The objective of the present investigation performed within the Driver Alcohol Detection System for Safety (DADSS) program is to demonstrate the effect of further recent improvements of the breath-based nondispersive infrared sensor technology in realistic settings. More specifically, sensor systems installed in vehicles have been tested by: a) exposing them to a controlled, realistic breathing pattern from artificially generated gas pulses mimicking that of an intoxicated driver and b) human subjects entering a test vehicle and performing a simulated drive while under the influence of alcohol. The tests with artificial gas pulses correspond to human directed forced exhalation from positions up 70 cm from the sensor. The tests provide experimental evidence that in-vehicle, driver breath alcohol determination is feasible with a single sensor positioned at the top of the steering column. The human subject study was designed to test both active and passive detection modes. Good correlation to the breath alcohol reference instrument was found in both cases over the full range of alcohol intoxication exceeding 0.08 percent (the legal limit in most U.S. states). Time to detection is a remaining challenge of the passive mode but is manageable by requesting an active breath in the absence of reliable data. The results illustrate the feasibility of using breath-based NDIR based sensors in different operational modes. In the active mode, a simple exhalation directed towards the sensor is enough for a test to be approved and the alcohol content quantified. In the passive mode, the operator does not actively interact with the sensor. In a real-world scenario, sensors set to a passive mode could be used for driver monitoring and to assist the driver to choose a smarter option when alcohol is detected. The overall conclusion from the present investigation is that in-vehicle breath-based alcohol determination is feasible with the current state of the art sensor technology.

Alcohol breath testing on a larger scale will save lives. Alcohol intake affects the human body by significantly longer response time to external stimuli. In demanding situations where the senses n ...

OBJECTIVE:The research objective of the present investigation is to demonstrate the present status of passive in-vehicle driver breath alcohol detection and highlight the necessary conditions for large-scale implementation of such a system. Completely passive detection has remained a challenge mainly because of the requirements on signal resolution combined with the constraints of vehicle integration. The work is part of the Driver Alcohol Detection System for Safety (DADSS) program aiming at massive deployment of alcohol sensing systems that could potentially save thousands of American lives annually.METHOD:The work reported here builds on earlier investigations, in which it has been shown that detection of alcohol vapor in the proximity of a human subject may be traced to that subject by means of simultaneous recording of carbon dioxide (CO2) at the same location. Sensors based on infrared spectroscopy were developed to detect and quantify low concentrations of alcohol and CO2. In the present investigation, alcohol and CO2 were recorded at various locations in a vehicle cabin while human subjects were performing normal in-step procedures and driving preparations. A video camera directed to the driver position was recording images of the driver's upper body parts, including the face, and the images were analyzed with respect to features of significance to the breathing behavior and breath detection, such as mouth opening and head direction.RESULTS:Improvement of the sensor system with respect to signal resolution including algorithm and software development, and fusion of the sensor and camera signals was successfully implemented and tested before starting the human study. In addition, experimental tests and simulations were performed with the purpose of connecting human subject data with repeatable experimental conditions. The results include occurrence statistics of detected breaths by signal peaks of CO2 and alcohol. From the statistical data, the accuracy of breath alcohol estimation and timing related to initial driver routines (door opening, taking a seat, door closure, buckling up, etc.) can be estimated. The investigation confirmed the feasibility of passive driver breath alcohol detection using our present system. Trade-offs between timing and sensor signal resolution requirements will become critical. Further improvement of sensor resolution and system ruggedness is required before the results can be industrialized.CONCLUSIONS:It is concluded that a further important step toward completely passive detection of driver breath alcohol has been taken. If required, the sniffer function with alcohol detection capability can be combined with a subsequent highly accurate breath test to confirm the driver's legal status using the same sensor device. The study is relevant to crash avoidance, in particular driver monitoring systems and driver-vehicle interface design.

Breath alcohol screening is important for traffic safety, access control and other areas of health promotion. A family of sensor devices useful for these purposes is being developed and evaluated. This paper is focusing on algorithms for the determination of breath alcohol concentration in diluted breath samples using carbon dioxide to compensate for the dilution. The examined algorithms make use of signal averaging, weighting and personalization to reduce estimation errors. Evaluation has been performed by using data from a previously conducted human study. It is concluded that these features in combination will significantly reduce the random error compared to the signal averaging algorithm taken alone.

In screening applications there is a need for improved breath alcohol analyzers. Accuracy, specificity, usability, and through-put are critical to the device performance. Objective: To characterize the critical performance of a new contactless breath alcohol analyzer. Methods: The device is characterized by measurements using artificial breath gas and human subjects. Breath sampling is performed in ambient air using carbon dioxide as a biomarker. Results: Resolution and inter-individual variation, response time, and specificity were shown to meet the requirements of industrial standards. The feasibility of contactless measurement was demonstrated. Conclusions: The new device exhibits sufficient performance in moderately diluted breath samples. Further work is underway to reach the objective of unobtrusive breath alcohol analysis.

The study objective was to evaluate a novel method and technology for unobtrusive determination of breath alcohol in relation to current industrial accuracy standards. The methodology uses carbon dioxide as a tracer gas detected by sensor technology based on infrared spectroscopy. Part one of the investigation was to analyse the performance of hand-held prototype devices and included tests of resolution, unit-to-unit variation during calibration, response to alcohol containing gas pulses created with a wet gas simulator, and cross sensitivity to other substances. In part two of the study, 30 human participants provided 1465 breath tests in both unobtrusive and obtrusive use modes. The results of both parts of the study indicate that the prototype devices exceeded present industrial accuracy requirements. The proposed methodology and technology eliminate the previous contradiction between unobtrusiveness and high accuracy.

The study objective was to evaluate a novel method and technology for unobtrusive determination of breath alcohol in relation to current industrial accuracy standards.The methodology uses carbon dioxide as a tracer gas detected by sensor technology based on infrared spectroscopy.Part one of the investigation was to analyse the performance of hand-held prototype devices and included tests of resolution, unit-to-unit variation during calibration, response to alcohol containing gas pulses created with a wet gas simulator, and cross sensitivity to other substances.In part two of the study, 30 human participants provided 1465 breath tests in both unobtrusive and obtrusive use modes.The results of both parts of the study indicate that the prototype devices exceeded present industrial accuracy requirements.The proposed methodology and technology eliminate the previous contradiction between unobtrusiveness and high accuracy.

The reported work is highly related to the DADSS (driver alcohol detection system for safety, [3]) program, and other related initiatives aiming at the prevention of drunk driving. The possibility of breath alcohol estimation in highly diluted breath samples in a vehicle cabin by using carbon dioxide as a tracer gas to compensate for the dilution has been demonstrated and evaluated elsewhere [4-12]. The infrared sensor technology developed by SenseAir AB, Sweden, is enabling unprecedented sensor performance [9]. However, passive breath alcohol detection requiring no cooperation from the driver has remained a major technological challenge. The aim of the present investigation is to obtain experimental proof-ofprinciple of completely passive, in-vehicle estimation of breath alcohol concentration. A prototype sensor system has been integrated with the casing of the upper steering column within a vehicle. Human subjects, some of them intoxicated by alcohol, are instructed to enter the vehicle and perform a simulated driving task while breathing normally. Sensor signals corresponding to alcohol and CO2 concentration at the sensor position are recorded and analyzed off-line. The sensor CO2 signal pattern includes peaks corresponding to increasing CO2 concentration in expired air reaching the sensor position after leaving the subject’s mouth or nose. These peaks will coincide with peaks in the alcohol signal from an intoxicated subject. From the peak magnitudes an algorithm for breath alcohol estimation has been devised. The results indicate that peaks from normal breathing are readily detectable and quantifiable by the sensors, although the dilution factor DF (ratio between expired and actual concentration measured by the sensor) may be as high as several hundred at the steering column sensor position.