A novel tiny triboelectric acoustic sensor design based on nanocomposite enhancement for highly-sensitive, broadband, and self-powered multi-functional applications

This work proposes a novel acoustic nanocomposite fibrous membrane-based triboelectric nanogenerator (NFM-TENG) with excellent acoustical-to-electrical conversion performance. The optimal combination for the triboelectric pairs of NFM-TENG is identified: a polyvinylidene fluoride-multiwalled carbon nanotubes (PVDF-MWCNTs ( 1 wt$\text{\%}$)) nanofibrous membrane as the tribo-positive layer, and a corona-charged fluorinated ethylene-propylene (FEP) solid membrane as the tribo-negative layer, resulting in higher electric output than single-friction-layered NFM-TENG (32 times). Under the acoustic excitation of 116 dB at 200 Hz, the acoustic NFM-TENG can generate a maximum areal power density of 3.78 W/ m${}^2$. The NFM-TENG can be used not only as a acoustic energy harvester, but also as a self-powered triboelectric acoustic sensor (TAS) for real-time voice recording and control. For convenience, for the first time, an advanced tiny TAS (TTAS, diameter: only 9.7 mm) based on the NFM-TENG is developed and its sensitivity is calibrated as -50 dB according to the International standard IEC61094. Experimental results also verified that the TTAS with broadband response ability (20–20,000 Hz) is fully competent for commercial applications such as real-time voice control, HMI, and other multi-scenarios. The TTAS is smart, reliable and customizable, potentially leading to a new revolution in intelligent interaction.