Abstract: Estimation of a characteristic of a user's physiological signals can be improved using one or more calibration relationships that may be dependent on a characteristic of the optical sensor. For example, different calibration relationships can be used that are dependent on a spatial characteristic and/or that are dependent on a wavelength characteristic of the light emitting component(s) of the respective emitter of a channel. In some examples, a unique calibration relationship can be used for each channel. In some examples, a common calibration relationship can be used for multiple channels with shared distance and/or wavelength characteristics. Utilizing distance-dependent and/or wavelength-dependent calibration relationships can improve robustness of pulse oximetry measurements.

Abstract: Robust estimation of a characteristic of a user's physiological signals can be achieved by filtering or classifying samples. Rather than estimating the characteristic of the user's physiological signals based on each sample at a first wavelength and a second wavelength, a robust system and method can, in some examples, estimate the characteristic using samples at the first wavelength and the second wavelength that meet one or more criteria and filter out samples that fail to meet the one or more criteria. In some examples, the system and method can weight samples based on the one or more criteria, and estimate the characteristic using the weighted samples. Samples failing to meet the one or more criteria can be given less weight or no weight in the estimation. The one or more criteria can include a criterion based on at least the physiological signal at a third wavelength.

Abstract: A wearable device includes a housing; a wrist band attached to the housing; first and second emitters positioned within the housing and configured to respectively emit, through a back of the housing, a first beam of electromagnetic radiation having a first infrared (IR) wavelength and a second beam of electromagnetic radiation having a second IR wavelength. The second IR wavelength is different from the first IR wavelength. The wearable device also includes a photodetector positioned within the housing and filtered to detect a set of electromagnetic radiation wavelengths including the first IR wavelength and the second IR wavelength; and a matter differentiation circuit configured to indicate, at least partly in response to signals indicating amounts of the first IR wavelength and the second IR wavelength received by the photodetector, whether the back of the housing is likely proximate to human tissue.

Abstract: A wearable device includes a housing; a wrist band attached to the housing; first and second emitters positioned within the housing and configured to respectively emit, through a back of the housing, a first beam of electromagnetic radiation having a first infrared (IR) wavelength and a second beam of electromagnetic radiation having a second IR wavelength. The second IR wavelength is different from the first IR wavelength. The wearable device also includes a photodetector positioned within the housing and filtered to detect a set of electromagnetic radiation wavelengths including the first IR wavelength and the second IR wavelength; and a matter differentiation circuit configured to indicate, at least partly in response to signals indicating amounts of the first IR wavelength and the second IR wavelength received by the photodetector, whether the back of the housing is likely proximate to human tissue.

Abstract: A wearable device is described. The wearable device includes a housing having a back cover, and an optical mask on first portions of the back cover. The back cover includes a set of windows, with a first subset of windows in the set of windows being defined by an absence of the optical mask on second portions of the back cover, and a second subset of windows in the set of windows being inset in a set of openings in the back cover. An optical barrier surrounds each window in the second subset of windows. A set of light emitters is configured to emit light through at least some of the windows in the set of windows. A set of light detectors is configured to receive light through at least some of the windows in the set of windows.

Abstract: Estimation of a characteristic of a user's physiological signals can be improved using one or more calibration relationships that may be dependent on a characteristic of the optical sensor. For example, different calibration relationships can be used that are dependent on a spatial characteristic and/or that are dependent on a wavelength characteristic of the light emitting component(s) of the respective emitter of a channel. In some examples, a unique calibration relationship can be used for each channel. In some examples, a common calibration relationship can be used for multiple channels with shared distance and/or wavelength characteristics. Utilizing distance-dependent and/or wavelength-dependent calibration relationships can improve robustness of pulse oximetry measurements.

Abstract: A wearable device is described. The wearable device includes a housing having a back cover, and an optical mask on first portions of the back cover. The back cover includes a set of windows, with a first subset of windows in the set of windows being defined by an absence of the optical mask on second portions of the back cover, and a second subset of windows in the set of windows being inset in a set of openings in the back cover. An optical barrier surrounds each window in the second subset of windows. A set of light emitters is configured to emit light through at least some of the windows in the set of windows. A set of light detectors is configured to receive light through at least some of the windows in the set of windows.

Abstract: Robust estimation of a characteristic of a user's physiological signals can be achieved by filtering or classifying samples. Rather than estimating the characteristic of the user's physiological signals based on each sample at a first wavelength and a second wavelength, a robust system and method can, in some examples, estimate the characteristic using samples at the first wavelength and the second wavelength that meet one or more criteria and filter out samples that fail to meet the one or more criteria. In some examples, the system and method can weight samples based on the one or more criteria, and estimate the characteristic using the weighted samples. Samples failing to meet the one or more criteria can be given less weight or no weight in the estimation. The one or more criteria can include a criterion based on at least the physiological signal at a third wavelength.

Abstract: Robust estimation of a characteristic of a user's physiological signals can be achieved by filtering or classifying samples. Rather than estimating the characteristic of the user's physiological signals based on each sample at a first wavelength and a second wavelength, a robust system and method can, in some examples, estimate the characteristic using samples at the first wavelength and the second wavelength that meet one or more criteria and filter out samples that fail to meet the one or more criteria. In some examples, the system and method can weight samples based on the one or more criteria, and estimate the characteristic using the weighted samples. Samples failing to meet the one or more criteria can be given less weight or no weight in the estimation. The one or more criteria can include a criterion based on at least the physiological signal at a third wavelength.

Abstract: A wearable device is described. The wearable device includes a housing having a back cover, and an optical mask on first portions of the back cover. The back cover includes a set of windows, with a first subset of windows in the set of windows being defined by an absence of the optical mask on second portions of the back cover, and a second subset of windows in the set of windows being inset in a set of openings in the back cover. An optical barrier surrounds each window in the second subset of windows. A set of light emitters is configured to emit light through at least some of the windows in the set of windows. A set of light detectors is configured to receive light through at least some of the windows in the set of windows.

Abstract: The present invention provides a method for stabilizing the gain of an avalanche photodiode in a medical laser diode receiver. This method is characterized by comprising: (a) a step in which a high-voltage generation unit generates a high-voltage bias and applies same to an avalanche photodiode; (b) a step in which a temperature sensor senses the temperature of the avalanche photodiode; (c) a step in which a control unit controls a variable resistance value, which varies the voltage of the high-voltage bias, according to the value of the sensed temperature; (d) a step in which to detect if an output voltage signal is equivalent to the intensity of light received by the avalanche photodiode; and (e) a step in which a storage unit matches the sensed temperature value with the controlled variable resistance value and stores same. The present invention allows a reduction in production costs and also a significant reduction in the size of a measuring device itself.

Abstract: The present invention provides a method for stabilizing the gain of an avalanche photodiode in a medical laser diode receiver. This method is characterized by comprising: (a) a step in which a high-voltage generation unit generates a high-voltage bias and applies same to an avalanche photodiode; (b) a step in which a temperature sensor senses the temperature of the avalanche photodiode; (c) a step in which a control unit controls a variable resistance value, which varies the voltage of the high-voltage bias, according to the value of the sensed temperature; (d) a step in which to detect if an output voltage signal is equivalent to the intensity of light received by the avalanche photodiode; and (e) a step in which a storage unit matches the sensed temperature value with the controlled variable resistance value and stores same. The present invention allows a reduction in production costs and also a significant reduction in the size of a measuring device itself.

Abstract: A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain and steady-state reflectance methods. Most of the wavelength coverage is provided by a white-light steady-state measurement, whereas the frequency-domain data are acquired at a few selected wavelengths. Coefficients of absorption and reduced scattering derived from the frequency-domain data are used to calibrate the intensity of the steady-state measurements and to determine the reduced scattering coefficient at all wavelengths in the spectral window of interest. The absorption coefficient spectrum is determined by comparing the steady-state reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined frequency-domain and steady-state technique, agree well with expected reference values.

Abstract: A method of optically analyzing tissue in vivo in an individual to obtain a unique spectrum for the tissue of the individual includes the steps of optically measuring the tissue of the individual using broadband diffuse optical spectroscopy (DOS) to measure a normalized tissue water spectrum of the individual or noninvasively optically line scanning a tissue site on the individual at a plurality of points, then determining spectral differences between the normalized tissue water spectrum and a pure water spectrum at each point of a line scan, generating a bound water index (BWI) corresponding to the spectral differences, and identifying a tissue state corresponding to the scanned tissue based on the BWI.

Abstract: A device and method utilizes a broadband diffuse optical spectroscopy (DOS) system to dynamically calculate the concentrations of multiple chromophores in vivo using a non-invasive probe. The device and method permit dynamic monitoring of multiple in vivo tissue chromophores non-invasively with sensitivities necessary for effective therapeutic monitoring. The device includes a probe containing first and second source optical fibers as well as first and second detector optical fibers. The probe is placed adjacent to a sample of interest and detects reflected light which is passed to a proximally located detector and spectrometer. The concentrations of multiple chromophores are determined in real time. In a preferred embodiment, the multiple tissue chromophores include at least two of methemoglobin (MetHb), deoxyhemoglobin (Hb-R), oxyhemoglobin (Hb-O2), water (H2O), and methylene blue (MB).

Abstract: A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain and steady-state reflectance methods. Most of the wavelength coverage is provided by a white-light steady-state measurement, whereas the frequency-domain data are acquired at a few selected wavelengths. Coefficients of absorption and reduced scattering derived from the frequency-domain data are used to calibrate the intensity of the steady-state measurements and to determine the reduced scattering coefficient at all wavelengths in the spectral window of interest. The absorption coefficient spectrum is determined by comparing the steady-state reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined frequency-domain and steady-state technique, agree well with expected reference values.