The particle - named "Luciola" after the scientific name for a genus of "flashing" fireflies - is held and rotated in mid air by the combined application of ultrasonic levitation and wireless powering. Such a technique, say the researchers, could hold potential in applications such as moving displays and projection mapping.
The particle, which weighs 16.2 mg and has a diameter of 3.5 mm (0.14 inch), emits a red light that can be used to "draw" characters in mid air (see image, which shows long-time exposure). It moves within a 10.4 x 10.4 x 5.4-cm space and is levitated using two 40-kHz 17 x 17 ultrasonic transducer arrays placed face-to-face at a distance of 20 cm and wirelessly powered by 12.3-MHz resonant inductive coupling.
Luciola could find applications in the Internet of Things (IoT), in which everyday objects are connected to networks to send and receive data, say the developers. Equipped with movement or temperature sensors, Luciola could fly to such objects to deliver a message or help to make moving displays with multiple lights that can detect human presence, or participate in futuristic projection mapping events.
"Ultimately, my hope is that such tiny objects will have smartphone capabilities and be built to float about helping us in our everyday lives in smarter ways," circuit design specialist and University of Tokyo professor Makoto Takamiya told Reuters. The researcher hopes it will be commercially viable in five to ten years.
In the development of Luciola, a custom IC chip was required to reduce its size and weight to enable levitation. According to the researchers, in the design of the custom IC chip, "a new voltage detector circuit enabling an accurate voltage detection and a correct output during the start-up is proposed to achieve an intermittent lighting of the LED to increase the maximum distance between the transmitter and the receiver coil."
For more, see " Luciola: A Millimeter-Scale Light-Emitting Particle