The DRAFT Experiment will read the air quality across an air filter. This experiment has been designed by The Spring Institute for Forest on the Moon.
Engineering: Jorge Galván Lobo
Science: Patrick Grove
Electronics: Álvaro Ropero López
1x Raspberry PI 3 (Sensor Computer)
2x Arduino Nano (Sensor controller)
2x SGP30 Gas Sensor
2x MQ135 Gas Sensor
2x MQ3 Gas Sensor
2x MQ7 Gas Sensor
A Sensor Suite is composed of one of each sensor, connected to one Arduino Nano controller.
One Sensor Suite will be place at each end of the Air filter, to measure the difference in Air Quality after filtering.
The MQ sensors are operated in Arduino using the library MQUnifiedSensor\ https://www.arduino.cc/reference/en/libraries/mqunifiedsensor/
The SGP30 sensor is operated in Arduino using the library SparkFun_SGP30\ https://github.com/sparkfun/SparkFun_SGP30_Arduino_Library
- Install Arduino IDE.
- Open the Arduino_SensorSuite.ino file.
arduino- Upload the file into both Arduino Nano, on its respective port.
- Calibrate the MQ Sensors (see below).
- Execute SensorReading python script on Raspberry Pi.
- It will appear a file named sensor_data.csv which contains the data logged from the sensors.
- Once the data is collected, the python script Plot_sensor_data can be used to visualize the data.
MQ Sensors require calibration. Before starting any work, you should power your sensor and let it burn for at least 24 hours. This step is very important because MQ sensors come polluted, and burning helps them to clean themselves. You have to power the sensors with 5V and put them In a clean place.
Since the heater of the sensor draws a lot of current and the sensor needs 5V to work properly, it is better if you use an external power supply that assures you a voltage input of 5V with enough current for the heater (The Arduino provided a little less than 4.6V when tested). The Arduino Mini Pro has an internal 5V regulator, so you can connect an external power supply (no more than 12V) to the Raw pin. Alternatively, this tutorial shows you how to setup a 5V regulated power supply: https://www.jaycon.com/understanding-a-gas-sensor/
For Calibration, open Arduino_SensorSuite.ino and follow the instructions You can do so by placing your cursor in front of the second line in this snippet and pressing Ctrl+/
//While calibrating Your sensor Uncomment this calibration portion and calibrate for R0.
/***************************** MQ CAlibration ********************************************
Then upload the file to the Arduino Nano controller and open the Serial Monitor (Ctrl+Shift+M) and wait until calibration is complete. Repeat this process for both Sensor Suites.
The first 10-20 readings will always be eCO2 400 ppm TVOC 0 ppb . That's because the sensor is warming up, so it will have 'null' readings. The SensorReading script will omit the first 20 lines of readings for this reason.
The Spring Institute for Forest on the Moon