Pattern Reconfigurable Ultrasonic Sound Source Using Laser-Induced Graphene Interdigitated Electrodes

We realized a pattern reconfigurable ultrasonic sound source using laser-induced graphene (LIG). In the proposed device, interdigitated electrodes composed of LIG are patterned on a polyimide film. By placing a conductive material on the device's backside, the current is transmitted only in the contact area using the capacitance coupling between the film and the conductive material. While conventional thermoacoustic sound sources cannot change an active LIG area without remaking, the proposed device can reconfigure the active area only by changing the pattern of the conductive material. We confirmed turning on the sound pressure emission from the fabricated device when placing an aluminum block as the conductive material. The sound pressure emitted by the device is maximized at 50 kHz. The results indicate that the device is helpful for pattern optimization for ultrasonic sound directivity.