Arduino Combustion Gas IOT Monitor

This project is about using sensors coupled with the Arduino IOT cloud, to study combustion gas products in the environment. Before this project, I began measuring environmental properties like temperature, humidity, and pressure. There are many applications documented for these variables and the carrier board also has these sensors built in for your use. Monitoring these variables in my home allowed me to learn about the dynamics of air quality in my environments. As an example, elevated humidity allows mold to grow, leading to air quality problems that can become health problems if not addressed. I chose to monitor Carbon monoxide (CO), and Carbon dioxide (CO2) for this project. CO2 is naturally present in the atmosphere at around 400 ppm (parts per million). Humans and animals produce CO2 as food is converted to energy. CO2 is also involved extensively in other biological systems, being present in soil, rock, and water, as well as the air. Plants take up CO2 for growth, and fortunately for us, release Oxygen in the process. Combustion of fuels generates CO and CO2. How the fuel is burned affects the amount of CO produced considerably. Elevated CO2 levels in fresh air indicate an air quality issue that should be investigated and corrected. Elevated levels of CO can come from a lack of fresh air, inadequate ventilation, and/or incomplete combustion. When CO is inhaled, it inhibits the body’s ability to transport Oxygen. CO inhalation can be deadly. Many lives are lost each year due to CO inhalation. The sensor in this project is intended to trend changes in CO and is not intended to be used for safety critical monitoring applications. CO detectors that are designed to alarm when CO levels have become life threatening are now available in many stores. They are becoming more common in homes, integral to, or alongside of smoke detectors. As CO and CO2 measurements become more available to scientists and medical experts, there is growing evidence of health effects of long-term exposure to elevated levels of CO and CO2. There are many publications regarding the health effects of carbon monoxide. This is one example: https://www.euro.who.int/__data/assets/pdf_file/0020/123059/AQG2ndEd_5_5carbonmonoxide.PDF

Carbon Dioxide levels in buildings are usually indicative of the amount of fresh air that is being exchanged. Elevated levels of Carbon Dioxide can also be harmful as reported here: https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm#:~:text=Exposure%20to%20CO2%20can%20produce, coma%2C%20asphyxia%2C%20and%20convulsions.

The graph showing CO levels was taken from a parking area where vehicles were coming in and out over about an hour.

One finding I have made in these experiments is that there are different sensors that report the ability to measure gases like CO and CO2. The way these sensors respond can vary considerably as shown in the figure that trends CO2 results for four different CO2 sensors. The CO2 concentrations reported from some sensors is not measured but calculated from other properties and does not accurately reflect the true CO2 concentration. Here is an example of data I collected from 4 different sensors that all reported CO2.

The Arduino team graciously provided an OPLA kit to assist me with this project. I am finding the OPLA kit is very thoughtful product. It has everything you need to get started in IOT projects. There are on-board sensors, switches, LEDs, display, battery holder, I/O cables for external sensors, and a nice case. The kit documentation will get you up and running quickly and offers several projects to help you learn. I recommend taking the time to get up and running with the built-in projects before moving on. There are also some very cool projects using the kit out on the project hub. An Arduino IOT carrier board provides many features. In this project, the display, the robust case, and the simple connections between the carrier and the sensors were utilized. In future iterations, I would like to use the switches to be able to select different internet connections, to initiate calibration sequences, and to use the on-board relays to trigger events to improve the air quality. The on-board SD card could also be used for data logging whether connected to the IOT cloud or not. I have used it in both stationary and mobile measuring situations. My objective was to learn about the air quality of my environment that I live in, travel through, or occupy on occasion. Here is the desktop view of this project.

A separate board was built to contain the sensors, and these are cabled to the IOT carrier board. Communication with the CO sensor was done by measuring an analog signal on the sensor, which is proportional to the CO concentration. Communication with the CO2 sensor is done using the I2C protocol. Basic code was inserted into the Arduino IOT platform to upload sensor data to the cloud. Additional code was written to remotely (via the cloud) enable or disable the IOT carrier display. Calibration of the sensors with standards will be attempted in future experiments.

This project has also been helpful for me to learn more about the internet of things (IOT), microcontrollers, and programming. I acknowledge and appreciate those who have shared their experience and wisdom on these topics. Feedback is welcome. I have found the Arduino IOT tools to be very helpful.