Non-invasive detection of alcohol concentration based on photoplethysmogram signals

Sobriety test, which commonly uses a breathalyser for estimating blood alcohol content (BAC) from a breath sample, is commonly used to detect drunk driving. The detection often gives rise to sanitary concern and violation of human right. This research proposes a new method that employs non-invasive measurement of photoplethysmography (PPG) signal for detecting BAC of the test subject under the sobriety test. The PPG signal is measured via an LED transmitter and a receiver that illuminates finger and measures the changes in lighting. Since a PPG signal contains information of systolic and diastolic blood pressure, it is possible to be used for the purpose of detecting BAC. The authors have developed a practical alcohol sobriety test system to analyse the status of alcohol intake of the subject. Extensive tests have been conducted to examine feasibility of the proposed system with an identification rate up to 85%.