The 98-milligram system, say the researchers, is the first such system that can airdrop wireless sensors from small drones and live insects, enabling sensors to be deployed in areas that are otherwise hard to reach. The system can ride aboard a small drone or an insect - such as a moth - until it gets to its destination, at which point the sensor is released from its perch via a Bluetooth command.
Due to its tiny mass and size, say the researchers, the system can fall up to 72 feet - from about the sixth floor of a building - and land without breaking. Once on the ground, the sensor can collect data, such as temperature or humidity, for almost three years.
“We have seen examples of how the military drops food and essential supplies from helicopters in disaster zones," says Shyam Gollakota, a UW associate professor in the Paul G. Allen School of Computer Science & Engineering and senior author of a paper on the research. "We were inspired by this and asked the question: Can we use a similar method to map out conditions in regions that are too small or too dangerous for a person to go to? This is the first time anyone has shown that sensors can be released from tiny drones or insects such as moths, which can traverse through narrow spaces better than any drone and sustain much longer flights."
The sensor is held on the drone or insect using a magnetic pin surrounded by a thin coil of wire. To release the sensor, a researcher on the ground sends a wireless command that creates a current through the coil to generate a magnetic field. The magnetic field makes the magnetic pin pop out of place and sends the sensor on its way.
The sensor, say the researchers, was designed with its battery, the heaviest part, in one corner. As the sensor falls,