We have seen Harvard's Robobee flying robot developed for years: After learning to fly, it learned to swim in 2015 and then jump out of the water again in 2017 – and now it has another trick that it doesn't exist sleeve. The Robobee X-Wing can fly using only the force it collects from light hitting its solar cells, allowing it to stay in the air indefinitely.
Getting flight on this scale is extremely difficult. You may think it is small, it would be easy to go and maintain the flight as an insect does. But self-propelled flights get much harder the less, which puts insects among the most enchanting amazing techniques we've found in nature.
Oh, it's easy enough to fly when you have a wire feeding you electricity for power a few small wings ̵
The new Robobee X-Wing (named after its 4-wing architecture) achieves a new milestone with the ability to fly without a battery and no laser – only ordinary spectrum light comes from above. Lighter than sunlight, to be fair – but close to real conditions.
The team at Harvard's Microrobotics Laboratory has achieved this by making power conversion and wing mechanical systems incredibly lightweight – all weighing about. quarter in grams, or approx. a half paper clip. Its power consumption is also lilliputian:
Consuming only 110-120 milliwatts of power, the system matches the pressure efficiency of similar sized insects such as bees. This insect scale aircraft vehicle is the easiest hitherto to achieve sustained, unbound flight (as opposed to impulsive jump or lift).
This last bit is a little shadow cast by its competitors, which by nature cannot quite achieve "sustained untethered flight," even though what constitutes it is not quite clear. This Dutch pet leaf can after all go a mile on battery power. If it's not persistent, I don't know what it is.
In the Robobee video, you can see that when activated, it records as a bottle rocket. One thing they don't really have room for on the robot's small body (yet) is sophisticated airplane control electronics and power supplies that allow it to use only the energy it needs, flaps in place.
This is probably the next step for the team and it is a non-trivial one: adding weight and new systems alters the whole airplane profile. But give them a few months or a year, and this thing will float like a real dragonfly.
Robobee X-Wing is exhaustively described in a paper published in the journal Nature.