System and method for noninvasively measuring blood alcohol concentration using light
Inventors
Assignees
Publication Number
US-11013460-B2
Publication Date
2021-05-25
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 is a system and method for noninvasively measuring blood alcohol concentration (BAC) using light. It uses one or more emitters configured to emit light in the near infrared or infrared light spectrum at wavelengths that respond to varied chromophore concentrations of ethanol and water in the blood of a human subject. One or more detectors detect light at these wavelengths and output a representation of a photoplethysmography (PPG) waveform for one or more wavelengths.
A processing subsystem is coupled to the emitters and detectors to determine the amplitude of the PPG waveform 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 measures at alcohol and water solutions ranging from 100% alcohol to 100% water. The system can be configured as a small, compact wearable device allowing clinicians and individuals to continuously and noninvasively monitor BAC for health and safety.
The problem being solved is the need for a convenient, accurate, and compact system to noninvasively measure BAC. Existing methods, such as breath analysis and conventional near infrared spectroscopy, are either cumbersome, bulky, or not suited for wearable continuous monitoring. Particularly lacking are methods suitable for clinical and personal use to understand the short term and long term effects of alcohol consumption in a discreet, precise, and high temporal resolution manner.
Claims Coverage
The patent includes three independent claims covering both a system and a method for noninvasively measuring blood alcohol concentration using light. The claims focus on the configuration of emitters, detectors, and processing to determine BAC based on PPG waveform amplitude measurements referenced to molar absorptivity plots.
Measurement of BAC using light at selected wavelengths responding to ethanol and water concentrations
The system includes one or more emitters emitting near infrared or infrared light at wavelengths that respond to varied chromophore concentrations of ethanol and water in the blood, one or more detectors that output a representation of a photoplethysmography (PPG) waveform for the wavelengths, and a processing subsystem that determines the amplitude of the PPG waveform and determines BAC by referencing amplitudes to a molar absorptivity plot.
Processing subsystem averaging and amplitude determination techniques
The processing subsystem can average BAC measurements across wavelengths to improve accuracy. It determines amplitude of PPG waveforms using methods including difference between maximum and minimum PPG values, root mean square (RMS), maximum peak, minimum peak, and root sum of squares (RSS) from the dynamic portion of the PPG waveform.
System configured as wearable for transmission or scattering light detection
The system may be configured as a wearable device with emitters and detectors designed to either measure transmitted light through tissue with emitters and detectors on opposite sides or detect reflected scattered light with both on the same side of the tissue section.
Method for noninvasively measuring BAC using the detection and referencing of PPG waveform amplitudes
The method includes emitting light at wavelengths responsive to ethanol and water in blood, detecting light, outputting PPG waveforms, determining the amplitude of the PPG waveforms, and determining BAC by referencing amplitudes to molar absorptivity plots ranging between solutions of 100% alcohol and 100% water, including averaging measurements to improve accuracy.
Together, the claims cover a novel configuration of emitters, detectors, and processing steps to noninvasively and accurately measure blood alcohol concentration via analysis of PPG waveforms at selected near-infrared or infrared wavelengths, supporting wearable applications and multiple amplitude measurement techniques.
Stated Advantages
The system enables high accuracy BAC measurements within minutes after alcohol consumption.
It provides high temporal resolution to correlate BAC to physiological and/or psychological responses during clinical studies.
The system has a very small and compact size allowing integration into commercially accepted wearable devices.
It improves user compliance through discreet and continuous monitoring.
The system has a long hardware lifespan with no moving or consumable components.
It provides users with the ability to passively and accurately monitor their alcohol consumption for personal and clinical purposes.
It aids the research community to better understand correlations between alcohol consumption and overall health.
It significantly improves clinician access to high temporally resolute data to better understand short term and long term impacts of alcohol consumption.
Documented Applications
Continuous, noninvasive blood alcohol concentration monitoring for individuals and clinicians.
Integration into wearable devices such as fitness trackers or smartwatches.
Monitoring driver intoxication for safety purposes.
Clinical studies to correlate BAC with physiological and psychological responses.
Personal monitoring of alcohol consumption for rehabilitation, social, and safety reasons.
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