MQ-135 Gas Sensor Module | Air Quality & Hazardous Gas Detection | For Arduino

The MQ135 is a sensor module that can detect different types of air pollution. It's meant for checking air quality with microcontrollers like Arduino or ESP32. The module gives an analog voltage output that changes based on how much gas is in the air around it. Features and Benefits - Wide detection range - This gas sensor module can sense ammonia, NOx, alcohol, benzene, smoke, and CO2. - Adjustable sensitivity - A knob on the board lets you set the digital output's trigger point to fit your specific needs. - Dual analog and digital outputs - Use the analog pin for exact concentration readings or the digital pin for a simple on/off alert. - Fast response time - The sensor reacts quickly to changes in air makeup, giving you timely data for your project. Applications - Indoor air quality monitoring systems to check for VOCs (volatile organic compounds). - Environmental sensing stations that record air pollution data over time. - Workshop or garage safety alarms to warn about smoke or dangerous fumes. What You Need Before testing your gas sensor, gather the necessary tools. You will need a multimeter capable of measuring microamperes (µA) for accurate readings of active signal strength. Ensure your multimeter has fresh batteries to prevent inaccurate measurements. A small screwdriver may also be useful for accessing wiring terminals. Always consult the gas sensor's specific wiring diagram or installation guide, if available, to understand its connections and expected operational parameters. Understanding how an electrochemical gas sensor works involves its ability to detect specific gases through a chemical reaction that produces an electrical signal, which your multimeter will measure. Method 1: Testing Active Signal Strength ($\mu\text{A}$) This method focuses on measuring the electrical output of your gas sensor, specifically the MQ-135 Gas Sensor Module, to assess its active signal strength. A healthy gas sensor will produce a measurable electrical current when exposed to the target gases. This test is crucial for verifying the sensor's functionality and ensuring it can accurately detect hazardous gases. If you are testing a flame sensor on a gas furnace, the principle of measuring active signal strength remains similar, though the specific expected values will differ. This process helps confirm the sensor's ability to respond to its intended environmental changes.