Evaluation of Low-Cost Sensors for Weather and Carbon Dioxide Monitoring in Internet of Things Context

Abstract

In a context of increased environmental awareness, the Internet of Things has allowed individuals or entities to build their own connected devices to share data about the environment. These data are often obtained from widely available low-cost sensors. Some companies are also selling low-cost sensing kits for in-house or outdoor use. The work described in this paper evaluated, in the short term, the performance of a set of low-cost sensors for temperature, relative humidity, atmospheric pressure and carbon dioxide, commonly used in these platforms. The research challenge addressed with this work was assessing how trustable the raw data obtained from these sensors are. The experiments made use of 18 climatic sensors from six different models, and they were evaluated in a controlled climatic chamber that reproduced controlled situations for temperature and humidity. Four CO2 sensors from two different models were analysed through exposure to different gas concentrations in an indoor environment. Our results revealed temperature sensors with a very high positive coefficient of determination (r2 ≥ 0.99), as well as the presence of bias and almost zero random error; the humidity sensors demonstrated a very high positive correlation (r2 ≥ 0.98), significant bias and small-yet-relevant random error; the atmospheric pressure sensors presented good reproducibility, but further studies are required to evaluate their accuracy and precision. For carbon dioxide, the non-dispersive infra-red sensors demonstrated very satisfactory results (r2 ≥ 0.97, with a minimum root mean squared error (RMSE) value of 26 ppm); the metal oxide sensors, despite their moderate results (minimum RMSE equal to 40 ppm and r2 of 0.8–0.96), presented hysteresis, environmental dependence and even positioning interference. The results suggest that most of the evaluated low-cost sensors can provide a good sense of reality at a very good cost–benefit ratio in certain situations.

Site and Season Specific Calibrations Improve Low-cost Sensor Performance: Long-term Field Evaluation of PurpleAir Sensors in Urban and Rural India

“…The BME280 is considered a reliable and accurate low-cost environmental sensor (Araújo et al, 2020). There are occasional sensor miscommunications with the microprocessor, leading to unrealistic values, which we filtered out by restricting RH to 0-100% and temperature to -10-50°C.…”

Design and implementation of 3-D printed radiation shields for environmental sensors

“…The cone or body material provides a UV shield that protects the sensors from solar radiation, and the separation between the plates or the perforations of the body allows airflow to decrease the accumulation of humidity and heat [7] . Seeking to reduce the manufacturing price, some systems have been developed using alternative materials with UV coatings or insulating layers [12] , [4] , [13] , [7] , [14] . In addition, there is now widespread agreement in the literature that the open source scientific hardware is less expensive than proprietary hardware [15] , [16] , [17] , [18] .…”

D3.5 Development of a Low-Cost Sensing Node with Active Ventilation Fan for Air Pollution Monitoring

“…An Arduino microcontroller with similar low-cost sensors used in this project has been used for dense pollution monitoring in foundries [7]. While previous research papers focus on the performance of specific sensors (e.g., [4]) or ready-to-buy-solutions (e.g., [3]), there is little information on the overall manufactured design (e.g., casing) or how important an active ventilation system is.…”

“…According to the datasheet, operating ranges (and accuracies) are -40 to 80 °C (± 0.5 °C) for temperature and 0 to 100% (± 2%) for relative humidity, however [4] indicates that the error for humidity readings is up to 5%.…”