Farmers can already use drones to soar over huge fields and monitor temperature, humidity or crop health. But these machines need so much power to fly that they can't get very far without needing a charge. Now, engineers have created a sensing system that is small enough to ride aboard a bumblebee.
Engineers at the University of Washington have created a sensing system that is small enough to ride aboard a bumblebee. Because insects can fly on their own, the package requires only a tiny rechargeable battery that could last for seven hours of flight and then charge while the bees are in their hive at night.
Drones of comparable size normally fly for 10 or 20 minutes before they need to charge again, whereas these bees can collect data for hours. The team showed for the first time that it's possible to actually do all this computation and sensing using insects in lieu of drones.
While using insects instead of drones solves the power problem, this technique has its own set of complications: First, insects can't carry much weight. And second, GPS receivers, which work well for helping drones report their positions, consume too much power for this application. To develop a sensor package that could fit on an insect and sense its location, the team had to address both issues.
Previously other research groups have fitted bumblebees with simple "backpacks" by super-gluing small trackers, like radio-frequency identification, or RFID, tags, to them to follow their movement. For these types of experiments, researchers put a bee in the freezer for a few minutes to slow it down before they glue on the backpack. When they're finished with the experiment, the team removes the backpack through a similar process.
These prior studies, however, only involved backpacks that simply tracked bees' locations over short distances -- around 10 inches, and did not carry anything to survey the environment around the insects. Here, the group designed a sensor backpack that rides on the bees' backs and weighs 102 milligrams, or about the weight of seven grains of uncooked rice.
Because bees don't advertise where they are flying and because GPS receivers are too power-hungry to ride on a tiny insect, the team came up with a method that uses no power to localize the bees. The researchers set up multiple antennas that broadcast signals from a base station across a specific area. A receiver in a bee's backpack uses the strength of the signal and the angle difference between the bee and the base station to triangulate the insect's position.
Next the team added a series of small sensors, monitoring temperature, humidity and light intensity, to the backpack. That way, the bees could collect data and log that information along with their location, and eventually compile information about a whole farm.
Then after the bees have finished their day of foraging, they return to their hive where the backpack can upload any data it collected via a method called back-scatter, through which a device can share information by reflecting radio waves transmitted from a nearby antenna.
Right now the backpacks can only store about 30 kilobytes of data, so they are limited to carrying sensors that create small amounts of data. Also, the backpacks can upload data only when the bees return to the hive. The team would eventually like to develop backpacks with cameras that can live-stream information about plant health back to farmers.