Artificial Cilia for 360° Direction-Sensitive Acoustic Sensing Through Additive Micromanufacturing

Directional acoustic sensing can be used for localization and detection, has a wide range of applications in various fields, including rescue robotics, drone positioning, and underwater navigation. It is, however, a challenge to sense both the amplitude and direction of the acoustic waves with a simple sensor design. In this paper, a series of artificial cilia is prepared using additive micro-manufacturing technologies for direction-sensitive acoustic sensing, including electrospray and 3D micro-direct ink writing. The response of the artificial cilia at resonance is significantly enhanced, while the resonance frequencies decrease with increasing length, and the response increases due to the amplification. Two resonances are achieved on a cilium by printing two independent electrode-to-electrode interconnect bridges. Two signal channels of the artificial cilia produce an ‘8’-shaped loop by varying acoustic excitation angles, showing that both amplitude ratio and phase difference are direction-dependent. The two voltages of the artificial cilia can be decoupled to produce different frequencies, amplitudes, and phase differences, thus enabling directional detection of multiple sound sources. The direction-sensitive acoustic sensing is achieved by micro-manufacturing artificial cilia. This effort opens an avenue in the fields of cochlear and device detection with promising applications.