2018.01.09

In this paper, the researchers present an approach to realize the levitation of a small object with an embedded electronic circuit.

Luciola is a light-emitting particle with a diameter of 3.5mm and a weight of 16.2mg moving in mid-air in a 10.4cm x 10.4cm x 5.4cm space through acoustic levitation using two 40-kHz 17 x 17 ultrasonic transducer arrays placed face-to-face at a distance of 20cm and wirelessly powered by 12.3-MHz resonant inductive coupling. The novelty of this paper is the acoustically levitated electronic object by the combined application of ultrasonic levitation and wireless powering to the levitated electronic object.

A new shape of the levitated object and a new placement of the receiver coil to simultaneously realize acoustic levitation and wireless powering are proposed, achieving a stable wireless powering to a rotating levitated object at the bottom of an acoustic potential. To enable the levitation of a particle, a custom IC chip is essential in reducing the size and weight of the particle.

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. Luciola is applied to a self-luminous pixel in a mid-air display and drawings of characters in mid-air are demonstrated.

Associate Professor Makoto Takamiya, VLSI Design and Education Center (VDEC) and Department of Electrical Engineering and Information Systems, Associate Professor Yoshihiro Kawahara, Graduate School of Information Science and Technology, and other researchers.

Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies (IMWUT)：https://dl.acm.org/citation.cfm?id=3161182