For any workplace, a clean and safe environment is all we need. And, factors like alcohol and ethanol gases make an unhealthy impact at the workplace. And, that’s why you have seen that many organizations make the other rooms for smoking because it is highly unacceptable to do these activities in cooperate environment. So, to detect alcohol, ethanol, or smoke MQ3 sensor is a great deal.
An Overview about MQ3 Sensor
The MQ3 sensor module is convenient for detecting Alcohol, Methane, Hexane, Carbon monoxide, liquified petroleum gas (LPG). The sensor contains tin dioxide. When the alcohol gas exists around, the conductivity of the sensor is higher. MQ3 gas sensor has an acute sensitivity to Alcohol and has excellent resistance to disturb smoke, vapor, and gasoline.
Internal Structure of MQ3 sensor
They enclose the sensor in two layers of fine stainless steel mesh which is known as an Anti-explosion network. It assures that the heater element inside the sensor will not cause an explosion. The sensing element forms the star-shaped structure. Six connecting legs expand beyond the Bakelite base. From those six legs, two leads heat the sensing element and are connected through the well-known collective alloy called Nickel-Chromium coil. The remaining four legs are actually responsible for output signals. They made the sensing element from Aluminum Oxide (AL2O3) and have a coating of Tin Dioxide (SnO2), which is sensitive to Alcohol and other gases.
Working Principle
Inside, the sensor holds the resistance across two points. On the disclosure of alcohol, the sensor detects it and therefore this resistance varies. Higher the level of the alcohol, the lower the resistance would be. And, the smaller the resistance of the sensor, the higher the voltage reading would be. Hence, the alcohol is tested by measuring this resistance. The sensor and load resistor together build a voltage divider.
Features and Specifications of MQ3 Sensor
Features:
- Sensor Type – Semiconductor
- Easy SIP header interface
- Compatible with most of the microcontrollers
- Low-power standby mode
- Requires heater voltage
- Good sensitivity to alcohol gas
- Fast response and High sensitivity
- Long life and low cost
- Requires simple Drive circuit
Specifications
- 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
- Detecting Concentration: 0.05-10mg/L Alcohol
- Interface: 1 TTL compatible input (HSW), 1 TTL compatible output (ALR)
- Heater consumption: less than 750mW
- Operating temperature: 14 to 122 °F (-10 to 50°C)
- Load resistance: 200kΩ
- Sensitivity S: Rs(in air)/Rs(0.4mg/L Alcohol)≥5
- Sensing Resistance Rs: 2KΩ-20KΩ(in 0.4mg/l alcohol)
- Dimensions: 32 x 22 x 16 mm
Pinout of MQ3 Sensor
| Pin Name | Description |
| Vcc | Power Pin requires an operating voltage of 5V. |
| GND | Ground pin. |
| DO | Digital out the pin, to get the digital output from the sensor, need to set the threshold value using Pot. |
| AO | Analog out the pin. It based the output of this pin on the intensity of the gas. |
Applications
Environmental Monitor
The environmental monitoring device can provide a sufficient monitoring method that uses an MQ3 sensor. This is a lightweight, customer-friendly, and low-cost air monitoring device that can measure Methane gas we can use this anywhere
Alcohol Testing/Detecting Devices
Using this system, we can immediately collect information about alcohol, ethanol, and can also display the gases which can be handled by any microcontroller, and the results on the OLED display.
Breathalyser
A breathalyzer is a device used for detecting blood alcohol content from a breath sample. This means the device can estimate the volume or amount of alcohol from your breath. In various countries, this device becomes very effective because of several cases of accidents happened by drunk drivers.
