Ethanol Intoxication Sensing Technologies and Techniques: Comparison
Please note this is a comparison between Version 1 by Szymon Paprocki and Version 2 by Peter Tang.

Ranging from casual drinking or as a part of celebration to more extreme binge drinking or alcohol dependence/alcoholism, often referred to as alcohol use disorder (AUD), alcohol consumption has also been associated with the development of several types of cancer. The field of alcohol intoxication sensing is over 100 years old, spanning the fields of medicine, chemistry, and computer science, aiming to produce the most effective and accurate methods of quantifying intoxication levels. 

  • ethanol
  • intoxication
  • sensors
  • devices

1. Introduction

Ethanol consumption is a major component of social life in the Western world. Ranging from casual drinking or as a part of celebration to more extreme binge drinking or alcohol dependence/alcoholism, often referred to as alcohol use disorder (AUD) [1], alcohol consumption has also been associated with the development of several types of cancer [2]. With high frequency of consumption of alcoholic beverages and the corresponding effects of alcohol intoxication on the body and behavior of individuals, a necessity for quantification of intoxication has become an important part in assessing the state of an individual. Driving under the influence (DUI) of alcohol in the UK is related to an estimated 13% of all fatal road accidents and is a major cause of death for males between 15 and 59 years of age [3]. In an effort to prevent these tragedies, several methods have been developed to estimate intoxication levels spanning many fields, such as biochemistry, physiology, photonics, electronics, image analysis, and artificial intelligence.
Alcohol intoxication is a standardized metric denoted by blood alcohol concentration (BAC) only and not the effect it has on an individual, thus not accounting for tolerance resulting from regular exposure to ethanol. Although similar symptoms of intoxication can be seen amongst individuals, the influence of alcohol tolerance remains a poorly explored phenomenon in the context of the wider population. The BAC level corresponds to the weight of ethanol in milligrams per 100 mL of blood. The level of intoxication is positively correlated with the amount of ethanol in the bloodstream, with the high end of ethanol intoxication at 0.5% (500 mg/dL) and with levels as low as 0.35% (350 mg/dL) being linked to death or serious harm to the individual or those around them [4]. Regular consumption of excessive amounts of alcohol is also associated with the development of liver disease and increased blood pressure, making those individuals more susceptible to health complications in the future [5]. The legal drinking limit for driving in the UK is 80 mg per 100 mL of blood, equivalent to a BAC of 0.08, which can be categorized as one of the higher levels of alcohol permissible to drive, whilst many European countries and Middle Eastern countries allow for a very low level of intoxication (BAC 0.02) or prohibit driving under the influence of alcohol altogether under a “zero tolerance” policy. The territory with the highest permissible level of BAC is the Cayman Islands allowing a BAC level of 0.10. Besides DUI, alcohol consumption can also be linked to crimes, such as theft and criminal damage, and in such circumstances alcohol serves as a catalyst for antisocial behavior and violent crime [6]. Alcohol consumption puts a significant burden on public services. Combining the costs of dealing with alcohol-related crime, loss of productivity through unemployment and sickness, and the cost and burden on the National Health Service (NHS), the cost of alcohol on society is estimated to be GBP21 billion per year [7], although the real figure is thought to be even higher. Reviews on the subject of economic impacts of alcohol consumption express the cost figure as percentage of gross domestic product (GDP) ranging between 0.45% and 5.44% annually [8].
Short-term influences of alcohol intoxication, however, do not carry such damaging consequences, yet they are not without harm. Acute intoxication can have damaging effects on people diagnosed with cancer or currently taking antibiotics. The reaction of ethanol in the liver can trigger inflammation and damage the liver of the user. Other cases where acute consumption poses a risk of damage is particularly seen amongst people who are suicidal, increasing the risk of taking their life. [9]. Ethanol affects the body by influencing the central nervous system through the inhibition of gamma-aminobutyric acid (GABA) receptors [10]. This results in reduced cognitive ability, slurred speech, loss of balance, and reduced social inhibition. Long-term consumption can lead to alcohol use disorder (AUD). Neuroscience researchers have also found a correlation between neuron activity and metabolites of ethanol, such as acetic acid [11]. This correlation may suggest that other chemical imbalances contribute to intoxication effects. The effects of acetic acid on the nervous system have not been studied in as much depth as ethanol, and could potentially prove to be an important component for quantifying intoxication influences or relating to the addictive properties of alcohol consumption. Globally, excessive consumption of alcohol leads to AUDs and addictions, with an estimated 586,780 sufferers of AUD just in the UK and only 18% receiving treatment [12].
With so many problems associated with alcohol consumption, methods of estimating alcohol intoxication were reported in medical literature as early as 1920 by Widmark [13]. With further development in technology and chemical analytics, several methods, such as gas chromatography, became available for measuring intoxication levels in a variety of bodily fluids. Similarly, this development in technology and analytical techniques gave rise to the most notable alcohol intoxication measuring device, the Breathalyzer™, a breath alcohol content (BrAC) measuring device. This method allows for remote BAC testing, particularly for traffic safety, without the need to send blood samples for laboratory analysis [14].

2. Toxicology of Intoxication

Intoxication can be defined as loss of control over actions or behavior changes under the influence of a drug. Intoxication due to ethanol can be divided into three main parts: initial take-up, the peak, and the decay stage. This can be illustrated by studies performed on human volunteers to investigate the changes of alcohol in their blood over time [15]. The initial uptake of ethanol causes the blood alcohol concentration (BAC) to raise rapidly, reaching peak intoxication between 30 to 60 min, although that number is heavily dependent on the dosage. After that, the peak BAC levels begin to decay, reaching zero between six to eight hours after initial consumption. This, however, is also dependent upon the volume of ethanol consumed. The standard unit of measurement of alcohol intoxication is not internationally agreed upon, with variation in the order of magnitude of measurement as well as the numerical systems used. In the medical literature, the consensus on measurement is to use BAC as volume of pure ethanol per 100 mL of blood, varying from 0 to 0.5, representative of concentration levels between 0 and 500 mg/dL. Considering the uptake of ethanol, this period is characteristic of euphoric behavior, including laughter, social inhibition, and generally increased well-being due to the release of hormones, such as serotonin. At the peak of intoxication, these effects begin to slowly fade away, due to decreasing levels of ethanol in the body. The roll-off stage is associated with increased tiredness and depression [16]. The primary influence of ethanol intoxication originates in the central nervous system through the inhibition of GABA receptors. Alcohol molecules inhibit the active site of GABA receptors, resulting in reduced cognitive function and decreased spatial awareness. Alcohol also contributes to the production of serotonin, resulting in a relaxed state of the consumer [17], hence enacting on the reward system of the brain. With time, these effects wear off, depending on several factors, such as age, sex, and body weight. The literature correlates sex with an aspect of varied breakdown of ethanol, possibly explained by the lower resting metabolic rate in women [18]. Tolerance is also a factor when considering the decay of ethanol in the blood, as has been demonstrated by people with AUD that can metabolize ethanol at a faster rate than occasional drinkers [19]. In the body, alcohol is subject to many chemical reactions, specifically those involved in its breakdown. A group of enzymes responsible for ethanol breakdown are known as alcohol dehydrogenases. These enzymes are responsible for breaking down alcohol into acetaldehydes and subsequently acetic acid. These waste products are dealt with in the body by means of various other enzymes. Specifically, acetic acid is a subject in the acid cycle for neutralization. It is key to highlight that high concentration of these acids can lead to acidosis, a symptom of alcohol poisoning, requiring medical attention in severe cases [20]. Besides inhibiting GABA receptors and being broken down by enzymes, alcohol also influences the function of the cardiovascular and pulmonary systems. Primarily, the impact of ethanol on the blood vessels extends to the function of relaxation by vasodilation. It is key to note that although alcohol relaxes the blood vessels, this is only seen for small doses of alcohol. This is also a contributing factor to the beneficial health impacts of alcohol. However, act as exclusively limited to small doses of alcohol. At higher levels of BAC, it begins to take on a pressor, restricting the blood vessels [21]. This once again can be attributed to the acids produced through the metabolic breakdown of ethanol, although the true origin of this effect is not clear. Alcohol affects a number of systems in the body, resulting in an intoxicated state. As mentioned previously, these effects manifest themselves in bodily organs, such as the heart, lungs, liver, and brain. However, these effects are short-lived and fade away after time. On the other hand, long-term consumption of excessive amounts of alcohol can contribute to a multitude of diseases, both physical and mental. Amongst them are the mental illness associated with dependence or addiction to alcohol. The root causes of these diseases are mostly unexplored in terms of explaining the susceptibility to developing an alcohol addiction [22]. Some research suggests that both genetic and environmental factors play a role in the development of AUD [23]. AUD is often characterized by large and frequent consumption of alcohol, as well as by withdrawal symptoms, some of which include tachycardia, tremors, sweating, delirium, seizures, insomnia, and anxiety [24]. Several treatments exist to help recovering people with AUD [25][26][25,26]. Regular and uncontrolled consumption of alcohol can lead to an AUD, which, if untreated, can become a gateway for development of more serious health problems, some of which are fatal. Cardiac health is significantly impacted by excessive and regular consumption of alcohol. Amongst the long-term effects of alcohol consumption are alcoholic cardiomyopathy (change of shape of the heart), high blood pressure, myocardial infarction (heart attack), arrythmias (irregular heart rhythm), fatal cardiac arrest, and stroke [27]. The association between heavy alcohol use and cardiovascular disease (CVD) is unclear. Discussion on this topic focuses on alcohol’s effect on the atherosclerotic process (hardening of blood vessels) in vessels and the toxic damage to the myocardium [28]. As the main site of alcohol metabolism, the liver experiences the most damage, although much of that is mitigated by its regenerative properties [29]. However, even that is not enough to prevent the tissue damage caused by excessive and prolonged consumption of alcohol. Chronic and excessive alcohol consumption results in the formation of hepatic lesions on the liver, including steatosis (deposition of fat in hepatocytes), hepatitis (inflammatory type of liver injury), and fibrosis (tissue scarring) [30]. Continuous damage to the tissue of the liver and the formation of scar tissue contributes to and increase the risk of developing liver cancer, a very prominent disease amongst heavy alcohol users. AUD and heart and liver damage are just a few of the many pathologies that can be attributed to excessive consumption of alcohol [31][32][31,32]. Alcohol-related disease is a big burden on the health system.

3. Technologies and Devices

The literature research view of ethanol intoxication sensors yielded several results encompassing different aspects of alcohol intoxication, i.e., behavioral, physiological, and chemical changes in the individual’s body. All the methods were categorized into six main sections: pharmacokinetic estimates, breath-sample testing, bodily fluids, physiological changes, transdermal, and optical spectroscopy. The findings and all the devices and techniques considered are summarized in Table 1.
Table 1.
Summary of ethanol detection devices and techniques.
As seen from Table 1, the field of alcohol intoxication sensing is filled with innovative methods of analyzing factors of intoxication, not exclusively changes in the concentration of ethanol biomarkers but also tracking physiological changes occurring during an intoxication episode. A great deal of attention in the literature is given to laboratory methodologies of detecting ethanol and its biomarkers through forensic analysis. These methods focus on establishing not only the intoxication level itself but also the exposure level, such as that seen in hair or nail samples, as opposed to gas chromatography blood testing. Several publications showcase the latest developments and ideas, for which the trial and experimental data are publicly available. Table 2 and Table 3 summarize these findings.
Table 2.
Performance of the most notable experimental devices and techniques.
Table 3.
Commercially available devices for ethanol intoxication sensing.

Product

Year

Type

Form Factor

Stage in Development

Performance Summary

Reference

Cost

Applications

1

Widmark E.M.P.

Nicloux Flask

Widmark flask

Chemical reaction

Intoxilyzer

(near-infrared spectroscopy)

1918

Bodily fluid testing

Well established

First direct measure of ethanol blood concentrations

Flask/blood extraction

High ($3.5k)

Early BrAC methods

Forensic testing

2

Widmark E.M.P. et al.

Widmark Flask

EBAC equation

Chemical reaction

1924

Bodily fluid testing

Flask/blood extraction

Largely inaccurate by modern standards, error in the ranges of ±20% from true value

Ljungblad et al. (Autoliv)

Prototypes in testing

Widmark Flask and early BrAC methods

Roadside safety

3

EBAC Equation

Estimation based on physiological factors

Brokenstein R.F. et al.

Breathalyzer

Urine alcohol test (strip)

Available to the general public

(photovoltaic assay)

Early estimation method

1961

Low ($10–25)

Revolutionary device in the field of portable testing devices for intoxication, susceptible to environmental error and variance in lung volume across the population

Equation

Workstation monitoring

Analysis of blood and bodily fluids

4

Photovoltaic Assay

Color change based on oxidation level

Breath alcohol

Portable device

Mishra et al.

Gas chromatography

THC and ethanol saliva sensing ring

Gold standard

2020

High ($50k)

Detection range: 0.1 to 1 mM (0.1 mM increments

RSD of 1.5% (n = 5)

Forensic analysis

Stable multianalyte sensing (THC)

5

Intoxilyzer

Saliva alcohol sensing (strip)

Available to the general public

Near-infrared spectroscopy

Low ($10–25)

Breath alcohol

Benchtop device

Workstation monitoring

6

Headspace chromatography

Fuel-Cell Analyzer

Current generated by ethanol oxidation

Breath alcohol

Gold standardPortable device

High ($70k)

Forensic analysis

7

Semiconductor Breath Analyzer

Strip color change

Breath alcohol

Portable device

Breast-milk testing kits

Available to the general public

Low ($10–25)

Home and child well-being

8

Ignition Interlock Breath Analyzer

Alcohol oxidation reaction—fuel cell

Breath alcohol

Portable device

9

Gas Chromatography

Evaporation and separation of components

Bodily fluid testing

Benchtop device

10

Headspace Gas Chromatography

Evaporation and separation of components

Bodily fluid testing

Benchtop device

11

Enzymatic Blood Testing

Strip color change

Modern estimation method

Strip test

12

EtG Test

Strip color change

Modern estimation method

Strip test

13

PPG Datum Line

Changes in PPG signal—systolic and diastolic

Physiological factor analysis

PPG analysis/modern estimation method

14

Face Heat-Map Distribution

IR image analysis of the forehead and nose

Physiological factor analysis

IR in-vehicle cameras

Commercial BrAC device

21

Quantic Tally

Alcohol in sweat

Transdermal sensor

Wristband

Chen et al.

PPG datum line analysis

2018

85% identification rate

18 ms processing and identification time

Commercial BrAC device

Wang et al.

ECG and PPG analysis

2017

95% identification rate

Only identifies if a subject is above 0.15 mg/dL

Commercial BrAC device

Rachakonda et al.

Multisensory steering wheel

2020

Detection between sober and intoxicated at 0.08 mg/dL

Accuracy of 93%

No reference stated

Kubieck et al.

IR facial imaging

2019

No specific correlation number states

Results indicate a very strong correlation between alcohol consumption and facial temperature distribution in all cases

Volvo SPA2

In testing

No reference stated

Roadside safety

SCRAM CAM

Bioimpedance spectroscopy

Generally available

2019

Noticeable changes between intoxication and reference group

Medium ($450 monthly)

Weak correlation with absolute impedance

(r = 0.47)

Sensitivity 92%

Specificity 76%

Commercial BrAC device

Blood-sample analysis (method unknown)

High-risk individual monitoring

Wen-fei et al.

NIR dynamic spectrum

2011

TT1100

Calibration set:

Discontinued

R = 0.9672

Prediction set:

R = 0.9384

Relative error between 0.6 and 9%, average error 3.26%

Workstation monitoring

Hospital biochemical analysis

Yamakoshi et al.

Integrated sphere finger-PPG

2015

TTT2500

Commercially available

High ($300 per week)

Lower SNR compared to traditional PPG acquisition method

Sensitivity of 0.43 ± 0.29

Workstation monitoringNo reference

(Pilot Study)

Kim et al.

Iontophoretic biosensing system

2016

Correlation recorded = 0.912

High specificity for ethanol

Increased accuracy of the system at higher ethanol concentrations

FDA-approved commercial BrAC device

TT Mark III

In testing

Roadside safety

X. Guo et al.

Rockley

PhotonicsVitalSpex

Wavelength-modulated differential photometry

2018

High ethanol resolution: 5–6 mg/dL

Lag of 10–15 between ISF and blood ethanol

Correlation between 0.96 and 0.98

Commercially available BrAC device

First prototype release expected in 2023

Personal monitoring

Lansborp et al.

Wearable enzymatic alcohol biosensor

2019

Linear sensor response between 0 and 0.05 mol/L

Results of the sensor closely resemble those predicted by Widmark equation, however fall short during the decay stage, and generally underestimate ethanol readings

Widmark equation

(BrAC device deemed impractical for application)

15

Volvo SPA2 Platform

Head position

Physiological factor analysis

Arakawa et al.

In-vehicle cameras

Skin ethanol gas

2020

Strong correlation of 0.995

Range of estimation 73.9–112.1 ppb/cm2

Results demonstrate superiority over an ordinary biosniffer

No reference for intoxication measure stated

16

Bioimpedance Spectroscopy

Impedance across the body, legs, and arms

Transdermal sensor

Experimental device/benchtop

     

Results indicate strong correlation for at least 3 distinct levels of ethanol

 

17

SCRAM CAM

Alcohol in sweat

Transdermal sensor

Selvam et al.

Wristband

EtG biochemical sensor

2016

Ethanol detection in the range of 0.001–100 ug/L

Lower sensitivity at 1 ug/L with gold electrodes compared to ZnO (sensitivity of 0.001ug/L)

Three distinct levels of EtG identified

Correlation of 0.97

 

18

GinerWrist TAS

Alcohol in sweat

Transdermal sensor

Wristband

Venugopal et al.

ISF sensor for remote continuous alcohol monitoring

19

BACtrack Skyn

Alcohol in sweat

Transdermal sensor

Wristband

2008

Generally strong correlation between 0.7203 to 0.866

Correlation between BrAc = 0.879

BrAC device and blood testing

Tehrani et al.

Microneedle ISF Lactate/Ethanol and Glucose Sensor

2022

Low cross-talk between sensing elements

Correlation of 0.94

Commercially available BrAC device

20

Proof

Alcohol in sweat

Transdermal sensor

Wristband

22

Iontophoretic Biosensing System

Stimulated emittance of ethanol from the skin

Transdermal sensor

Tattoo sticker

23

Enzymatic Biosensors

Enzymatic redox reaction

Transdermal sensors

Transdermal sensors

24

Biosniffer

Inert gas and fluorescence

Transdermal sensors

Benchtop device

25

EtG Sensor

By-product of ethanol metabolism

Transdermal sensor

Wristband

26

ISF Sensor

Extraction of ISF

Transdermal sensor

Wristband

27

ISF Microneedle Sensor

Sensing of ethanol in the ISF

Transdermal sensors

Skin-attachable patch

28

TTT1100

Spectroscopic measurement of tissue

Optical tissue spectroscopy

Benchtop

29

TTT2500

Spectroscopic measurement of tissue

Optical tissue

spectroscopy

Benchtop

30

NIR Dynamic Spectrum

Spectroscopic measurement of tissue/physiological parameter

Optical tissue

spectroscopy

Algorithm

31

Autoliv

Spectroscopic measurement of exhaled air

Strip color change

Bodily fluid testing

Chaplik et al.

Optical breath spectroscopy

In-vehicle module

32

WD-DPTR

Spectroscopic measurement of tissue

Optical tissue spectroscopy

Benchtop device

33

Pulse Alcometry

Absorption of light at specific wavelengths and pulse variation

Optical tissue spectroscopy

PPG adaptation

34

THC and Alcohol Saliva Sensor

Saliva content reaction with electrodes

Bodily fluid testing

Ring

35

Breast-Milk Sensing

Strip test

36

Rockley Photonics VitaSpex Pro

Spectroscopic measurement of tissue

Optical tissue spectroscopy

Wristband

37

Hair Analysis

Detection of EtG and EtPA

Modern estimation method

Laboratory test

38

Nail Analysis

Detection of EtG and EtPA

Modern estimation method

Laboratory test