1 A REVIEW PAPER ON ALCOHOL SENSORS Nitin Narahari Hegde 1 , Karthik Mohan Rao 2 , Asst. Prof. Kendaganna Swamy 3 Department of Biomedical Signal Processing & Instrumentation, RVCE, Bengaluru, India 1 nhegde85@gmail.com 2 kmraoudp@gmail.com 3 swamy_knsit@rediffmail.com Abstract— Impaired driving is the cause for most of road accidents all over the world. In India alone around 80000 deaths happen every year due to driving under influence (DUI). While government regulations play an important role in ensuring driver and road safety, Alcohol sensors play an important role in detection of Blood Alcohol level (BAC). This paper provides an overview of detecting BAC through Breath Alcohol Level (BrAL). This paper will outline the approach being taken, and the significant challenges to overcome. Keywords— BAC, BrAL, DUI, Alcohol Detector, Breathalyzer, Intoxilyzer, Alcosnsor, Dual Detector, Spectroscopy I.INTRODUCTION We hear and read about drivers involved in an accident who are later charged with drunken driving, and usually a news report on the accident will driver's blood alcohol level was more legal limit for blood alcohol level. Impaired driving is the cause for most of road accidents all over the world. In India alone around 80000 deaths happen every year due to driving under influence (DUI). Alcohol intoxication is legally defined by the blood alcohol concentration (BAC) level [1]. Law criminalizes driving with a blood alcohol concentration over 0.08g/mL. However taking a blood sample in the field for later analysis in the laboratory is not practical or efficient for detaining drivers suspected of driving under the influence (DUI) [1,6]. Urine tests for alcohol proved to be just as impractical in the field as blood sampling. What was needed was a way to measure something related to blood alcohol concentration without invading a suspect's body [1, 9]. So Inventors focused on developing instruments to measure and breath-alcohol levels. Today, law enforcement officers and prosecutors around the world rely on breath alcohol testing to investigate and/or prove their DUI cases. There are a variety of alcohol detectors present used by law enforcement officers for effective alcohol detection. Alcohol detectors measure the Blood Alcohol Content by indirectly measuring alcohol in person's breath. The three major types of alcohol detectors are Breathalyzers, Intoxilyzer, and Alcosensor and Dual detectors [1, 9]. II. HISTORY In the early 1930s, impaired driving became a national issue in USA. However, the legal and scientific communities were ill equipped to address the burgeoning problem. In1927 Dr. Emil Bogen reported BAC by analyzing a person’s breath. In 1938, Dr. R. L. Holcomb conducted further research into the risks associated with drinking alcohol and driving using the Drunkometer, a breath-testing instrument invented by Professor Rolla Harger [1]. In1954 Dr. Robert Borkenstein invented the first truly practical breathtesting instrument, the Breathalyzer. In the mid-1960s, Borkenstein and others utilized the instrument in the important and widely publicized Grand Rapids study, which corroborated Holcomb’s study and demonstrated that at a breath alcohol concentration (BrAC) of 0.08 and above the likelihood of causing a motor vehicle crash increases significantly. In the 1970s, Mr. Richard Harte invented the first breath alcohol testing instrument employing infrared spectrometry [1]. III. ANATOMY OF A BREATH SAMPLE Anatomy of a Breath Sample To better understand breath- testing devices, one must have a basic understanding of human physiology and alcohol pharmacology. Alcohol typically enters the body through oral ingestion of a beverage containing ethyl alcohol. Alcohol enters the bloodstream through the stomach and small intestine by simple diffusion [1,8]. Blood transports the alcohol, which is infinitely water soluble, to the bodily tissues. Veins carry the blood to and through the lungs where the blood becomes oxygenated. Arteries then carry the oxygen-rich blood to the brain and the rest of the body [1,8]. Lung tissue is made of air pockets, or alveoli, surrounded by blood-rich membranes. A fraction of the alcohol circulating in the blood crosses the membranes and evaporates into the alveoli. During exhalation, air is forced out of the alveoli and ultimately emerges from the lungs into the person’s breath.