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This insect-sized drone can fly without any moving parts. How? Physics

The Ionocraft - March 2018

Flying drones can vary in size anywhere from cute little quadcopters that fit in the palm of your hand to giant passenger drones capable of transporting multiple people and their luggage. One thing that almost all of these have in common: the need for moving parts to get them airborne. That’s something a new drone called the ionocraft doesn’t feel the need to adhere to.

Developed by researchers from the University of California, Berkeley, it’s not only described as the smallest flying robot ever made, but one which flies with zero moving parts: meaning no rotors, wings, or similar appendages. Instead, the insect-scale robot relies on atmospheric ion thrusters which allow it to move completely silently.

“To understand how it works, imagine two asymmetric — [such as] a wire and a plate — electrodes,” Daniel Drew, currently a Postdoctoral Fellow in the Mechanical Engineering department at Stanford University, told Digital Trends. “When a voltage is applied between the two, the electric field will be stronger in the vicinity of the wire as a function of its geometry. If this field is strong enough, an ambient electron can be pulled in with enough kinetic energy to initiate avalanche breakdown through impact ionization. There’s now a stable plasma, glowing purple in the dark, around the top wire. Generated ions will be ejected from this plasma, drifting in the electric field towards the bottom electrode. Along the way, they collide with neutral air molecules and impart momentum, producing a net thrust.”

Putting your hand below the ionocraft’s bottom electrode produces the same feeling of accelerated air flow as you would find if placing your hand under a spinning propeller. This mechanism is known as “electrohydrodynamic force,” while the ion generation is achieved using “corona discharge.”

Drew suggests that the mechanical simplicity of the propulsion system should make these drones easy to manufacture. And their lack of moving parts or sound could make them useful for tasks such as surveillance and indoor sensing.

“The immediate next step is for controlled flight using onboard sensing and an external controller, with wires for data transfer and power,” he continued. “We believe that we are very close to achieving this goal. The path toward autonomous flight will require low mass power electronics currently being developed by a collaborator, a single chip solution to computation and wireless communication currently being tested in our lab, and high-energy-density thin-film batteries such as those produced in the labs of fellow Berkeley researchers.”

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