Mechanically guided 4D printing of a triboelectricity-driven acoustic transducer for self-powered and intelligent voice recognition

Triboelectricity-driven acoustic transducers with various merits have demonstrated significant potential in energy harvesting and self-powered sensing. The transducers generally require additionally a spacer and a corresponding exquisite process for smooth operation, which provides an unnecessary interface between the elements. The exploration of a novel manufacturing approach for triboelectricity-driven acoustic transducers is warranted to resolve this issue. Here, Triboelectricity-driven Oscillating Nano-Electricity generator (TONE) developed via mechanically guided four-dimensional (4D) printing is introduced for acoustic energy harvesting and self-powered voice recognition. The mechanically buckled structure of the TONE facilitates its smooth oscillation by sound wave without the use of an additional spacer, enabling the TONE to exhibit outputs of 156 V and 10 μA. The output characteristics of the TONE are analyzed based on the acoustic-structural-triboelectric interaction mechanism. The TONE demonstrates practical versatility by providing power to commercial electronics from controlled/daily sound and being utilized in artificial intelligence-based human voice recognition sensors.