Named Luciola for its resemblance to the firefly, the featherweight levitating particle weighs 16.2 mg, has a diameter of 3.5 mm (0.14 inch), and emits a red glimmer that can just about illuminate text.
But its minuscule size belies the power of the 285 microspeakers emitting ultrasonic waves that hold up the light, and have a frequency inaudible to the human ear, allowing Luciola to operate in apparent total silence.
It took two years for Luciola to get this far, said circuit design specialist Makoto Takamiya, a member of the Kawahara Universal Information Network Project that developed the device.