Well-being, concentration, and health largely depend on the quality of the air inhaled every day at home and at work. Contaminants invisible to the naked eye are responsible for causing many unpleasant ailments, including headaches, respiratory diseases, irritation of the mucous membrane and eyes, allergies, and skin problems. In extreme cases, inadequate air quality control can contribute to serious illness ending in heart failure or cancer.
The device we developed was designed for consumer use in a residential environment, but due to the rich range of measurement possibilities and high resistance to dust, moisture, and temperature, it is also perfect for harsh industrial buildings. A wide range of measured values allows you to check the quality of extremely polluted air, and the additional function of controlling the concentration of oxygen and carbon dioxide allows you to ensure the safety of combustion processes and preliminary monitoring of exhaust emissions.
- Particulate Matter (PM) content. The numerical designation specifies the maximum particle diameter of the group:
- PM2.5 – the most dangerous for health,
- Oxygen and CO2 concentration.
- The occurrence of Volatile Organic Compounds (VOCs).
A broad range of the functionalities
The device has implemented an intelligent energy-saving mode. Among other things, thanks to the use of Bluetooth Low Power (BLE) technology, power consumption has been optimized, guaranteeing a very long battery life. The air control station reduces the frequency of measurements and goes into sleep mode, while only data selected by the user are sent during data recording. The charging system with μUSB and USB type C connectors is adapted to 5V voltage and current in the range 1-3A.
The measuring station operates in three basic modes of data transmission. Two of them are based on saving measurements in the cloud:
Direct connection – the device connects to the Internet using the integrated WiFi module.
Indirect connection – based on a Bluetooth module communicating with an additional BT-IP access gate, we achieve an effect similar to the above, but we increase energy savings.
Offline mode – Built-in SD/USB external memory slot allows you to collect measurement history where there is no internet connection.
In addition to the basic tasks, the device provides access to weather forecasts and predicted outdoor air quality thanks to integration with Weather API extensions. In addition, the station informs the user about current RCB alerts on climate, weather and epidemiological threats.
Configuration of the equipment is carried out from the level of the mobile application (Android/iOS) or desktop (MS Windows) without the need to connect the mobile device/computer to a shared local network. The mobile application also allows you to program your own events to trigger the alarm system with modulated intensity of sound and optical signals. Digital outputs for controlling external active filters, among others for popular systems using HEPA filters, will allow you to react immediately. The algorithm for measuring data analysis developed by us based on the recommended parameters of the expected air quality fully automatically manages the operation of many air conditioners, dehumidifiers, and purification devices available on the market.
The technology we used
The central system implementing the correct operation of the device is the WROOM-32 module from Espressif. Using the I2C interface, it communicates with a group of systems equipped with air quality transducers. Sensors using optical elements, photoelectric effect, and the properties of gas mechanics are carefully selected integrated circuits of the best manufacturers tested many times. The module is equipped with a PCB antenna adapted for wireless WiFi and BT/BLE communication.
240 MHz dual-core microcontroller
Bluetooth v4.2 BR/EDR
Low Energy Bluetooth BLE
Wi-Fi protocol in the 802.11 standard
Network protocols: IPv4, IPv6, SSL, HTTPS/FTP/MQTT
A very important aspect of the project was to provide precise measurement of quantities describing air quality while minimizing production costs. Optimization of solutions and selection of the final configuration is the result of the cooperation of engineers specialized in various fields. Another significant parameter of the device is its work culture, which was ensured by the installation of a noiseless fan responsible for injecting the tested air.