- The RFID-based sensors work in both indoor and outdoor lighting conditions, and can communicate at greater distances
- They could be used for monitoring temperature, soil and energy use, as well as cargo tracking
- The researchers also plan to add the ability to measure humidity, pressure, vibration and pollution
It is being estimated that by 2025, the number of internet of things (IoT) devices could rise to 75 billion worldwide. This means there could be billions of sensors all around us. However, as sensors require batteries that must be replaced frequently, they can be problematic for long-term monitoring.
To solve this problem, researchers at Massachusetts Institute of Technology (MIT) have designed photovoltaic-powered sensors that can transmit data for years before needing replacement.
To do so, they mounted thin-film perovskite cells— known for their potential low cost, flexibility, and relative ease of fabrication — as energy-harvesters on inexpensive radio-frequency identification (RFID) tags.
The team found that the cells could power the sensors in both bright sunlight and dimmer indoor conditions. Moreover, solar power gave the sensors a major power boost, enabling greater data-transmission distances and the ability to integrate multiple sensors onto a single RFID tag.
MIT Auto-ID Laboratory and MIT Photovoltaics Research Laboratory researchers used the sensors to continuously monitor indoor and outdoor temperatures over several days. They observed that the sensors transmitted data continuously at distances five times greater than traditional RFID tags — with no batteries required.
The researchers say that such light-powered sensors can be valuable for any application requiring long-term sensing, indoors and outdoors, including tracking cargo in supply chains, monitoring soil, and monitoring the energy used by equipment in buildings and homes.
The RFID circuit was prototyped to only monitor temperature. Next, the researchers aim to scale up and add more environmental-monitoring sensors to the mix, such as humidity, pressure, vibration and pollution. Deployed at scale, the sensors could especially aid in long-term data-collection indoors to help build, say, algorithms that help make smart buildings more energy efficient.
“The perovskite materials we use have incredible potential as effective indoor-light harvesters. Our next step is to integrate these same technologies using printed electronics methods, potentially enabling extremely low-cost manufacturing of wireless sensors,” says Department of Mechanical Engineering (MechE) postdoc Ian Mathews.
The research was published in Advanced Functional Materials and IEEE Sensors.