Self-Powered and Cost-Effective Wireless Sensor Node for Air Quality Monitoring With an Optically Transparent Smart Antenna System
Air pollution poses a significant global threat, particularly in developing regions, affecting public health and economic stability more severely than in developed areas. Existing fixed weather stations (FWSs) are costly, difficult to install, and often too sparse to capture localized pollution events. At the same time, emerging low-cost devices fail to provide comprehensive monitoring for massive outdoor deployments. This study presents a breakthrough solution: a dodecahedron-shaped, wireless sensor node that is both cost-effective and self-powered, designed for easy deployment across diverse urban landscapes.
The sensor node incorporates a novel system of optically transparent microstrip patch antennas that can adjust the node’s radiation pattern to minimize electromagnetic pollution and maximize energy efficiency. The prototype is made using cost-effective additive manufacturing, with silver ink applied via screen printing onto PMMA substrates. This method ensures mass production capability. Each face of the dodecahedron is laser-cut, masked with Kapton tape, and printed with metallic meshes.
These antennas, boasting 87% transparency, are strategically integrated atop modular solar panels. This integration ensures the nodes are self-sustaining and achieve a significant size reduction—80% smaller than an equivalent planar array. Operating within the 2.4 GHz ISM band, the antennas improve the node’s communication capability, with gain enhancements of up to 14.8 dB in specific directions, facilitating robust data transmission over extended ranges.
The prototype has been tested in urban, industrial, and rural settings. In urban areas, its performance was compared to an FWS and a commercial handheld reference (CHR) from Aeroqual, demonstrating its adaptability even in areas with limited monitoring infrastructure.
Field tests have proven that extensively deploying these cost-effective sensor nodes can dramatically improve air quality maps' resolution, outperforming sparse FWS installations. For example, the sensors detected nitrogen dioxide (NO2) levels as high as 85.3 ppb at a bus stop location, dramatically exceeding the 7.52 ppb measured by an FWS just 1.1 km away. This stark contrast highlights the sensors' ability to identify pollution hotspots, capturing spikes linked to vehicle traffic and illustrating their precision in detecting transient pollution sources—key for analyzing urban pollution patterns.
The sensors measure environmental parameters such as temperature and humidity with considerable accuracy, displaying significant deviations from FWS readings and enriching our understanding of localized air quality and microclimatic conditions. The system’s scalability supports the formation of dense, cost-effective networks capable of delivering high-resolution air quality maps. These networks can improve urban air quality management, thus contributing to cleaner and healthier environments.
This design minimizes electromagnetic pollution and utilizes solar panels beneath each antenna to capture energy efficiently. The prototype outperforms existing systems in recording localized air quality data and has shown reliable performance in various environments, proving its potential for widespread deployment. With smart antenna integration, this sensor node offers a robust and cost-effective solution for high-resolution air quality monitoring, enabling comprehensive air quality mapping in IoT applications.