Different kinds of smoke sensors
Flammable Gas and Smoke Sensor
MQ2 is a low cost semiconductor sensor which can detect smoke and flammable gases at concentrations from 300 to 10,000 ppm. The sensitive material used for this sensor is SnO2, whose conductivity is lower in clean air. It’s conductivity increases as the concentration of combustible gases increases. This sensor has high sensitivity to Hydrogen, Propane, LPG, Methane and other combustible steams. This can be used to detect gas leakage in industries and houses. MQ2 gas sensor can be easily interfaced with Microcontrollers, Arduino Boards, Raspberry Pi etc using an Analog to Digital Converter (ADC).
Optical Smoke & Dust Sensor
GP2Y1010AU0F is a commonly used Optical Dust Sensor in air purifier systems to detect very fine dust particles like cigarette smoke in air. It consists an infrared emitter and a phototransistor which are diagonally arranged to detect reflected light from dust. The sensor is very compact and has a very low current consumption. By using this module we can easily detect the presence of dust by the photometry of only one pulse. It can also distinguish smoke from house dust by pulse pattern of output voltage.
Smoke and Flammable Gas Sensor
This sensor module is made using MQ2 Smoke and Flammable Gas Sensor, which uses Tin oxide (SnO2) as the sensor element. Tin oxide has a lower conductivity in clean air. When it comes in contact with flammable gases like LPG, hydrogen, butane, propane, alcohol, smoke and other combustible gases its conductivity increases. This module uses a simple circuit to measure changes in conductivity and output the same. It has dual signal output ie. analogue output and TTL level output. The module also provides a potentiometer to adjust the sensitivity of the sensor.