Patent Description:
This invention relates to system for noninvasively measuring blood alcohol concentration using light.

There has been significant research concerning the benefits and detriments of consuming alcoholic beverages. Blood alcohol concentration (BAC) has long been linked to a reduction in driver safety and competency leading to a higher frequency of automobile accidents. Studies have shown that the slightest amount of alcohol in a driver's system (e.g., about <NUM>%) can significantly increase the severity of automobile accidents. See <NPL>).

Alcohol consumption and BAC may also have a noticeable physiological effect on the human body. One well known medical condition which may be caused by alcohol abuse is cirrhosis of the liver where the death rate correlates with the volume of daily alcohol consumption. It is also well known that excessive alcohol consumption may also result in cognitive decline. Excessive alcohol consumption may also increase the death rate associated with vehicle accidents which result from impaired decision making and coordination. Excessive alcohol consumption may also cause cancer of the mouth, esophagus, pharynx, larynx, liver, and colorectal region.

The studies discussed above have also found benefits of consuming alcoholic beverages in moderation. One benefit found was a reduction in the death rate of major cardiovascular conditions, possibly due to a reduction in blood pressure brought on by alcohol consumption. Studies have also shown a few drinks of an alcohol beverage per day may be beneficial but becomes increasingly detrimental as more drinks are consumed.

Similarly, researchers have found that high alcohol consumption (e.g., about <NUM> grams of alcohol per day) may increase the risk of stroke and reducing alcohol consumption (e.g., about <NUM> grams per day) may reduce the risk of stroke. See <NPL> of the.

American Medical Association, February <NUM>. <NUM>, Vol <NUM>, No, <NUM>. Many other diseases and conditions follow may follow this trend.

As is well known, responsible use of alcohol consumption can easily turn into abuse. In response, communities, law enforcement agencies, and researchers have a vested interest in the ability to monitor BAC to determine the state of inebriation and to understand the side effects and consequences of alcohol consumption. As physiological monitoring devices become commonplace for individual users, e.g., wearable smart devices, such as the Fitbit®, the Apple® watch, and the like, this trend will likely carry to individuals desiring to monitor their own BAC for social, safety, and rehabilitation purposes.

For nearly a century, since the estimation of blood alcohol content through breath Analysis was first discovered, there has been a need for a convenient and accurate way to measure BAC Conventional systems and methods which use near infrared spectroscopy to evaluate BAC are typically large, bulky, cumbersome systems typically only available as table-top systems and use broad near-infrared spectrum, e. g, about <NUM> to about <NUM>. Driven by a desire to reduce the impact driving fatalities related to alcohol intoxication, there has been significant strides in creating various conventional technologies to measure BAC of drivers.

<CIT> and <CIT> disclose systems for non-invasively measuring blood alcohol concentration.

However, to date, there has been little focus or effort on providing a wearable system and method to continuously and noninvasively monitor BAC in an accurate, precise, and discreet manner. This is especially true in a clinical setting where the full impact of short term and long term alcohol consumption and use on physiological, psychological and social wellness is understood only at a high level.

Thus, there is a need for a small, compact system and method for noninvasively and accurately measuring BAC that can be configured as a wearable device on a user to allow clinicians to fully understand the impact of short term and long-term alcohol consumption and use on overall health and for individuals to accurately and immediately monitor their own BAC.

In one aspect, a system for noninvasively measuring blood alcohol concentration using light is featured. The system 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, said representation comprising a static portion and a dynamic portion.

A processing subsystem coupled to the one or more emitters and the one or more detectors is configured to determine a measure of an amplitude of the dynamic portion 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 <NUM>% alcohol and a solution of <NUM>% water.

In one embodiment, the processing subsystem may be further configured to average the determined blood alcohol concentration at each of the one or more wavelengths to enhance the accuracy of the measured blood alcohol concentration. The light emitted by the one or more emitters at the one or more wavelengths may be determined by one or more of: an absorptivity or scattered reflectance light spectrum of water, an absorptivity or scattered reflectance light spectrum of alcohol, and/or the molar alcohol absorptivity plot. The one or more detectors may be configured to detect light emitted at one or more wavelengths determined by the one or more of: the absorptivity or scattered reflectance light spectrum of water, the absorptivity or scattered reflectance light spectrum of alcohol, and/or the molar alcohol absorptivity plot. The processing subsystem may be configured to rapidly and sequentially turn on and turn off one or more of the one or more emitters emitting light at the one or more wavelengths. The processing subsystem may be configured to turn on one of more of the one or more emitters to continuously emit the light at the one or more wavelengths. The one or more detectors may be configured to provide the representation of the PPG waveform for each of the one or more wavelengths as an analog representation. The one or more detectors may be configured to provide the representation of the PPG waveform for each of the one or more wavelengths as a digital representation. The processing subsystem may be configured to determine the measure of the amplitude of the representation of the PPG waveform for each of the one or more wavelengths by one or more of: determining a difference between a maximum PPG value and a minimum PPG value from a dynamic portion of the PPG waveform, determining a route mean square (RMS) value from the dynamic portion of the PPG waveform, determining a maximum PPG peak value from the dynamic portion of the PPG waveform, determining a minimum PPG peak value from the dynamic portion of the PPG waveform, and/or determining a root sum of squares (RSS) from the dynamic portion of the PPG waveform. The system may be configured as a wearable device on the human subject. The one or more detectors, the one or more of emitters, the processing subsystem, a memory, and a power supply each may have a small compact size and may be enclosed in a wearable housing. The emitted light provided by the one or emitters may be transmitted through tissue of the human subject. The one or more detectors may be configured to detect the transmitted light at the one or more wavelengths and output the representation of a photoplethysmography (PPG) waveform for one or more of the one or more wavelengths. At least one of the one or more emitters may be located on one side of an area of the human subject and at least one of the one or more detectors may be located on an opposite side of the area. The emitted light provided by the one or emitters may be scattered in tissue of the human subject. The one or more detectors may be configured to detect reflected scattered light at the one or more wavelengths and output the representation of a photoplethysmography (PPG) waveform for one or more of the one or more wavelengths. At least one of the one of the one or more emitters may be located on a same side of an area of the human subject as at least one of the one or more detectors.

In another aspect not covered by the present invention, a method for noninvasively measuring blood alcohol concentration using light is featured. The method includes emitting light in the near-infrared or infrared spectrum at one or more wavelengths that respond to varied chromophore concentrations of ethanol and water in blood of a human subject. The method includes detecting light emitted at the one or more wavelengths. The method includes outputting a representation of a photoplethysmography (PPG) waveform for one or more of the one or more wavelengths. The method includes determining a measure of an amplitude of the representation of the PPG waveform for each of the one or more wavelengths, and determining the 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 <NUM>% alcohol and a solution of <NUM>% water.

In one embodiment, the method may include averaging the determined blood alcohol concentration at each of the one or more wavelengths to enhance accuracy of the measured blood alcohol concentration. The light emitted at the one or more wavelengths may be determined by one or more of: an absorptivity or scattered reflectance light spectrum of water, an absorptivity or scattered reflectance light spectrum of alcohol, and/or the molar alcohol absorptivity plot. Detecting the light may include detecting the light emitted at the one or more wavelengths determined by one or more of: the absorptivity or scattered reflectance light spectrum of water, the absorptivity or scattered reflectance light spectrum of alcohol, and/or the molar alcohol absorptivity plot. The method may include rapidly and sequentially emitting the light in the near-infrared or infrared light spectrum at the one or more wavelengths. The method may include continuously emitting the light in the near-infrared or infrared light spectrum at the one or more wavelengths. The representation of the PPG waveform for each of the one or more wavelengths may be an analog representation. The representation of the PPG waveform for each of the one or more waveforms may be a digital representation. Determining the measure of the amplitude of the representation of the PPG waveform may include one or more of: determining a difference between a maximum PPG value and minimum PPG value from a dynamic portion of the representation of PPG waveform, determining a route mean square (RMS) value from the dynamic portion of the PPG waveform, determining a maximum PPG peak value from the dynamic portion of the PPG waveform, determining a minimum PPG peak value from the dynamic portion of the PPG waveform, and/or determining a root sum of squares (RSS) from the dynamic portion of the PPG waveform. The emitted light may be transmitted through tissue of the human subject. The method may include detecting the transmitted light and outputting the representation of a photoplethysmography (PPG) waveform for each of the one or more wavelengths. The emitted light may be scattered in tissue of the human subject. The method may include detecting reflected scattered light at outputting the representation of a photoplethysmography (PPG) waveform for each of the one or more wavelengths.

The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.

Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:.

Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings.

System <NUM>, <FIG> and <FIG>, for noninvasively measuring blood alcohol concentration in blood using light includes one or more emitters, e.g., emitters <NUM>, <NUM>, <NUM> and <NUM>, each configured to emit light <NUM> in the near infrared light spectrum (e.g., about <NUM>,<NUM> to about <NUM>,<NUM>) or the infrared light spectrum (e.g., about <NUM>,<NUM> to about <NUM>,<NUM>) at one or more wavelengths that respond to varied chromophore concentrations of alcohol, e.g., ethanol, and water in the blood <NUM> of artery or vein <NUM> of a human subject. In the example shown in <FIG>, light <NUM> at the one or more wavelengths provided by one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> is shown transmitting through tissue <NUM>, e.g., the tissue of an area of the human subject, such as an arm, wrist, leg, foot, ankle, hand, finger, and the like, through blood <NUM> and exiting tissue <NUM> as shown. In the example shown in <FIG>, light <NUM> at the one or more wavelengths provided by one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> is shown scattering through tissue <NUM> and then reflecting from blood <NUM> as shown. Although as shown in <FIG> and <FIG>, system <NUM> includes four emitters <NUM>, <NUM>, <NUM>, and <NUM>, system <NUM> may include only one emitter or may include more than four emitters, as needed and known by those skilled in the art.

Each of emitters <NUM>, <NUM>, <NUM>, and <NUM> is preferably a small sized, compact emitter, e.g., having a size of about <NUM> in diameter, e.g., available from Eblana Photonics, Dublin, Ireland, Model No. EP1278-DM-TP39. One or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> are preferably configured to emit light <NUM> at one or more wavelengths using narrow wavelength light emitting diodes (LEDs), laser diodes, or similar small sized, compact narrowband light sources that can be integrated into a wearable device, e.g., the size of wearable fitness device, a smartwatch, and the like, as discussed below,.

One or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> preferably emit light <NUM> at the one or more wavelengths of light that respond to varied chromophore concentrations in blood <NUM> of the human subject, e.g., ethanol, water, oxygenated blood, glucose, and the like. In one design, the one or more wavelengths of light <NUM> emitted by emitters <NUM>, <NUM>, <NUM>, and <NUM> may be determined or selected by an absorptivity or scattered reflectance light spectrum of alcohol and/or an absorptivity or scattered reflectance light spectrum of water. For example, emitter <NUM> may be configured to emit light <NUM> at one or more wavelengths preferably having a wavelength of about <NUM>, indicated at <NUM>, <FIG>, associated with peak <NUM> of absorptivity or scattered reflectance light spectrum plot <NUM> of ethanol, emitter <NUM> may be configured to emit light <NUM> at one or more wavelengths having a wavelength of about <NUM>, indicated at <NUM>, associated with peak <NUM> of absorptivity or scattered reflectance light spectrum plot <NUM> of water, emitter <NUM> may be configured to emit light <NUM> at one or more wavelengths having a wavelength of about <NUM>, indicated at <NUM>, associated with peak <NUM> of light absorptivity or scattered reflectance plot <NUM> of ethanol, and emitter <NUM> may be configured to emit light <NUM> at one or more wavelengths having a wavelength of about <NUM>, indicated at <NUM>, associated with peak <NUM> of absorptivity or scattered reflectance light spectrum plot <NUM> of ethanol.

The one or more wavelengths of light <NUM> emitted by one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> may also be determined or selected by referencing one or more molar absorptivity plots. A molar absorptivity plot preferably spans the full light spectrum of near infrared or infrared light and provides the molar reflectance/absorptivity, a linear slope of concentration/molarity versus absorbance/reflectance for each of the one or more wavelengths, and may be used to select or determine the one or more wavelengths with the highest slope (response to change in concentration). For example, <FIG> shows an example of a molar absorptivity plot <NUM> for emitter <NUM>, <FIG> and <FIG>, which emits light <NUM> at one or more wavelengths having a wavelength of about <NUM> for peak <NUM>, <FIG>, where the absorption or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water is measured. <FIG> shows an example of molar absorptivity plot <NUM> for emitter <NUM> which emits light at one or more wavelengths having a wavelength of about <NUM> for peak <NUM> where the absorption or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water is measured. <FIG> shows an example of molar absorptivity plot <NUM> for emitter <NUM> which emits light at one or more wavelengths having a wavelength of about <NUM> for peak <NUM> where the absorption or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water is measured. <FIG> shows an example of molar absorptivity plot <NUM> for emitter <NUM> which emits light at one or more wavelengths having a wavelength of about <NUM> for peak <NUM> where the absorption or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water is measured.

As known by those skilled in art, the slopes shown in <FIG> are dependent on if water or alcohol absorbs more transmitted light when compared to each other. For example, if water absorbs more light than alcohol, as the alcohol concentration is increased, more light will be transmitted through to the detector and the response of the light by the detector will go up. This example would constitute a positive slope, e.g., as shown in <FIG> for emitters E-<NUM> and E-<NUM>. If alcohol absorbs more light than water, the opposite would be true and a negative slope would be the result, e.g., as shown in <FIG> for emitters E-<NUM> and E-<NUM>. In terms of scattering, if alcohol scatters more light than water, higher concentrations would scatter light back to the detector constituting a higher response for increased alcohol concentrations and a positive slope. The opposite is true (negative slope) if water scatters more light than alcohol.

System <NUM>, <FIG> and <FIG>, also includes one or more detectors, e.g., detector <NUM>, <FIG>, or detector <NUM>' <FIG>, which detect light <NUM> emitted at the one or more wavelengths emitted by one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> discussed above, e.g., transmitted light <NUM> as shown in <FIG> or reflected scattered light <NUM> as shown in <FIG>. Detector <NUM>, <NUM>' outputs a representation of a PPG waveform in response to detected one or more of the one or more wavelengths emitted by emitters <NUM>, <NUM>, <NUM>, and <NUM> discussed above. For example, <FIG> shows an example of the representation of PPG waveform <NUM> for the one or more wavelengths output by detector <NUM>, <NUM>', <FIG> and <FIG>, in response to light <NUM> detected by detector <NUM>, <NUM>' from emitter <NUM>. PPG waveform <NUM> preferably includes static portion <NUM> and dynamic portion <NUM>. As known by those skilled in the art, the static portion of a PPG waveform varies with all characteristics of each human subject, the activities of each human subject, and the environment where the human subject is located and dynamic portion varies with each blood volume change associated with the heartbeat of the human subject. In this example, detector <NUM>, <NUM>', <FIG> and <FIG>, also preferably outputs a PPG waveform <NUM>, <FIG>, in response to the light <NUM> detected from emitter <NUM> with static portion <NUM> and dynamic portion <NUM>. Detector <NUM>, <NUM>' also preferably outputs PPG waveform <NUM>, <FIG>, in response to the light <NUM> detected from emitter <NUM> with static portion <NUM> and dynamic portion <NUM> of PPG waveform <NUM>, <FIG>, in response to the light <NUM> detected from emitter <NUM>.

One advantage of using the dynamic portion of the PPG waveform by system <NUM> and the method thereof, discussed below, is that common factors that impact spectroscopy, such as tissue density, hydration, melanin concentration, ambient light, and the like, e.g., in static portions <NUM>, <NUM>, <NUM>, and <NUM>, <FIG>, of PPG waveforms <NUM>, <NUM>, <NUM>, and <NUM>, respectively, are calculated out by processing subsystem <NUM> which preferably uses the quiescent portion of the cardiac cycle to remove the absorbance due to static tissue and fluid, e.g., the dynamic portions <NUM>, <NUM>, <NUM>, and <NUM> of the PPG waveforms <NUM>, <NUM>, <NUM>, and <NUM>, respectively.

Detector <NUM>, <NUM>', <FIG> and <FIG>, is preferably a small sized, compact detector, having a size of less than about <NUM> by about <NUM>, e.g., available from Thorlabs, Newton, NJ, Model No. FDPS3X3, such that system <NUM> can be configured as a wearable device, as discussed below.

System <NUM> also includes processing subsystem <NUM>, <FIG> and <FIG>, coupled to one or more emitters <NUM>, <NUM>, <NUM>, and <NUM> and one or more detectors <NUM> as shown. Processing subsystem <NUM> determines a measure of an amplitude of the representation of the PPG waveform for each of the one or more wavelengths and determines the blood alcohol concentration (BAC) by referencing the measured amplitude for each of the one or more wavelengths to a molar absorptivity plot which indicates a measure of the absorptions or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water.

For example, in one design, processing subsystem <NUM> preferably determines a measure of the amplitude of the representation of the PPG waveform for each of the one or more wavelengths by one or more of: determining a difference between a maximum PPG value and a minimum PPG value from the dynamic portion of the PPG waveform, determining a route mean square (RMS) value from the dynamic portion of the PPG waveform, determining a maximum PPG peak value from the dynamic portion of the PPG waveform, determining a minimum PPG peak value from the dynamic portion of the PPG waveform, and/or determining a root sum of squares (RSS) from the dynamic portion of the PPG waveform.

In this example, processing subsystem <NUM> preferably determines a measure of one or more of amplitudes <NUM>, <NUM>, <NUM>, or <NUM>, <FIG>, of the representation of the PPG waveform associated with emitter <NUM> by determining a difference between a maximum PPG value and a minimum PPG value from any of amplitudes <NUM>, <NUM>, <NUM>, or <NUM> from dynamic portion <NUM> of the PPG waveform <NUM>, where the maximum PPG value is exemplarily indicated at <NUM> and minimum PPG value is indicated at <NUM>, Processing subsystem <NUM> may also determine a measure of one or more of amplitudes <NUM>, <NUM>, <NUM>, or <NUM> of the representation of the PPG waveform <NUM> associated with emitter <NUM> by determining a RMS value from dynamic portion <NUM> of the PPG waveform <NUM> or determining a RSS value from dynamic portion <NUM> of the PPG waveform <NUM>, Processing subsystem <NUM> may also determine the measure of one or more of amplitudes <NUM>, <NUM>, <NUM>, or <NUM> of the representation of the PPG waveform <NUM> associated with emitter <NUM> by determining a maximum PPG value of dynamic portion <NUM> of PPF waveform <NUM>, exemplarily indicated at <NUM> or determining a minimum PPG value of dynamic portion <NUM> of PPF waveform <NUM>, exemplarily indicated at <NUM>.

In a similar manner, processing subsystem <NUM> preferably determines a measure of one or more of amplitudes <NUM>, <NUM>, or <NUM>, <FIG>, of PPG waveform <NUM>, associated with emitter <NUM>, amplitudes <NUM>, <NUM>, or <NUM>, <FIG>, of the representation of PPG waveform <NUM> associated with emitter <NUM>, or amplitudes <NUM>, <NUM> or <NUM>, <FIG>, of the representation of PPG waveform <NUM> associated with emitter <NUM>.

Processing subsystem <NUM> determines the BAC by referencing the measured amplitude for each of the one or more wavelengths discussed above to a molar absorptivity plot which indicates a measure of the absorptions or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water.

For example, the determined value of the measure of one or more of amplitudes <NUM>, <NUM>, <NUM>, or <NUM>, <FIG>, of the representation of the PPG waveform <NUM> associated with emitter <NUM> provided by processing subsystem <NUM> is referenced to a molar absorptivity plot which indicates a measure of the absorptions or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water, e.g., the determined value indicated at point <NUM>, <FIG>, of the measure of one or more of amplitudes <NUM>, <NUM>, <NUM>, or <NUM> is referenced to molar alcohol absorptivity plot <NUM> for emitter <NUM>, and the level of alcohol, e.g., ethanol, in the blood <NUM>, <FIG> and <FIG>, is determined, indicated at <NUM>, which correlates to BAC.

The same process is preferably performed by processing subsystem <NUM> using the determined the value of the measure of one or more of amplitudes <NUM>, <NUM>, or <NUM>, <FIG> of PPG waveform <NUM>, e.g., the determined value indicated a point <NUM>, <FIG>, referenced to molar absorptivity plot <NUM> for emitter <NUM> to determine BAC, indicated at <NUM>, the determined the value of the measure of one or more of amplitudes <NUM>, <NUM>, or <NUM>, <FIG>, of PPG waveform <NUM>, e.g., the determined value indicated a point <NUM>, referenced to molar absorptivity plot <NUM> for emitter <NUM> to determine BAC, indicated at <NUM>, and/or determine the determined value of the measure of one or more of amplitudes <NUM>, <NUM> or <NUM>, <FIG>, of PPG waveform <NUM>, e.g., the determined value indicated a point <NUM>, <FIG>, which is referenced to molar absorptivity plot <NUM> for emitter <NUM> to determine BAC, indicated at <NUM>.

Processing subsystem <NUM>, <FIG> and <FIG>, is preferably configured to average the determined BAC at each of the one or more wavelengths to enhance the accuracy of the measured blood alcohol concentration.

In one design, processing subsystem <NUM> may rapidly and sequentially turn on and off one of more of emitters <NUM>, <NUM>, <NUM>, and <NUM> emitting light <NUM> at the one or more wavelengths. In another design, processing subsystem <NUM> may continuously turn on one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> such that light <NUM> is continuously emitted.

Processing subsystem <NUM> may be a processor, one or more processors, an application-specific integrated circuit (ASIC), firmware, hardware, digital circuitry, analog circuitry, a combination of digital circuitry and analog circuitry, and/or software (including firmware, resident software, micro-code, and the like) or a combination of both hardware and software. Processing subsystem <NUM> also preferably includes one or more programs stored in a memory which are preferably configured to be executed by the one or more processors. Computer program code for the programs for carrying out the instructions or operation of processing subsystem <NUM> may be written in any combination of one or more programming languages, including an object-oriented programming language, e.g., C++, Smalltalk, Java, and the like, or conventional procedural programming languages, such as the "C' programming language, Assembly language or similar programming languages.

Processing subsystem <NUM> and/or detector <NUM>, <NUM>' may provide the representation of the PPG waveform for each of the one or more wavelengths discussed above with reference to one or <FIG> as an analog representation or a digital representation, as known by those skilled in the art.

In one design, system <NUM>, <FIG> and <FIG>, also preferably includes emitter <NUM> coupled to processing subsystem <NUM> which is preferably emits light at the one or more wavelengths having a wavelength where absorptivity or scattered reflectance light spectrum <NUM> of water, <FIG>, and absorptivity or scattered reflectance light spectrum <NUM> of alcohol intersect, e.g., at point <NUM> at about <NUM>, indicated <NUM>, or any of the points where absorptivity or scattered reflectance light spectrum <NUM> of water and scattered reflectance absorptivity or scattered reflectance light spectrum <NUM> of alcohol intersect. When emitter <NUM>, <FIG>, emits light at this wavelength, the ratio of the alcohol concentration and the water concentration are the same and molar absorptivity plot <NUM>, <FIG>, will be zero, e.g., a flat line as shown. Processing subsystem <NUM> is preferably configured to reference one or more of the one or more wavelengths emitted by one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM> discussed above to a wavelength with a molar absorptivity plot of zero to further increase the accuracy of the BAC detected. This allows system <NUM> and the method thereof to continuously calibrate itself by allowing this reference to increase and decrease with certain hemodynamic changes, but its increase and decrease will not be due to alcohol. Thus, as a reference, it can eliminate other factors that may be impacting the estimating of BAC,.

System <NUM>, <FIG> and <FIG>, preferably include memory <NUM> coupled to processing subsystem and power supply <NUM> coupled to processing subsystem <NUM>, one or more of emitters <NUM>, <NUM>, <NUM>, and <NUM>, and detector <NUM>, <NUM>' as shown. Memory <NUM> and power supply <NUM> preferably each have a small compact size. As discussed above, one or more of emitters <NUM>, <NUM>, <NUM>, <NUM>, detector <NUM>, <NUM>' and processing subsystem <NUM> also have a small, compact size. In one design, one or more of emitters <NUM>, <NUM>, <NUM>, <NUM>, detector <NUM>, <NUM>', processing subsystem <NUM>, memory <NUM>, and power supply <NUM> are enclosed in small compact housing <NUM> such that system <NUM> may be configured as a wearable device, e.g., the size of a Fitbit®, smartwatch, or similar type device, e.g., as shown in <FIG>,.

As discussed above with reference to one or more of <FIG>, system <NUM> may rely on the transmission of light <NUM>, <FIG>, at the one or more wavelengths provided by one or more of one or emitters <NUM>, <NUM>, <NUM>, and <NUM> through tissue <NUM> and blood <NUM> of a human subject. In this example, one or more detectors <NUM> are preferably located on an opposite side of tissue <NUM> as one or more emitters <NUM>, <NUM>, <NUM>, and <NUM> as shown and detect light <NUM> at one or more wavelengths transmitted though tissue <NUM> including blood <NUM> in artery or vein <NUM>. System <NUM> may also rely on the scattering of light <NUM>, <FIG>, at the one or more wavelengths provided one or more of emitters <NUM>, <NUM>, <NUM>, <NUM>. Scattering of light <NUM> is related to transmission of light <NUM> discussed above but instead of detecting light <NUM> which is transmitted through tissue <NUM>, as shown in <FIG>, one or more detectors <NUM>', <FIG>, detect scattered reflected light <NUM> at one or more wavelengths emitted by one or more one or more emitters <NUM>, <NUM>, <NUM>, and <NUM> from tissue <NUM> including blood <NUM> in artery or vein <NUM> as shown. In this design, one or more detectors <NUM>' are located on the same side of tissue <NUM> as one or more of emitters <NUM>, <NUM>, <NUM>, <NUM> as shown. In this example, the penetration depth of light <NUM> into tissue <NUM> may depend on the power applied to one or more emitters <NUM>, <NUM>, <NUM>, and <NUM> and the separation distance between emitters <NUM>, <NUM>, <NUM>, and <NUM> and one or more detectors <NUM>'. As known by those skilled in the art, scattering light absorptivity spectrums of alcohol and water may be different from transmission light absorptivity spectrums of alcohol and water as shown in the example shown in <FIG>, however the same concept still applies to analyzing and determining the concentration of alcohol by system <NUM> as discussed above.

One example of the method for noninvasively measuring blood alcohol concentration using light includes emitting light in the near infrared or infrared spectrum at one or more wavelengths that respond to varied chromophore concentrations of ethanol in water in blood of a human subject, step <NUM>, <FIG>. The method also includes detecting light emitted at the one or more wavelengths, step <NUM>, and outputting a representation of the PPG waveform at each of the one or more wavelengths, step <NUM>. The method also includes determining a measure of an amplitude of the representation of the PPG waveform for each of the one or more wavelengths, step <NUM>, and determining 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 absorptions or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water, step <NUM>.

The result is system <NUM> and the method thereof provides a small compact device that can be discretely worn by a user to noninvasively measure blood alcohol concentration in blood using light. System <NUM> and the method thereof may have a significant impact in both the commercial and medical fields by offering the advantages over conventional system and methods including, inter alia, high accuracy BAC measurements within minutes of alcohol consumption, high temporal resolution to correlate BAC to a physiological and/or psychological response during clinical studies, very small compact size to allow for integration into commercially accepted wearable devices, improved user compliance through discreet measurements, and long hardware lifespan with no moving or consumable components. System <NUM> and the method thereof also provides users with the ability to passively and accurately monitor their alcohol consumption for personal reasons and also aids the research community to better understand how alcohol consumption correlates to overall health. System <NUM> and method for noninvasively measuring blood alcohol concentration in blood using light may greatly improve clinician access to high temporally resolute data to broaden their understanding of the short term and long term impacts of alcohol consumption. The information provided by system <NUM> configured as wearable device may provide users with the ability to monitor their own alcohol consumption with a deeper understanding of the consequences of alcohol consumption.

Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words "including", "comprising", "having", and "with" as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments,.

Claim 1:
A system for noninvasively measuring blood alcohol concentration using light, the system comprising:
one or more emitters (<NUM>, <NUM>, <NUM>, <NUM>) each configured to emit light (<NUM>) 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 (<NUM>,<NUM>') configured to detect light (<NUM>) emitted at the one or more wavelengths and a processing subsystem (<NUM>) coupled to the one or more emitters (<NUM>, <NUM>, <NUM>, <NUM>) and the one or more detectors (<NUM>, <NUM>');
characterised in that the one or more detectors are configured to output a representation of a photoplethysmography (PPG) waveform (<NUM>) said representation including a static portion (<NUM>) and a dynamic portion (<NUM>) for one or more of the one or more wavelengths; and wherein;
the processing subsystem (<NUM>) is configured to determine a measure of an amplitude (<NUM>) of the dynamic portion of the representation of the PPG waveform (<NUM>) for each of the one or more wavelengths and determine the blood alcohol concentration by referencing the measured amplitude (<NUM>) for each of the one or more wavelengths to a molar absorptivity plot (<NUM>) which indicates a measure of the absorption or scattering at alcohol and water solutions ranging between a solution of <NUM>% alcohol and a solution of <NUM>% water.