Alcohol detector sensor

In theory, the most accurate way to determine whether a person is drunk driving should be to check the alcohol content in the driver's blood, but this method is not easy to implement in actual law enforcement.

However, since alcohol is absorbed by the body through the digestive system after drinking, and about 90% of the alcohol is expelled through the lungs through blood circulation, therefore measuring the alcohol content in the exhaled breath can also determine whether the person is drinking.

According to the national standard GB19522-2010, the breath alcohol content of vehicle drivers is converted into blood alcohol content according to the ratio of 1:2200, that is, the breath alcohol content multiplied by 2200 equals the blood alcohol content value.

Based on this, most countries around the world currently use alcohol sensor breathalyzer to conduct on-site testing of drivers to determine the alcohol content in the person being measured. Currently commonly used alcohol testers are divided into two categories: fuel cell type (electrochemical type) and semiconductor type.

Fuel cell type (electrochemical type) Alcohol detector sensor

The fuel cell breath alcohol tester uses a fuel cell Alcohol detector sensor as the gas sensor. It is an electrochemical type, so it is also called an electrochemical type.

The fuel cell Alcohol detector sensor uses the precious metal platinum as the electrode. Alcohol and oxygen undergo corresponding oxidation-reduction reactions on the working electrode and counter electrode and release charges to form a current. The size of the generated current is proportional to the alcohol concentration and follows Faraday's law. The alcohol concentration can be determined by testing the size of the current.

Semiconductor type Alcohol detector sensor

The gas-sensitive material used in the semiconductor type is tin dioxide (SnO2), which has low conductivity in clean air. When alcohol vapor is present in the environment where the Alcohol detector sensor is located, the conductivity of the gas sensor changes with the concentration of alcohol gas in the air. increases with the increase. A simple circuit can be used to convert changes in conductivity into an output signal corresponding to that gas concentration.

The semiconductor type has the characteristics of compact size, low cost, and long life, while the fuel cell type has the characteristics of low power consumption, high precision and sensitivity.

The difference in application between the two

The biggest advantage of the semiconductor alcohol detector sensor is its low price, which is only a fraction of the fuel cell type. However, the accuracy is not as good as the fuel cell type, so it is usually used in situations with low requirements, such as self-testing or general qualitative testing. detection.

As for human body alcohol content detection as a basis for law enforcement or punishment, a fuel cell-type Alcohol detector sensor that can meet relevant standards should be used to improve accuracy and law enforcement efficiency.

As usage scenarios and application requirements continue to change, Alcohol detector sensors will also be used in various consumer electronic products, which puts forward higher demands for miniaturization and integration of sensors. Alcohol detector sensors made using MEMS technology have the characteristics of small size, low power consumption, high sensitivity, fast response recovery, simple drive circuit, good stability, and long life. They are used in detection applications in consumer products such as mobile phones/computers. It is also widely used in alcohol vapor in the workplace, drunkenness supervision of motor vehicle drivers and other dangerous workers.