Natural hearing which means hearing naturally like normal people is critical for patients with hearing loss to participate in life. Cochlear implants have enabled numerous severe hearing loss patients to hear voice functionally, while cochlear implant users can hardly distinguish different tones or appreciate music subject to the absence of rate coding and insufficient frequency channels. Here a bioinspired soft elastic metamaterial that reproduces the shape and key functions of the human cochlea is reported. Inspired by human cochlea, the metamaterials are designed to possess graded microstructures with high effective refractive index distributed on a spiral shape to implement position-related frequency demultiplexing, passive sound enhancements of 10 times, and high-speed parallel processing of 168-channel sound/piezoelectric signals. Besides, it is demonstrated that natural hearing artificial cochlea has fine frequency resolution up to 30 Hz, a wide audible range from 150-12 000 Hz, and a considerable output voltage that can activate the auditory pathway in mice. This work blazes a promising trail for reconstruction of natural hearing in patients with severe hearing loss.
Keywords: cochlear implants; elastic metamaterials; natural hearing; piezoelectric materials; soft materials.
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