The MQ-3 alcohol sensor is a semiconductor-based device designed to detect alcohol vapors (specifically ethanol) in the air, with high sensitivity ranging from 25 to 500ppm. Commonly used in breathalyzers and safety devices, it operates by altering its conductivity in the presence of alcohol, providing both analog and digital output signals.�
It can detect the 25-500ppm alcohol gas concentration. If the target gas is present in the air, the resistance of the semiconductor material is enhanced with the rise in gas concentration.
The structure is designed in such a way that it has a high sensitivity to alcohol. Moreover, it has good resistance to gasoline, smoke, and vapors.
The following gases are possible to detect using an MQ-3 alcohol sensor: Ethanol (primary target gas), Aromatic hydrocarbons(Toluene, Benzene, Xylene), Chlorinated hydrocarbons (Trichloroethylene, Dichloromethane, Amines)
Power requirements: 5 VDC @ ~165 mA (heater on) / ~60 mA (heater off)
Current Consumption: 150mA
DO output: TTL digital 0 and 1 ( 0.1 and 5V)
AO output: 0.1- 0.3 V (relative to pollution), the maximum concentration of a voltage of about 4V
Aluminum oxide (AL2O3) ceramic with a tin dioxide coating (SnO2). is used in the form of a tubular structure and is known as the sensing element. It is important to notice that tin oxide is the most important element here because it is sensitive to alcohol, which is the basic purpose of this sensor. The role of aluminum oxide is to improve efficiency and heat sensitivity. It maintains the continuous heating of the system and, as a result, helps in efficient results.
There is a resistance across an A and B inside the sensor which varies on detection of alcohol. More the alcohol, the lower the resistance. The alcohol is measured by measuring this resistance. The sensor and load resistor form a voltage divider, and the lower the sensor resistance, the higher the voltage reading will be.
MQ-3 module is suitable for detecting Alcohol, Benzine, CH4, Hexane, LPG, CO. Sensitive material of MQ-3 gas sensor is SnO2, which with lower conductivity in clean air. When the target alcohol gas exist, the sensor’s conductivity is more higher along with the gas concentration rising. MQ-3 gas sensor has high sensitity to Alcohol, and has good resistance to disturb of gasoline, smoke and vapor.
This sensor provides an analog resistive output based on alcohol concentration. When the alcohol gas exist, the sensor’s conductivity gets higher along with the gas concentration rising.
The sensor requires a warm-up time to function accurately. It is important to calibrate the sensor for specific applications to achieve accurate measurements.
