System and method for noninvasively measuring blood alcohol concentration using light
Inventors
Assignees
Publication Number
US-12109040-B2
Publication Date
2024-10-08
Expiration Date
2040-04-10
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Abstract
A system for noninvasively measuring blood alcohol concentration using light includes one or more emitters each configured to emit light in the near infrared or infrared light spectrum at one or more wavelengths that respond to varied chromophore concentrations of ethanol and water in blood of a human subject. One or more detectors is configured to detect light emitted at the one or more wavelengths and output a representation of a photoplethysmography (PPG) waveform for one or more of the one or more wavelengths. A processing subsystem is coupled to the one or more emitters and the one or more detectors. The processing subsystem is configured to determine a measure of an amplitude of the representation of the PPG waveform for each of the one or more wavelengths and determine the blood alcohol concentration by referencing the measured amplitude for each of the one or more wavelengths to a molar absorptivity plot which indicates a measure of the absorption or scattering at alcohol and water solutions ranging between a solution of 100% alcohol and a solution of 100% water.
Core Innovation
The invention relates to a system and method for noninvasively measuring blood alcohol concentration (BAC) using light, particularly in the near infrared or infrared light spectrum. The system includes one or more emitters configured to emit light at specific wavelengths responsive to varied chromophore concentrations of ethanol and water in the blood of a human subject. One or more detectors detect the emitted light at these wavelengths and output a photoplethysmography (PPG) waveform representation for one or more of these wavelengths.
A processing subsystem is coupled to the emitters and detectors and is configured to determine a measure of an amplitude of the PPG waveform representation for each wavelength. The blood alcohol concentration is then determined by referencing the measured amplitude for each wavelength to a molar absorptivity plot which indicates absorption or scattering for solutions ranging from 100% alcohol to 100% water. The system may operate by transmission or scattering of light through or within tissue, and includes features to enhance accuracy, such as referencing wavelengths where water and alcohol absorb or scatter similarly for calibration.
The problem addressed is the lack of an accurate, compact, wearable system to continuously and noninvasively measure BAC. Conventional near infrared spectroscopy systems for BAC measurement are typically large, bulky, and table-top, using broad spectra. There is a need for a small, compact wearable device to allow clinicians and individuals to monitor BAC discreetly and in real time, improving clinical understanding and personal safety related to alcohol consumption.
Claims Coverage
The patent claims include 2 independent claims covering a system and a method for noninvasively measuring blood alcohol concentration using light. The claims focus on the configuration of emitters, detectors, processing subsystems, and associated functionalities to determine BAC accurately.
Emitter configuration including wavelength intersection
The system uses one or more emitters configured to emit light in the near infrared or infrared spectrum at wavelengths responsive to varied chromophore concentrations of ethanol and water, including at least one wavelength where absorptivity or scattered reflectance spectra of water and alcohol intersect to improve measurement accuracy.
Detection and PPG waveform generation
The system includes one or more detectors configured to detect light at the specified wavelengths and output a representation of a photoplethysmography (PPG) waveform for one or more wavelengths.
Processing subsystem control and BAC determination
The processing subsystem rapidly and sequentially turns on and off emitters, determines a measure of amplitude of the PPG waveform representations, and determines blood alcohol concentration by referencing the measured amplitudes to a molar absorptivity plot. It also references wavelengths where water and alcohol concentrations ratio is the same to enhance accuracy.
Averaging determined BAC
The processing subsystem is further configured to average the determined blood alcohol concentration across wavelengths to enhance measurement accuracy.
Selection of wavelengths based on absorptivity or molar absorptivity
The light emitted by emitters and detected by detectors is determined by absorptivity or scattered reflectance spectra of water, alcohol, and/or molar alcohol absorptivity plots.
PPG waveform amplitude measurement methods
The processing subsystem determines amplitude of the PPG waveform by one or more of: difference between maximum and minimum PPG values from dynamic portions, root mean square (RMS), maximum PPG peak, minimum PPG peak, or root sum of squares (RSS).
Wearable device configuration
The system is configured as a wearable device, with detectors, emitters, processing subsystem, memory, and power supply having small compact sizes enclosed in a wearable housing.
Light transmission or scattering through tissue
The emitters may emit light transmitted through tissue and detected on the opposite side, or scattered within tissue with detectors on the same side as emitters.
These inventive features collectively provide a compact, wearable system and method that leverage specific light wavelengths and PPG waveform analysis referenced to molar absorptivity plots, enabling accurate and continuous noninvasive measurement of blood alcohol concentration.
Stated Advantages
High accuracy BAC measurements within minutes of consumption.
High temporal resolution to correlate BAC with physiological and psychological responses during clinical studies.
Very small and compact size allows integration into commercially accepted wearable devices.
Improved user compliance through discreet, passive measurements.
Long hardware lifespan with no moving or consumable components.
Enables users to passively and accurately monitor alcohol consumption for personal reasons.
Aids research to better understand correlations between alcohol consumption and overall health.
Provides clinicians access to high temporal resolution data to understand short term and long term alcohol consumption impacts.
Documented Applications
Wearable device for continuous, noninvasive blood alcohol concentration monitoring by individuals for social, safety, and rehabilitation purposes.
Clinical setting use to monitor the impact of short term and long term alcohol consumption on physiological, psychological, and social wellness.
Research tool to correlate BAC measurements to physiological and psychological responses during clinical studies.
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