An Overview about MQ303A Alcohol Sensor
The MQ303A sensor module is favorable for detecting Alcohol 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
They made the tabular sensing part of the sensor from aluminum oxide which has a coating of tin dioxide(SnO2). When this layer of SnO2 is heated at a high temperature, oxygen gets adsorbed at the surface. So, when there is no alcohol, the electrons from the conduction band of SnO2 get attracted towards the oxygen. Thus, this forms the depletion layer below the surface of the SnO2. Hence, worked as a potential barrier that allows no current to flow.
Working Principle
When the layer senses the alcohol, oxygen is reacted with the alcohol, and the density of adsorbed oxygen gets decreased. This reduces the potential barrier and electrons are allowed to release into SnO2. As a result, the current starts to flow in a sensor.
Features and Specifications of MQ303A
Features
- High sensitivity
- Fast response and resume
- long life and low cost
- Mini size
Specifications
- Power requirements: 5 VDC @ ~120 mA (heater on)
- Detection Gas: Alcohol
- Concentration: 20-1000ppm Alcohol
- Interface: 1 TTL compatible input (SEL), 1 TTL compatible output (DAT)
- Dimension: 40 x 20 x12 mm
- Heater Voltage: 0.9V / 0.1V AC or DC
- Heater Current: 120 20mA
Pinouts of MQ303A 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 of MQ303A
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 Level Tester
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.
Breathalysers
They are the devices that estimate the alcohol taken by a person. Mainly, helps to warn a drunk driver to avoid accidents. Thus, these breathalyzer devices use an Alcohol sensor. We used a breathalyzer 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.
