There is no shortage of places on Earth that are difficult for researchers to study, either because they’re dangerous or inaccessible. 

Now, researchers at the University of Washington (UW) say they’ve come up with a potential solution: a tiny 98-milligram sensor system—less than one-hundredth of an ounce—that can be carried by an insect or ride aboard a tiny drone until it gets to its destination.

The sensor

The sensor pictured here can fit atop the surface of a penny. Image used courtesy of Iyer et al./MobiCom 2020 and the University of Washington
 

Once there, on receipt of a Bluetooth command, the sensor is released from its perch and can fall from up to 72 feet and land without breaking.

Making the Inaccessible Accessible

Presenting their research at MobiCom 2020, the UW team explain how the work was inspired by how the military drops food and essential supplies from helicopters in disaster zones

“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?” said senior author Shyam Gollakota, a UW associate professor.

The sensor is so small that it can be carried by an insect

The sensor is so small that it can be carried by an insect—for example, a moth. Image used courtesy of Mark Stone, University of Washington
 

According to the researchers, this is the first time that anyone has demonstrated that sensors can be released from tiny drones or insects such as moths, which are able to traverse narrow spaces and dangerous environments better than any drone. They can also fly farther and for longer because there are no constraints such as battery power. 

A Unique Mechanical Release Mechanism

To secure the sensor to a drone or insect, a magnetic pin surrounded by a thin coil of wire is used. It can then be released when a researcher on the ground sends a wireless command that creates a current through the coil to generate a magnetic field. This magnetic field causes the magnetic pin to pop out of place, allowing the sensor to drop to the ground, fluttering as it falls from heights of up to 22 meters. 

The sensor can also be dropped by a small drone

In addition to insect transport, the sensor can also be dropped by a small drone. Image used courtesy of Mark Stone, University of Washington
 

The researchers say that their system is the first of its kind, enabling airdropping of wireless sensors that are low-power, long-range, and don’t sustain any damage due to their tiny mass and size. 

Construction of the Sensor

As for the sensor, it was designed with its battery in one corner. As the sensor falls, this battery begins rotating around the corner to generate additional drag force and slow its descent. This, combined with the sensor’s low weight, limits maximum fall speed at around 11 miles per hour. 

Next up on the research team’s agenda is developing a mechanism to recover the sensors once their batteries have died. Once this has been achieved, the team believes that their system could be used in a variety of locations, including environmentally-sensitive areas with certain landscapes, wildlife, or historical value.

Source: All About Circuits