Abstract: Optical sensors, systems, and methods are described, which may be used to provide or analyze information about a subject. The optical sensor may be placed in proximity to the subject and may include optical sources and optical detectors. The optical sources may irradiate the subject with optical signals and the optical detectors can detect signals from the subject. Analysis of the detected signals can yield information about the subject.

Abstract: A process and apparatus for determining the arterial and venous oxygenation of blood in vivo with improved precision. The optical properties of tissue are measured by determination of differential and total attenuations of light at a set of wavelengths. By choosing distinct wavelengths and using the measured attenuations, the influence of variables such as light scattering, absorption and other optical tissue properties is canceled out or minimized.

Abstract: A method and an optical system for evaluating the spatial distribution of the concentrations of components in tissue are disclosed. The novel detecting probe included in the optical system comprises plural optical fiber sets, each optical fiber set respectively comprises at least one source optical fiber and at least one detector optical fiber, the source optical fiber connects with the multi-wavelength light source, the source optical fiber delivers light from the multi-wavelength light source onto a tested tissue; and the angle between one optical fiber set and another optical fiber set is greater than 0° and less than and not equal to 180°. Through the optical system of the present invention, the spatial distribution of the concentrations of components such as water, hemoglobin, melanin, lipid, and collagen in the tested tissue can be derived by an equation (I) defined in the present specification.

Abstract: A tissue oximetry device utilizes at least three or at least four different wavelengths of light for collection of reflectance data where the different wavelengths are longer than 730 nanometers. The three or four wavelengths are utilized to generate a range of reflectance data suited for accurate determination of oxygenated hemoglobin and deoxygenated hemoglobin concentrations. The relatively long wavelengths decrease optical interference from certain dyes, particularly methylene blue and PVPI, which may be present on tissue being analyzed for viability and further enhance the generation of accurate reflectance data. The wavelengths are 760 nanometers, 810 nanometers, and 850 nanometers, or 760 nanometers, 810 nanometers, 850 nanometers, and 900 nanometers.

Abstract: A sleep apnea diagnostic system includes a housing that is configured to be attached to near the nose of a patient's face to sense physiological information of a patient. The housing includes sensors to sense the physiological information. The physiological information may be, for example, air flow through the nose or the mouth or both. The physiological information further may be, for example, blood volume. The sleep apnea diagnostic system includes at least one processor in the housing or external to the housing or both to analyze the physiological information to determine whether the patient has experienced irregular or abnormal respiratory activity and to detect respiratory effort. The analysis may be real time or delayed.

Abstract: According to the present invention, a method and apparatus for non-invasively determining the blood oxygen saturation level within a subject's tissue is provided. The method comprises the steps of: a) providing a spectrophotometric sensor operable to transmit light into the subject's tissue, and to sense the light; b) detecting light after passage through the subject's tissue using the sensor, and producing initial signal data from the light sensed; c) calibrating the sensor to that particular subject using the initial signal data, thereby accounting for the specific physical characteristics of the particular subject's tissue being sensed; and d) using the calibrated sensor to determine the blood oxygen parameter value within the subject's tissue.

Abstract: Systems and method for monitoring patient physiological data are presented herein. In one embodiment, a physiological sensor and a mobile computing device can be connected via a cable or cables, and a processing board can be connected between the sensor and the mobile computing device to conduct advanced signal processing on the data received from the sensor before the data is transmitted for display on the mobile computing device.

Abstract: The present disclosure provides various systems and methods for focusing electromagnetic radiation (EMR) within a diffusion medium, such as a turbid medium. A diffusion medium is irradiated with EMR. The EMR may be modulated by an acoustical wave focused on a focus volume within the diffusion medium. The EMR may be modulated by a beat frequency or other function of multiple focused acoustical waves. The EMR may be modulated at a harmonic of a fundamental frequency of one or more acoustical waves. A filter may filter the emerging EMR to remove all but specifically modulated EMR scattered from the focus volume. The modulated EMR may be focused and/or used for various purposes, including imaging. In some embodiments, the modulated EMR may be reflected and/or amplified by a phase conjugating mirror. Furthermore, in some embodiments, acoustical phase conjugation may be used to focus an acoustical wave on a focus volume.

Abstract: The present disclosure provides various systems and methods for focusing electromagnetic radiation (EMR) within a diffusion medium, such as a turbid medium. A diffusion medium is irradiated with EMR. The EMR may be modulated by an acoustical wave focused on a focus volume within the diffusion medium. The EMR may be modulated by a beat frequency or other function of multiple focused acoustical waves. The EMR may be modulated at a harmonic of a fundamental frequency of one or more acoustical waves. A filter may filter the emerging EMR to remove all but specifically modulated EMR scattered from the focus volume. The modulated EMR may be focused and/or used for various purposes, including imaging. In some embodiments, the modulated EMR may be reflected and/or amplified by a phase conjugating mirror. Furthermore, in some embodiments, acoustical phase conjugation may be used to focus an acoustical wave on a focus volume.

Abstract: Spectral absorption based non-invasive procedure for determination of blood constituents utilizing in vivo NIRS (Near-Infrared Spectrum) technology, which is the measurement of the near-infrared absorption spectrum within a region of the living human body for the purpose of identifying tissue and blood components and their concentrations and more particularly to novel applications and methodology for determining the optical response, measurements and calculations relating to the concentrations of individual chromophores in the bloodstream and particularly to the level of CO chromophores in the tissues of an animal or human being.

Abstract: A concentration measurement apparatus measures a temporal relative change amount (?cHb, ?O2Hb) of either or both of total hemoglobin concentration and oxygenated hemoglobin concentration in the head that vary due to repetition of chest compression, and includes a light incidence section making measurement light incident on the head, a light detection section detecting the measurement light propagated through the interior of the head and generating a detection signal in accordance with the intensity of the measurement light, and a CPU determining, based on the detection signal, the relative change amount (?cHb, ?O2Hb) and performing a filtering process of removing frequency components less than a predetermined frequency from frequency components contained in the relative change amount (?cHb, ?O2Hb).

Abstract: Methods and devices are provided for real time adjustment of noninvasively measured capillary hemoglobin concentration measures for a prediction of invasively measured hemoglobin concentration in large vessels and evaluating and modifying the state of interstitial hydration of an individual by the mVLT method. Implication of mVLT was refined by adding new diagnostic criteria and new variables, also expanding its noninvasive applicability. That opens application in the automated clinical decision support systems, semi-closed and closed loop infusion systems for optimisation of hydration, blood circulation and tissues perfusion, also optimizing blood transfusions.

Abstract: A compact perfusion scanner and method of characterizing tissue health status are disclosed that incorporate pressure sensing components in conjunction with the optical sensors to monitor the level of applied pressure on target tissue for precise skin/tissue blood perfusion measurements and oximetry. The systems and methods allow perfusion imaging and perfusion mapping (geometric and temporal), signal processing and pattern recognition, noise cancelling and data fusion of perfusion data, scanner position and pressure readings.

Abstract: A used photoacoustic apparatus includes: a light source capable of individually emitting light having a first wavelength at which absorption coefficients of oxyhemoglobin and deoxyhemoglobin are equal and light having a second wavelength; an acoustic detector that receives acoustic waves generated when the light having the first and second wavelengths is absorbed by an object; an absorption coefficient distribution generator that determines absorption coefficient distributions of an object interior; a blood vessel position determining unit that determines a blood vessel position from an absorption coefficient distribution corresponding to the first wavelength; an organism characteristics distribution calculator that determines an organism characteristics distribution from the absorption coefficient distributions; and a trimming unit that trims the organism characteristics distribution in accordance with the blood vessel position.

Abstract: An electronic endoscope has normal and high-sensitivity image sensors. In a special mode for imaging an oxygen saturation level of blood, one of the normal and high-sensitivity image sensors is selected in accordance with a reflected light amount of special illumination light. When the normal image sensor is selected, the normal image sensor captures an image under irradiation with the special illumination light and outputs a second normal-sensor image. When an average pixel value of the second normal-sensor image is less than a first sensor selection threshold value, the use of the high-sensitivity image sensor is started. When the high-sensitivity image sensor is selected, the high-sensitivity image sensor captures an image under irradiation with the special illumination light and outputs a high-sensitivity-sensor image. When the average pixel value of the high-sensitivity-sensor image is more than a second sensor selection threshold value, the use of the high-sensitivity image sensor is stopped.

Abstract: A system including a sensor and a device coupled to the sensor. The sensor is configured to detect in Animalia tissue (i) a first electromagnetic radiation extinction dominated by absorption of a first wavelength and (ii) a second electromagnetic radiation extinction dominated by scattering of a second wavelength. The device is configured to aid in diagnosing at least one of infiltration and extravasation in the Animalia tissue based on the first and second electromagnetic radiation extinctions detected by the sensor.

Abstract: A method for determining oxygen saturation includes emitting light from sources into tissue; detecting the light by detectors subsequent to reflection; and generating reflectance data based on detecting the light. The method includes determining a first subset of simulated reflectance curves from a set of simulated reflectance curves stored in a tissue oximetry device for a coarse grid; and fitting the reflectance data points to the first subset of simulated reflectance curves to determine a closest fitting one of the simulated reflectance curves. The method includes determining a second subset of simulated reflectance curves for a fine grid based on the closest fitting one of the simulated reflectance curves; determining a peak of absorption and reflection coefficients from the fine grid; and determining an absorption and a reflectance coefficient for the reflectance data points by performing a weighted average of the absorption coefficients and reflection coefficients from the peak.

Abstract: A system for optically measuring blood parameters including a light source and light transmitter for transmitting light to the blood, a light remitter for capturing remitted light, a spectrometer breaking the remitted light into its spectral components and a processor for comparing a morphologically distinct portion of the remitted light to a database of known morphologies. Each of the known morphologies corresponds to a measurement value at least one parameter, such as an analyte. Advantageously, the determined morphologies can uniquely correspond to two or more blood parameters, such as O2Hb and tHb, allowing simultaneous determination of the two parameters.

Abstract: The present invention, in one aspect, relates to a method for distinguishing between possible adenomatous and hyperplastic polyps using what :is referred to as “Early Increase in microvascular Blood Supply” (EIBS) that exists in tissues that are close to, but are not themselves, the abnormal tissue.

Abstract: The present disclosure describes embodiments of a patient monitoring system and methods that include the measure and display of hemoglobin statistics. In an embodiment, total hemoglobin trending is displayed over a period of time. Statistics can include frequency domain analysis, which may be unique for each patient monitored. The total hemoglobin trending and/or statistics can further be used to help control the treatment of a patient, such as being used to control IV administration.

Abstract: In one embodiment, measuring mitochondrial capacity includes performing arterial occlusions on a patient, measuring oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin within the patient's body during the occlusions, calculating a blood volume correction factor that accounts for a change in blood volume that occurs during the arterial occlusions, and applying the correction factor to the measured oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements to obtain correct oxygenated hemoglobin/myoglobin and deoxygenated hemoglobin/myoglobin measurements.

Abstract: A physiological parameter tracking system has a reference parameter calculator configured to provide a reference parameter responsive to a physiological signal input. A physiological measurement output is a physiological parameter derived from the physiological signal input during a favorable condition and an estimate of the physiological parameter according to the reference parameter during an unfavorable condition.

Abstract: Embodiments of devices, methods, and non-transitory computer readable media for monitoring a subject are presented. The monitoring device includes at least one sensor configured to monitor one or more physiological parameters of a subject and a processing unit operatively coupled to the sensor. The sensor comprises a plurality of radiation sources and detectors disposed on a flexible substrate in a designated physical arrangement. The processing unit is configured to dynamically configure an operational geometry of the sensor by controlling the intensity of one or more of the radiation sources and the gain of one or more of the detectors so as to satisfy at least one quality metric associated with one or more physiological parameters of the subject.

Abstract: A method for noninvasively measuring analyte levels includes using a non-imaging OCT-based system to scan a two-dimensional area of biological tissue and gather data continuously during the scanning. Structures within the tissue where measured-analyte-induced changes to the OCT data dominate over changes induced by other analytes are identified by focusing on highly localized regions of the data curve produced from the OCT scan which correspond to discontinuities in the OCT data curve. The data from these localized regions then can be related to measured analyte levels.

Abstract: The present invention pertains to a method and apparatus for total hemoglobin measurement. A modulated optical signal based on a digital code sequence is transmitted to human tissue. A temporal transfer characteristic is derived from the modulated optical signal. Total hemoglobin is determined based on the temporal transfer characteristic.

Abstract: A system and method for noninvasively determining the oxygenation of a tissue, for example, a muscle, in vivo uses optical methods to optically interrogate the tissue in both a visible wavelength range and a near infrared (NIR) wavelength range. The illuminating light is sculpted in intensity to approximately match the absorbance spectrum, for example, with the visible light having an intensity an order of magnitude greater than the light. Training data is obtained from healthy patients in both the visible and NIR ranges simultaneously and used to calculate muscle oxygenation.

Abstract: Provided is a method of calibrating a pulse oximeter, in which the effects caused by tissue of a subject can be taken into account. A detector output signal is measured when living tissue of the subject is present between emitters and the detector in a sensor. Nominal calibration and nominal calibration characteristics are read from a memory, whereupon values for the same nominal characteristics for the sensor on living tissue of the subject are established using the detector output signal. Then, changes in the nominal calibration characteristics induced by the living tissue are calculated and a subject-specific calibration is formed by correcting the nominal calibration with the changes. Finally, the hemoglobin fractions are solved using the corrected nominal calibration.

Abstract: A biological optical measurement instrument includes a single temperature sensor that detects a radiation temperature from a plurality of light emitting elements that emit light of a predetermined wavelength, and an absorption coefficient correcting unit that corrects an absorption coefficient value of a notable substance inside the object on the basis of the radiation temperature detected by the temperature sensor, referring to data indicating a correspondence relationship between a temperature obtained in advance for each emitted light of the plurality of light emitting elements and an absorption coefficient value that varies according to the temperature.

Abstract: Present embodiments are directed to a system and method capable of modulating light to at least one modulation frequency selected based on at least one blood parameter of a medium being monitored to generate photon density waves in a medium, detecting relative amplitude changes and phase shifts in the photon density waves, and determining at least one blood parameter related to scattering particles in the medium based on the phase shifts.

Abstract: A noninvasive blood component measuring device configured so as to resolve the variance of measuring results depend on the fixing position to the living body. Concretely, a non-invasive blood component measuring device comprising a light source section for illuminating a living body which includes a blood vessel, an imaging section for imaging the living body illuminated by the light source, and a controller is disclosed. The controller includes a memory under control of a processor.

Abstract: Methods for measuring the total hemoglobin of whole blood include measuring reflective light at multiple wavelengths within the visible spectrum, calculating light absorbance at each of the multiple wavelengths, performing a comparison in a change in like absorbance between the multiple wavelengths, and/or relating the comparison to total hemoglobin. A system for measuring total hemoglobin of whole blood may include at least one light source, a catheter, optical fibers, at least one photodetector, data processing circuitry, and/or a display unit.

Abstract: An apparatus and a program are provided which are capable of simultaneously measuring, evaluating, imaging and displaying the biological function of sites with different biological functions, such as the brain and the muscle, different parts of the brain or different muscle locations, using near-infrared spectroscopy. In an apparatus for evaluating biological function K, physiological indices, including parameters derived from changes in deoxyhemoglobin concentration and changes in oxyhemoglobin concentration, are calculated by a calculating part of a controller. To measure simultaneously, evaluate, image and display the biological functions of sites with different biological function, such as the brain and the muscle, different parts of the brain or different muscle locations, these physiological indices from different sites of the living body are adjusted in such a way that they can be compared with each other by the calculating part and displayed by a display part.

Abstract: A medical device for monitoring a patient condition includes a sensor capable of being advanced transvascularly to be positioned along a volume of tissue, the sensor including a first combination of a light source and a light detector to emit light into a volume of tissue and to detect light scattered by the volume of tissue and to generate a first output signal corresponding to an intensity of the detected light. A control module is coupled to the light source to control the light source to emit light at least four spaced-apart light wavelengths, and a monitoring module is coupled to the light detector to receive the output signal and compute a measure of tissue oxygenation using the light detector output signal.

Abstract: The invention is directed to methods and systems of hyperspectral and multispectral imaging of medical tissues. In particular, the invention is directed to new devices, tools and processes for the detection and evaluation of diseases and disorders such as, but not limited to diabetes and peripheral vascular disease and cancer, that incorporate hyperspectral or multispectral imaging.

Abstract: Systems and methods for estimating a saturation level of oxygen in hemoglobin (SpO2) are provided. In some aspects, a system includes a detector module configured to receive an oximeter output signal indicative of light absorption in a patient. The oximeter output signal alternates between infrared light components and red light components, and includes a first portion obtained at least partly during switching from at least one of the infrared components to at least one of the red components. The oximeter output signal also includes a second portion obtained at least partly during switching from at least one of the red components to at least one of the infrared components. The system also includes a processing module configured to estimate an SpO2 of the patient as a ratio between (i) a time derivative of the first portion and (ii) a time derivative of the second portion.

Abstract: A method and device for processing mammalian adipose tissue such that the vascular rich fraction is separated from the vascular poor fraction, Mammalian adipose tissue in the form of morselated surgical biopsies and/or lipoaspirate from liposuction is placed within a novel syringe attached to a detection device measuring either color, light saturation, infra-red light, heme, iron or oxygen saturation. This process involves no label and minimal manipulation and handling of the tissue. This process and device may also be used intra-operatively under sterile conditions for immediate use within the same individual receiving liposuction or surgery.

Abstract: Provided is a holder which comprises at least two probe mount portions into which a light-transmitting probe for emitting light from the tip thereof or a light-receiving probe for receiving light through the tip thereof is inserted from above and is to be put on the head of a subject, the holder being characterized by further comprising: a linear backbone portion that extends in a first direction that is perpendicular to the above-described direction from above; and at least two linear branch portions that extend in a second direction that is perpendicular to the above-described direction from above and is different from the first direction, wherein the lower end portions of the probe mount portions protrude from the lower surface of the backbone portion or a branch portion and are tapered.

Abstract: A method for using a medical device comprising an optical sensor to measure calibrated oxygen saturation in a body tissue uses a standard spectral response of blood established for multiple of oxygen saturations and a standard spectral response of a reference material. The standard responses are established using a spectrometer. The spectral power output of the optical sensor is measured using a spectrometer. The optical sensor output signal response to the reference material is obtained. A processor computes a device-specific calibration curve for the medical device using the measured spectral power output and the standard spectral response of blood and computes an optical gain using the standard spectral response of the reference material and the measured spectral power output of the optical sensor. The device-specific calibration curve and optical gain of the optical sensor are stored in a memory of the medical device.

Abstract: Systems and methods of frequency-domain photoacoustic imaging are provided utilizing an ultrasonic phased array probe and intensity modulated optical excitation with coding to improve signal-to-noise ratio. Embodiments employ frequency-domain photoacoustic imaging methodologies such as the photoacoustic radar, coupled with a multi-element ultrasonic sensor array to deliver spatially-resolved correlation images of photoacoustic sources, which may be employed to image optical heterogeneities within tissue-like scattering media.

Abstract: Optical sensor devices, image processing devices, methods and computer readable code computer-readable storage media for detecting biophysical parameters, chemical concentrations, chemical saturations and blood count. In some embodiments, the image processing device receives a live still or video electronic image. Exemplary physiological parameters include but are not limited to a pulse rate, blood pressure, glucose, stroke volume of internal or external tissue (e.g. skin). A biophysical or physiological property is not limited to a cardiovascular or liver or the kidneys or to a cardiovascular disorder or to a pulmonary disorder. Exemplary chemical concentrations or saturation includes but not limited to a pH level, a glucose level, a urea nitrogen level, a CO2 concentration or saturation, or a oxygen concentration or saturation. In some embodiments the parameters are detected from a food or a beverage such as an alcohol, a dairy product, wine, a baked good, a fruit or a vegetable.

Abstract: In medical imaging, a fiducial marker facilitates tissue image correlation that allows for image analysis, normalization and correction of the optical exposure and spectral and spatial distribution in order to compensate for the surface reflections, sub surface tissue interactions and spatial orientation of the excitation and imaging axes to the subject tissue. Using a cross comparison, clinicians can model tissue image data in different forms in order to reference and compare data from various spectral components and or from different images. This may enhance human interpretation between images including the variations between images even when the spectral, spatial and optical conditions or the image resolution or sensitivity are compromised. Such may be used to assess cosmetic, moisturizing, therapeutic materials and treatments.

Abstract: The present invention generally relates to a non-invasive biosensor device configured to measure physiological parameters of a subject. In one aspect, a method of determining a training threshold of a subject is provided. The method includes the step of detecting an oxygenation parameter of a tissue of the subject using Near InfraRed Spectroscopy (NIRS). The method further includes the step of processing the oxygenation parameter. Additionally, the method includes the step of determining the training threshold of the subject using the result of the processing. In another aspect, a biosensor device for determining a lactate threshold of a subject during exercise is provided. In a further aspect, a biosensor device for measuring parameters of a subject during exercise is provided.

Abstract: Disclosed is a functional NIRS imaging system including an elastomeric cap, a set of transmit optical fibers and a set of receive optical fibers terminating on the inside surface of the elastomeric cap. A pair of light sources combines to produce a collimated light beam at two wavelengths. An optical modulation system, converts the light beam into a plurality of probe light beams, modulates the plurality of probe light beams and directs each probe light beam into a transmit fiber. An optical detection system accepts scattered photons from subcutaneous tissue underneath the elastomeric cap as a plurality of collected light beams and converts them into a time series of electronic images, stores the electronic images into the memory and processes the electronic images using. The system displays the resulting image on a display as a hemoglobin oxygen saturation map.

Abstract: The invention relates to a method for non-invasive determination of oxygen saturation of blood within a deep vascular structure of a human patient comprising locating on skin of the patient in a vicinity of the deep vascular structure of interest emitter and receiver elements of a light oximeter device, wherein optimal location of said elements is achieved through matching of a plethysmography trace obtained from the oximeter device to known plethysmography characteristics of the deep vascular structure of interest, and wherein oxygen saturation is determined from a ratio of light absorbed at different wavelengths by haemoglobin in the blood within the vascular structure of interest. The invention also relates to modified oximetry devices capable of carrying out the method.

Abstract: Systems and methods for determining a physiological parameter in a patient are provided. In certain embodiments, a system can include an analyte detection system configured to measure first analyte data in a fluid sample received from a patient, a medical sensor configured to measure second analyte data in the patient, and a processor configured to receive the first analyte data and the second analyte data and to determine a physiological parameter based at least in part on the first analyte data and the second analyte data. In certain such embodiments, the medical sensor may be a pulse oximeter, and the physiological parameter may include a cardiovascular parameter including, for example, cardiac output.

Abstract: The apparatus for evaluating biological function of the present invention has living body probes 1, a behavioral information measuring part 2 and an apparatus body 3, and it utilizes near-infrared spectroscopy to evaluate biological function; apparatus body 3 has a controller 8 for calculating (based on light information from living body probes 1) a variety of parameters derived from two-dimensional diagrams showing relationships between changes in oxyhemoglobin and changes in deoxyhemoglobin and two-dimensional diagrams showing relationships between absolute amounts of oxyhemoglobin and absolute amounts of deoxyhemoglobin, a behavioral information input part for entering behavioral information measured by means of behavioral information measuring part 12, and a display part 10 for performing various types of image displays based on various parameters calculated by means of controller 8 and/or behavioral information entered in the behavioral information input part.

Abstract: A parameter affecting the absorptivity or the concentration of blood in tissue is measured using a semiconductor light source (7) and a light detector (8). The semiconductor light source (7) is operated at several operating conditions, at which it has different temperatures and therefore different emission spectra. In particular, the operating conditions correspond to different time intervals after switching the light source (7) on, while the light source (7) has not yet reached thermal equilibrium. This allows to perform a spectroscopic measurement using one light source only, which increases accuracy and reduces device cost.

Abstract: Methods and apparatus for video rate or near video rate quantitative imaging of tissue physiological and morphological properties from visible/NIR light spectral images obtain rapid multi-spectral reflectance images by illuminating with a series of spectra containing multiple narrow wavelength bands. An iterative light-transport based inversion algorithm may be applied for correcting the intensity of the spectral images from the geometry/coupling effect as well as from the scattering amplitude distortions. The method can produce video rate absorption as well as scattering spectral images that can be further analyzed very rapidly, using matrix-based rapid inversion algorithms to produce more detailed quantitative images containing information relevant to tissue physiology and morphology.

Abstract: An apparatus for determining an optical property of a set of cells is described. The apparatus may include a light source for providing a light signal, a light-conditioning unit configured to condition the light signal, and a diffractive structure. The diffractive structure may be configured to receive the conditioned light signal and produce diffracted light having plasmon-resonance properties and an angular spectrum. The angular spectrum may correspond to the set of cells when the set of cells are within a threshold distance from the diffractive structure. The apparatus further includes a light-collecting unit for collecting the diffracted light.

Abstract: A medical device for monitoring a patient condition includes a first combination of a light source and a light detector to emit light into a volume of tissue, detect light scattered by the volume of tissue, and provide a first output signal corresponding to an intensity of the detected light. A control module is coupled to the light source to control the light source to emit light at least four spaced-apart light wavelengths, and a monitoring module is coupled to the light detector to receive the output signal, compute a measure of tissue oxygenation in response to the light detector output signal, and detect tissue hypoxia using the measure of tissue oxygenation.