Realization of active noise control using a flexible graphene-film acoustic actuator

Present study developed a novel graphene-film acoustic actuator (GFAA) by its flexible, non-mechanical vibration structure, which offers a flat amplitude-frequency response and high output sensitivity. We improved the manufacturing processes by using photographic paper substrate, surface-microfabricated interdigitated electrodes and micro-electronic inkjet printing, letting our flexible GFAA achieve almost an 1.8 times output increment. Subsequently, the acoustic performance, frequency response, and compatibility of the GFAA with an active noise control (ANC) system were evaluated. In this system, the GFAA functions as a secondary sound source to control the primary noise source through a forward-feedback algorithm implementing in the filedprogrammable gate array. At first stage, discrete tonal signals, multiple tonal signals and broadband noises were effectively reduced by the GFAA-ANC system, and a maximum of 14 dB was achieved. At second stage, to demonstrate the unique flexibility of the GFAA, it was attached to the curved surface of a NACA0012 airfoil, where it directly controlled the random pressure fluctuations generated by quasi-turbulence, achieving a noise reduction of approximately 8 dB and surpassing traditional control methods. Finally, error analysis was conducted to confirm the application range of GFAA, whereas the hardware computation speed rather than GFAA mainly limited the control efficiency of noise signals above 2000 Hz.