of these requirements, fluorescence microscopy has become a standard tool used in both high and low resource laboratories owing to its ability to identify fluorescently stained cells and sub-microscopic cellular components. An alternative design that could simplify the fluorescent microscope involves the use of ultraviolet (UV) illumination. While there is little documentation on fluorescence in the short range UV wavelengths, many fluorescent dyes that are excitable in the visible region are also excitable by UV. Based on this idea, we developed a simple fluorescence microscope built out of commercially available components which uses UV illumination and can image any fluorescent sample (given that the fluorophore can be excited by UV). Because UV is not typically visible on camera detectors and is absorbed by glass components, the separation of excitation light from emitted fluorescence may be easily incorporated into in the design of the microscope, eliminating the need for excitation, emission, and dichroic filters. The simplicity of the designed fluorescent microscope may allow for a more compact and easy to use microscope for the primary care setting as well as decrease the overall cost of manufacturing the device. For biological validation, we imaged whole blood stained with acridine orange (AO) and performed a two-part white blood cell (WBC) differential count.

Polymorphonuclear leukocyte (PMNL) count is employed as an immune status indicator for diagnosis of numerous medical conditions. Currently, assessment of PMNLs (i.e., neutrophils, eosinophils, basophils) is a part of complete blood count (CBC) that is performed by trained technicians at healthcare centers and involves sample preparation which is costly and time consuming, both of which limits monitoring frequency. A prominent application of PMNL counting is in identification of neutropenia—a condition describing an abnormally low number of neutrophils in the bloodstream (<1500/μL)—common among cancer patients receiving chemotherapy. Susceptibility to infections in neutropenia patients puts them at an increased risk for medical emergencies, and thus requires constant monitoring of their neutrophil count. Therefore, a portable and easy-to-use, in-home device can potentially circumvent these requirements and enable neutropenia diagnosis. In this work, we demonstrate the feasibility of accurately identifying PMNL subtypes using deep-ultraviolet (UV) microscopy as label-free molecular imaging technique. Our approach benefits from quantitative endogenous molecular information provided by deep-UV imaging, to enable assessment of different cell types based on their molecular and structural signatures. We show the ability of our system to measure neutrophil count in samples containing a mixture of PMNL subtypes as well as whole blood samples by extracting various features from deep-UV images and performing classification to obtain cell count for each subtype. Finally, we will discuss the potential of this technology to empower cancer patients and improve their quality of life via a simple and relatively inexpensive device for point-of-care neutropenia assessment.

Inflammatory tissue response is one of the first and most common manifestations of acute graft-versus-host disease (aGVHD), a potentially deadly immune-mediated disease that occurs in 30-60% of patients after stem cell transplantation. A fundamental challenge in developing effective treatment strategies for aGVHD is the lack of tools to study disease biology in real-time in post-transplant patients. The inflammatory tissue response causes increased expression of specialized endothelial proteins on vessel walls making leukocytes to roll, adhere and eventually extravasate into the tissue at a higher rate than in normal conditions. Although the importance of leukocyte-endothelial interactions to detect and track inflammation has been well shown in murine models, there are no published clinical studies in humans. In this study, we explore the feasibility to detect presence of aGVHD in post-transplant patients through the imaging of in vivo leukocyte motion. We used a clinical confocal microscope (Vivascope 1500) to acquire videos of 5 aGVHD patients and 5 controls (no aGVHD) within 50±30 days post-transplant. The microscope is capable of real-time imaging of individual cells in the postcapillary vessels at 9 frames per second. Through video analysis, we extracted five quantitative parameters: number and velocity of rolling leukocytes, number of adherent leukocytes (stationary >30 s), blood flow velocity, and number of vessels. In a limited number of subjects, we show that parameters characteristic of the dynamic motion in skin capillaries can be observed noninvasively in post-transplant patients. Further studies are needed to test the diagnostic potential of these parameters.

The tissue of the extracellular matrix (ECM) are made up of distinct structural proteins, including different types of collagens. Intrinsic autofluorescence lifetimes of ECM proteins offer a non-contact, label-free characterization of tissues. This is especially useful in monitoring wound healing, where differentiating between different tissue matrix signatures can assist in evaluating the tissue structure underneath. Our previous work has demonstrated distinction between collagen types from bovine and human tissues. In this abstract, we are applying our frequency domain imaging technique to look at burn wounds in porcine skin. In this abstract, we measured normal skin tissues and compared their frequency domain lifetime scans to superficial burn tissues (80°C for 20 s) that have been healing for 21 days. Hairs were plucked from all samples prior to the scans. Each sample was scanned with 5 millimeter by 5 millimeter area at 70 µm step resolution. The scans were modulated at 20 MHz and the acquired tissue intensities were then calculated using Fast Fourier Transform and fitted to a two-exponential decay model per our previous work. The autofluorescence lifetime of the normal skin sample showed a uniform lifetime of 6.9±0.5 ns (n=8). The burn wound tissue showed an increase in lifetime to 7.4±0.6 ns (n=12). The data suggests that as wound tissue heals, in this case porcine burn model, the autofluorescence lifetime is altered, signifying potential correlation to the collagen remodeling underneath. This can be used to determine the effect of treatments on wound healing in a noninvasive nondestructive manner.

Introduction: Current clinical practice guidelines for acute spinal cord injury (SCI) patients suggest that increasing the mean arterial pressure (MAP) to 85-90 mmHg may improve spinal cord (SC) hemodynamics and oxygenation. The purpose of this study was to examine this effect using an implantable Near Infra-Red Spectroscopy (NIRS) sensor. Methods: Nine anesthetized Yorkshire pigs were studied. A multi-wavelength NIRS system with a custom-made miniaturized optical sensor was applied directly onto the SC dura at T9 to measure tissue oxygenation and hemodynamics within the SC non-invasively. To validate the NIRS measures, an invasive Intraparenchymal (IP) combined O2/blood flow sensor was inserted directly into the SC adjacent to the NIRS probe at T11. Using NIRS, the SC tissue oxygenation percentage (TOI%), as well as concentrations of oxygenated, deoxygenated and total hemoglobin, were monitored before, during and after episodes of MAP alterations. Using norepinephrine and nitroprusside, MAP was increased and decreased by 20mmHg for 30 min periods, simulating the types of hemodynamic changes that SCI patients experience post-injury. Results: Changes in SC hemodynamics and oxygenation levels were detected in all subjects as measured by both the invasive IP and the non-invasive NIRS sensors. Changes of TOI% during MAP increase (1.64%, p<0.005) and decrease (-3.97%, p<0.005) were significant. A consistent decrease in TOI (-15.94%, p<0.005) was observed following SCI, indicating SC tissue hypoxia at the injury site. Conclusions: Using a miniaturized SC NIRS sensor we have shown the significant effect of MAP alterations on tissue oxygenation within the injured SC.

In this paper, we analyzed the current situation and the potential of biophotonics and biomedical optics in veterinary medicine. Promising optical techniques such as optical coherence tomography, pulse oximeter, and hyperspectral imaging have been clinically translated into human medicine. But even though human and small animal medicine share personalized and state-of-the-art approach, biophotonics remains rarely exploited in the canine and feline medicine. However, there are some biophotonics studies in veterinary oncology which addressed tumor diagnosis (skin and subcutaneous tumors), prognosis (lymphoma), and therapy (clear surgical margins). Visible and near-infrared spectroscopy served for measuring various physiological parameters related to circulation, and photobiomodulation therapy was often used for the management of wounds, skin conditions, and orthopedic problems. In the research, the most popular clinically translated technique is thermography which was applied for the diagnosis of orthopedic problems and diseases as infections and hyperthyroidism. The future optical devices for small animals such as dogs and cats should be robust and resilient to damage (e.g., due to biting, chewing), offering user-friendly and short measurements. In veterinary oncology, biophotonics could replace invasive fine-needle aspiration procedure. The potential of a pulse oximeter for pet monitoring has yet to be explored. What is more, photobiomodulation efficiency should be tested in an extensive clinical (in vivo) study. The technique would be very beneficial in dentistry which currently requires expensive and risky anesthesia.

Optical waveguides using a visible transparent nitride were developed to perform fluorescence measurement on a chip. Through finite difference time domain (FDTD) design, the exciting green light was guided by the micron-scale ridge waveguide, while its evanescent wave was expanded outside the waveguide surface and capable to efficiently excite the fluorescent molecules that were approaching the waveguide facets. Since the waveguide was centimeters long, it has a longer fluorescence excitation path comparing to traditional samples prepared for microscopy measurements. As result, the waveguide device can excite stronger fluorescent signals. In addition, the nitride waveguide was prepared by the complementary metal–oxide–semiconductor (CMOS) process thus enabling high volume manufacturing and reducing the cost of the device fabrication. The AlN waveguide was then integrated with a microfluidic devices to experimentally demonstrate real-time fluorescence detection. Solution samples with different dye concentrations were sequentially injected into the microfluidic chamber. By recording the emission signals, we showed that the fluorescent signals were consistently amplified as the dye concentrations increased. In addition, real-time fluorescence detection with a response time less than seconds was achieved. The developed waveguide based fluorescence measurement provides a new miniaturized platform for low cost and highly accurate point-of-care application.

In this paper, we propose a compact real time polymerase chain reaction (PCR) system for detecting fluorescence of PCR chips. Various fluorescence detection methods have been studied, but all require many optical components and optical distances. Therefore, this paper proposes a system to detect fluorescence by attaching LED and photodiode directly to reagent surface. This system is very compact and inexpensive because it requires no optical component except only excitation and emission filters. In order to optimize the performance of the proposed system, we investigated the placement of LEDs and photodiodes, the choice of filters, the signal amplification circuit, and air bubble problems during PCR amplification. Modification of the PCR protocol to obtain better results have also been studied. PCR amplification experiments on real DNA samples showed that the proposed system works well and compactness and portability are greatly increased compared to the conventional system.

Neonatal Jaundice is a common condition in newborns caused by excess bilirubin accumulating in the blood. Bilirubin is a neurotoxin and if left untreated can cause permanent neurological impairment or death. Jaundice resulting from unconjugated hyperbilirubinemia can be easily treated using blue light phototherapy, and several low-cost treatment systems have been built for low-resource settings. However, there is still a lack of an appropriate low-cost diagnostic. To address this, we present BiliSpec, a low-cost paper lateral flow disposable and reader to measure total bilirubin from whole blood. The system can be used at the point-of-care and measure bilirubin concentration within minutes. The accuracy correlates well with a reference laboratory standard (r = 0.996). We then performed a pilot clinical study using BiliSpec at Queen Elizabeth Central Hospital in Blantyre, Malawi. Bilirubin concentrations measured with BiliSpec correlated well with a laboratory reference standard in a 94 patient study (r = 0.973). Bilirubin concentrations measured ranged from 1.1 mg/dL to 23.0 mg/dL. The mean difference between BiliSpec and the laboratory standard was 0.3 mg/dL (95% CI: −1.7–2.2 mg/dL).

Nonessential amino acids (NEAAs) are the building blocks for producing proteins of various functionalities within living systems. For example, from NEAAs, humans produce proteins that are important for cell repair, cell division and synthesis of hormones paramount to maintaining a healthy body. Understanding the chemical properties of NEAAs can therefore allow a thorough investigation of biological processes in the cases of ailing individuals. Raman spectroscopy has become a powerful technique for characterizing various organic compounds such as NEAAs, relying on their unique light scattering properties. In this study we present a custom built Raman Spectroscopy system which was used to investigate and calibrate a group of NEAAs through a comparison of peak area versus concentration. The results show that various regions of interest within the sample mixtures exhibit an increase in signal intensity when the concentration is increased. This is in agreement with current literature on the parameters that effect Raman systems such as concentration. Secondly, it was observed that 0.1 mM of NEAAs was the current detection limit of the system in terms of number of significant peaks produced. As a result, it is important that future work includes incorporating nanomaterials as sample scaffolds for signal enhancement to improve sensitivity. Much of this work is intended towards producing a point-of-care diagnostic tool for analysis of cancer agents.

Amino acids are the basic “building blocks” of peptides and proteins and play important roles in the physiological processes of all species. In this study, we simulated the Raman spectrum of Glycine, Tyrosine and Phenylalanine using General Atomic and Molecular Electronic Structure System (GAMESS) and Gaussian, two computational codes that perform calculations of electronic and vibrational properties of molecules. Through our work, strong bands with N-H and O-H bonds and with benzyl ring were pinpointed and identified. Our work presents insights into the importance of intermolecular bonding of amino acids in the life and physiological processes, including metabolism, signal transduction, and neurotransmission etc.

Raman spectroscopy is a powerful tool in biomedical imaging and sensing; however, despite all its undisputed advantages, its intrinsic sensitivity is relatively low, and its specificity is rather limited due to overlapping vibrational bands. Fluorescence background often masks the useful signal, and dark rooms are normally required to avoid an unnecessary background. In this report, we will present our recent efforts on improving reliability and simplicity of deep UV Raman spectroscopy, which provides much improved sensitivity and specificity of detection (for example, we can routinely distinguish Coke® from Diet Coke® in a matter of milliseconds).

Non-invasive blood glucose measurement has long been desired since the invasive methods are not suitable to perform continuous monitoring. Near Infrared Spectroscopy is one of the most popular methods used in studies; however, despite more than 20 years of research, a practical and reliable noninvasive NIR glucose sensor is yet to be developed. In this study, we investigated the feasibility of NIRS towards the detection of glucose concentration. Although we can obtain adequate sensitivity, our measurements suffer from poor selectivity due to the fact that we can only detect the impurity level of water by NIRS due to strong water absorbance.

In the non-invasive blood glucose sensing based on near-infrared spectroscopy, the skin scattering variation during the long-term blood glucose monitoring would be a big challenge to get an accurate measurement result. We present a scattering and absorption separating method for the near-infrared diffuse reflectance spectra of scattering media. And we use the extracted absorption part, which is the medium’s effective attenuation coefficient (EAC) spectrum, to improve the accuracy for long-term glucose monitoring. We optimized the light source-detector separation (SDS) setup to realize the maximum sensitivity for the EAC spectra-based measurement. The measurement uses two SDSs to perform a differential on their diffuse reflectance spectra, as the differential could help to reduce the light drift during the long-term in vivo tissue monitoring. The SDS setup optimization for the two positions was tested by the Monte-Carlo (MC) simulation of tissue. The human oral glucose tolerance test (OGTT) with the optimized SDSs also shows a satisfactory blood glucose prediction result. In conclusion, this method shows a good application potential in the non-invasive blood glucose sensing.

Spectral region beyond 1.7 μm is particularly interesting for biomedical spectroscopic sensing applications due to the presence of strong and molecule-specific ro-vibrational overtone and combination absorption bands for a number of important analytes such as glucose, lactate, urea, human serum albumin among others. However, this spectral region has been largely unexplored for applications targeting wearable device technology due to the absence of commercially available semiconductor light source technology. In this work we report on recent progress in developing beyond-stateof-the-art GaSb-based swept-wavelength laser technology as a key building-block of the proposed spectroscopic sensor concept. To demonstrate the capability of the technology, we provide experimental data of in vitro sensing concentrations down to the normal physiological range and beyond for glucose, lactates, urea and bovine serum albumin. Furthermore, we provide initial experimental evidence of non-invasive in vivo sensing experiment with extracted absorbance signature of human serum albumin collected from the wrist and demonstrate a clear path towards sensing other analytes. Finally, to demonstrate the full potential of the spectroscopic sensor technology for the wearable device market, we present results of our initial effort to realize a complete spectroscopic sensor system-on-a-chip based on hybrid GaSb/Si material platform and manufactured using conventional 200 mm silicon-on-insulator CMOS technology process in a commercial high-volume foundry.

We propose the point one-shot mid-infrared Fourier spectroscopic imager, which is composed of only a single Ge lens (diameter: 6 mm; thickness: 5 mm) and a two-dimensional array device. The lens is a nonspherical lens on the front side and a dual-axis inclined wedge prism at the rear side. The objective beams, which have different optical path lengths because of the effects of the prism, are imaged using the array device and we obtain a two-dimensional spatial fringe pattern. We can improve the wavelength resolution analytically by connecting the same optical path difference (OPD) pixels of the horizontal lines at different rows, even though we use low-resolution cameras.

For monitoring and prevention of lifestyle diseases, we have investigated development of non-invasive ear-clip type blood glucose sensors that can be used by individuals in daily life. Because mid-infrared light (λ = 8–14 μm) is absorbed strongly by water, it is difficult to detect transmitted light from human bodies. We propose that an ultrasonic-assisted method, which can actively produce a reflection plane at a blood vessel (depth of around 100 μm), could be used to detect internal reflected light from biological tissues. An ultrasonic standing wave produced near the skin surface by an ultrasonic vibrator can form refractive index boundaries between areas of high and low density. Additionally, we can use a low ultrasonic frequency (1 MHz) that does not suffer from heavy damping by parametric standing waves, which appear in non-rigid samples and produce reflection planes at the same depth when using a high frequency (10 MHz). At the refractive index boundary nearest the skin surface, the light from inside biological tissues is reflected and can be used to obtain information of biological components. The optical path length can be set by changing the measurement depth by altering the ultrasonication frequency. We measured internal reflected light from the ears of mice (blood glucose level = 120 mg/dL) non-invasively using our unique mid-infrared spectroscopic imager and obtained absorption peaks for blood glucose (λ = 9.3 μm and 9.7 μm). Mid-infrared spectroscopy can be applied to measurements in samples with high water contents.

We present a scattering-independent measurement to monitor the pure near-infrared light absorption variation for scattering media, especially for in vivo tissue. We found a scattering variation independent source-detector separation (SVI-SDS), where the diffuse light intensity only varies with tissue absorption change but does not vary with scattering change. We applied the SVI-SDS setup to monitor the tissue spectra with a temperature modulation. We also proposed a method to simplify the measurement by using two fixed SDSs for all wavelengths. It makes the detection device easy to design and fit to the required SVI-SDSs. Monte Carlo simulation and experiments on intralipid solutions and in vitro pig skin samples are performed to test the method. The temperature absorption spectra were acquired, and the temperature insensitive wavelengths of the tissue are discussed. We believe this new method will guide many potential applications for the absorption-based tissue spectroscopy.

Diabetes management is reliant on consistent and accurate monitoring. Low patient compliance for the standard finger prick test along with its intermittent nature may lead to undetected highs and lows. In 2014, poor glycemic control caused 207,000 hospitalizations from hyperglycemia and 245,000 hospitalizations from hypoglycemia in the US. The implementation of continuous glucose monitors (CGMs) can provide a more thorough illustration of blood glucose level fluctuations. Currently, there are several transcutaneous CGMs produced by Abbott, Dexcom, and Medtronic along with a fully implantable option by Eversense. Improvements to both the sensitivity and size of CGMs are being studied by our group through the development of a competitive binding, FRET-based, glucose biosensor that is fully implantable and probed optically with an external “watch-type” device. In previous work, our group has successfully developed an assay, but due to the near-UV excitation wavelength range, there are limitations in decreased skin penetration depth along with excess noise due to autofluorescence of the tissue. In this work, we investigated the FRET response through skin samples of both Blue (APTS) and near infrared (NIR) (Alexa Fluor 700 and 750) dyes. These dye samples were encapsulated within previously reported hollow, cylindrical, thermoresponsive hydrogel membranes and the fluorescence intensity signals were compared when placed beneath thin and thick (0.87 and 1.85 mm) rat skin samples. The FRET response of AF-700 and AF-700 was measured when placed beneath thicker skin samples of both lighter and dark pigmentations. The results indicate that the use of NIR dyes is needed to allow for a reasonable implantation depth for the implantable biosensor.

We have developed a system of flexible optical imaging bands that can be used to assess the effects of systemic lupus erythematosus (SLE) on finger joints. Each imaging band consists of four pairs of light sources and a photodetector. The light sources contain three different light emitting diodes with wavelengths of 530 nm, 655 nm and 940 nm. Two of these imaging bands are wrapped around the proximal interphalangeal (PIP) joints of the index-, middle-, and ringfingers. The imaging bands gather transmitted and reflected light intensities from the tissues for ~ 4 minutes including two venous occlusions. This results in hemodynamic time traces for all source-detector pairs. From theses traces a rise, plateau, and fall time are calculated. We found that, on average, signals obtained from SLE patients displayed a shorter rise time and longer plateau time as compared to signals from healthy controls. Performing a two-dimensional linear discriminant analysis on the rise and plateau times, we obtained the best specificity of 89% and the best sensitivity of 76 %. Area under the receiver operating characteristic (ROC) curve is 0.86.

Analog mean-delay (AMD) method is a new powerful alternative method in determining the lifetime of a fluorescence molecule for high-speed confocal fluorescence lifetime imaging (FLIM). The major advantage of this method is that the mean delay effect caused by a slow measurement system can be completely removed. The measurement speed can be very fast compared to the conventional TCSPC method because the AMD method can detect multiple photons simultaneously for a single excitation pulse. More accurate fluorescence lifetimes can be determined with more photons such that an accurate fluorescence lifetime image can be acquired quickly by the AMD method. In this study, we demonstrated cancer discrimination based on real-time AMD(Analog Mean-Delay)-FLIM(Fluorescence Lifetime Imaging Microscopy). We subcutaneously injected MDA-MB-231 breast cancer cell lines into nude mice. After subcutaneous (SC) injection of sodium fluorescein, the fluorescence lifetime of sodium fluorescein was measured by real-time AMD-FLIM. The fluorescence lifetime of sodium fluorescein depends on the local pH and pH differs between abnormal and normal tissues, cancer tissue can be discriminated from normal tissue by measuring the fluorescence lifetime of pH-sensitive sodium fluorescein. The measured fluorescence lifetime of sodium fluorescein inside the normal and abnormal tissues were 4.15~4.28 ns and 2.36~3.18 ns. Since the measured fluorescence lifetime for abnormal tissues were well differentiated from those for normal tissues, the fluorescence lifetime of sodium fluorescein could be used as an indicator to increase the accuracy of cancer detection with confocal microscopy or endoscopy.