An alcohol tester is an instrument used to detect the alcohol content in a person's exhaled breath. It is often used to determine whether an individual has been drinking, especially in the fields of traffic safety, workplace safety, and law enforcement. In this article, we will introduce you to the mainstream alcohol testers.
Development of The Alcohol Tester
The development of the alcohol tester has gone through several stages, dating back to the early 20th century, from the early simple chemical testing methods to modern electronic sensor technology. It can be roughly divided into the following stages:
Early Alcohol Detection Methods
In the early 20th century, the problem of drunk driving gradually attracted attention. Before that, the police and forensic doctors mainly relied on observing the driver's behavior and physical signs to determine whether he was drunk driving, and there was no standardized alcohol concentration detection method. Such as whether the eyes are congested, whether there is an odor of alcohol, etc. These methods are called field sobriety tests. In the 1920s and 1930s, scientists began to study the relationship between alcohol content in breath and alcohol content in blood. Swedish pharmacologists Göran Liljestrand and Paul Linde published a study on alcohol content in exhaled air in 1930. The study showed that the alcohol content in the blood can be measured by breathing, confirming the connection between exhaled breath and blood alcohol concentration, and laying a theoretical foundation for the subsequent development of alcohol testers.
The First Generation of Alcohol Detectors
In 1938, Rolla N. Harger of Indiana University in the United States invented the "Drunkometer", a device based on wet chemistry principles, which monitors drivers by linking breath alcohol content (BrAC) with blood alcohol content (BAC), marking the birth of the first generation of alcohol detectors. This method involves oxidizing the exhaled alcohol gas through potassium permanganate. The concentration of alcohol is inferred based on how quickly the solution fades. This chemical reaction also causes the resistance inside the instrument to change, so the accurate value can be obtained by computer calculation. It was adopted by police departments across the United States in 1940.
The Second Generation of Alcohol Detectors
In the 1950s, with the popularization of automobiles, traffic accidents caused by drunk driving surged, prompting people to develop more effective alcohol testing tools. In 1953, Dräger first put the alcohol test tube on the market, a rapid test device that determines whether the driver is under the influence of alcohol through a single breath. The test results are quick and easy to understand, and it was soon accepted by legal authorities in many countries.
Application of Electronic Sensor Technology
In the 1970s and 1980s, manufacturers such as Dräger began to develop alcohol detectors based on electronic sensors, such as infrared sensors and electrochemical sensors. These new technologies provide faster and more accurate test results, promoting the technological advancement of alcohol testers.
Modern Alcohol Testers
The current mainstream alcohol testers are mainly fuel cell type (electrochemical method) breath alcohol testers and semiconductor type breath alcohol testers. Semiconductor sensors are low-cost, simple to manufacture, and highly sensitive, making them suitable for people to test independently. With the continuous innovation of technology, modern alcohol testers have higher accuracy, stability, and convenience. They usually integrate microprocessors and advanced sensor technology, can display alcohol concentration in real-time, and have data storage and transmission functions.
After the evolution from simple field sobriety tests to modern electronic sensor tests, the continuous innovation of technology and the continuous expansion of applications have made alcohol testers play an increasingly important role in ensuring public safety, and people's understanding of the problem of drunk driving has continued to deepen.
How dose a fuel cell alcohol tester works?
A fuel cell alcohol tester (also called an electrochemical alcohol tester) is a device that assesses the alcohol content in an individual's blood by detecting the alcohol concentration in the exhaled breath. It is also one of the most commonly used detection methods. When a person exhales, if they have drunk alcohol, the exhaled breath contains alcohol molecules. These alcohol molecules are oxidized into acetaldehyde by a catalyst in the alcohol tester, and this process releases energy, which forms an alcohol value through an ammeter. The higher the concentration of the exhaled alcohol gas, the larger the voltage display number of the tester. Its working principle is based on electrochemical reactions, and the specific steps are as follows:
- Breath sample collection. When the person being tested blows through the mouthpiece of the tester, the exhaled gas sample is delivered to the sensor area.
- Electrochemical reaction. The exhaled gas first passes through a filter device to remove moisture and other impurities. In some designs, the gas may also be heated to ensure that the alcohol in the gas exists in a gaseous state, thereby improving the accuracy of the detection. The sensor contains a fuel cell with a catalyst inside. When the alcohol molecules reach the sensor, they are oxidized by the catalyst, releasing electrons. These electrons flow through an external circuit to form an electric current.
- Relationship between current and alcohol concentration. By measuring the magnitude of the current, the alcohol concentration in the exhaled breath can be determined. The processed gas then enters the fuel cell. The fuel cell usually contains two electrodes: an anode (positive electrode) and a cathode (negative electrode), with an electrolyte membrane between them. At the anode, the alcohol in the exhaled breath reacts chemically with oxygen to produce electrons, nephews, and a small amount of water. The generated electrons cannot pass through the electrolyte membrane, so they can only flow from the anode to the cathode through the external circuit to form an electric current. The strength of the current is proportional to the amount of alcohol passing through the fuel cell.
- Display of results. The electronic equipment inside the tester measures the current generated in the external circuit and converts it into a digital signal through the built-in circuit. The tester calculates the alcohol concentration in the exhaled breath based on the measured current strength and directly displays the alcohol concentration reading on the display. These readings are usually expressed in milligrams per liter (mg/L) or percentage (%), and can be further converted to blood alcohol concentration (BAC).
Fuel cell alcohol testers are widely regarded as law enforcement-level testing equipment due to their high sensitivity, stability, and low cross-sensitivity. Despite their relatively high manufacturing costs, they provide accurate and reliable test results.
Working Principle of Semiconductor Breath Alcohol Detector
Semiconductor breath alcohol detector mainly utilizes the sensitivity of semiconductor materials to alcohol gas. This type of sensor usually contains a sensitive element containing semiconductor material. When the gas containing alcohol contacts the semiconductor surface, the alcohol molecules react with the electrons in the semiconductor to change the conductivity of the semiconductor. This change in conductivity is proportional to the concentration of alcohol. By measuring the change in conductivity, the concentration of alcohol can be calculated.
In semiconductor breath alcohol detectors, a heating element is usually included to heat the sensor to a specific temperature at which the sensor is most sensitive to alcohol. When the heated sensor detects alcohol gas, it responds quickly, and the resulting conductivity change is converted into an electrical signal, which is amplified, filtered, and digitized by the built-in microprocessor. Finally, the microprocessor calculates the alcohol concentration according to a preset algorithm and displays the result on the display.
The advantages of semiconductor breath alcohol detectors are low cost, small size, and suitable for portable applications. However, the accuracy of this type of detector may be affected by environmental factors (such as temperature and humidity), may require a longer warm-up time to reach a stable state, and may be interfered with by other volatile organic compounds (VOCs). Therefore, this type of detector is more suitable for personal use or preliminary screening, rather than law enforcement and other occasions that require high-precision measurement. If you need to buy more relevant test and measurement equipment, the products provided by SISCO online store will be your perfect choice.
