Noninvasive in-vehicle alcohol detection with wavelength-modulated differential photothermal radiometry
Spotlight summary: The development of techniques that can non-invasively and reliably detect whether an individual is alcohol-impaired before attempting to drive has tremendous implications for improving road safety and decreasing the number of alcohol-related traffic fatalities. Alcohol ignition interlocks are becoming increasingly common in vehicles of Driving While Intoxicated (DWI) offenders to assess an individual’s blood alcohol concentration and determine whether it is safe to start the vehicle. However, it would be valuable to develop techniques that could be accessible for use in the general population to assess any individual’s degree of alcohol impairment before starting one’s vehicle. A handful of techniques have been considered for measuring an individual’s blood alcohol concentration, including tissue spectrometry, distant spectrometry, electrochemical/chemical-reaction based devices (such as breathalyzers) and objective behavioral tests of vision and driving performance. Two prototype devices, TruTouch and Autoliv, are currently being developed by the Driver Alcohol Detection System for Safety in an effort to better detect alcohol concentration and prevent alcohol-impaired individuals from driving. While promising, these technologies may possess some limitations preventing their ubiquitous use, including weak and confounding absorption properties for detecting ethanol and a potentially large degree of variability in measuring breath alcohol concentration. One technique that could potentially overcome the issues of weak absorption and measurement variability is wavelength modulated differential photothermal radiometry (WM-DPTR).
In this paper, Guo et al. test the ability of their WM-DPTR to detect ethanol over a range of blood alcohol concentrations (inclusive of the legal limits for driving in Europe, the United States and Canada) in an ethanol and water solution phantom, as well as an ethanol and blood serum solution that was diffused into human skin. The WM-DPTR technique uses two out-of-phase modulated quantum cascade lasers operating at wavelengths corresponding to the peak of the ethanol absorption band and its adjacent minimum to noninvasively measure ethanol in the blood. By selectively tuning the amplitude ratio and optical phase shift of the signals generated by the two lasers, the authors are able to optimize their alcohol detection abilities to achieve high sensitivity and resolution. The authors found that the WM-DPTR technique was superior to standard single-PTR techniques that were not able to resolve ethanol concentrations over the range of blood alcohol concentrations that were tested and detected using WM-DPTR. Moreover, by capitalizing on the technique’s photothermal properties and tuning capabilities, the authors are able to use WM-DPTR to differentiate ethanol concentration from glucose concentration (which share the same fundamental absorption peak) and account for variations in blood glucose that might otherwise confound the accuracy of measuring ethanol concentration in diabetic individuals.
In conclusion, Guo et al. provide preliminary evidence that WM-DPTR can be used to noninvasively and reliably measure ethanol over relevant ranges of blood alcohol concentrations. While the technique has shown exciting results in phantoms, it still needs to be tested in vivo to better assess its repeatability and reproducibility. Nevertheless, it will be exciting to follow the testing of WM-DPTR in living systems to better understand whether the technique can be translated and developed into an alcohol ignition interlock with universal application to the general public in hopes of improving public safety.
ToC Category: Biosensors and Molecular Diagnostics
|OCIS Codes:||(170.1470) Medical optics and biotechnology : Blood or tissue constituent monitoring|
|(300.6430) Spectroscopy : Spectroscopy, photothermal|
|(280.1415) Remote sensing and sensors : Biological sensing and sensors|
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