Researchers have introduced innovative temperature and humidity sensors made from paper, emphasizing their accuracy, reliability, and eco-friendliness. The sensors were crafted by printing silver lines on standard paper using a method known as dry additive nanomanufacturing. These sensors work by measuring capacitance changes as the paper absorbs water vapor, reflecting the surrounding humidity levels. Additionally, the sensors record temperature changes through an increase in resistivity of the metallic conductor as temperatures rise. They effectively monitor relative humidity ranges from 20% to 90% and temperature fluctuations from 25°C to 50°C.
Greenhouses and farms open to visitors seeking fresh, locally sourced food are increasingly vital for boosting food production. Farmers are exploring various methods to track environmental conditions to optimize crop growth in greenhouses, and there is also a significant focus on ensuring that harvested food stays fresh during storage. The integration of smart sensor technology to monitor and manage temperature and humidity is crucial in meeting the escalating demand for food for the growing global population.
In the Journal of Laser Applications by AIP Publishing, a research team from Auburn University in Alabama unveiled these paper-based sensors that are not only dependable and precise but also environmentally friendly.
While numerous sensors have been developed for measuring temperature and humidity across diverse growing environments, a key challenge is to ensure that these devices remain effective, eco-friendly, and economically viable.
“In recent years, agriculture has been significantly impacted by extreme changes in environmental factors like humidity and temperature, highlighting the urgent need for innovative solutions to boost productivity and enhance quality while minimizing environmental footprints,” explained author Masoud Mahjouri-Samani.
Flexible electronic devices and sensors can be produced quickly and efficiently. Various printing technologies, such as aerosol-jet printing, inkjet printing, gravure printing, and screen printing, are employed in fabricating these sensors. However, due to the liquid nature of these printing methods, which are incompatible with biodegradable materials, most production is done on non-biodegradable plastics.
Paper serves as a superior alternative compared to traditional plastic materials, as its cellulose fibers provide a porous surface while being biodegradable and readily available.
The research team developed the temperature and humidity sensors by printing silver lines onto four types of commercially available paper through dry additive nanomanufacturing. The printed electrodes are monitored for changes in capacitance and resistivity to assess variations in temperature and humidity. Capacitance changes are measured as the paper absorbs water vapor, indicating the environmental humidity levels.
The temperature-sensing function relies on resistance changes, whereby an increase in temperature results in heightened resistivity of the metallic conductor.
These sensors have demonstrated reliability and sensitivity to temperature and humidity variations. They effectively track humidity shifts between 20% and 90%, as well as temperature changes ranging from 25°C to 50°C. Additionally, these biodegradable sensors are cost-effective, reusable, and can be safely disposed of when necessary.
“By merging advanced techniques like dry additive nanomanufacturing with biodegradable materials, this research balances functionality with environmental stewardship, addressing the increasing challenges associated with electronic waste disposal,” noted Mahjouri-Samani. “This method has the potential to transform smart agricultural practices through enhanced monitoring of critical factors influencing plant growth.”
