Self-powered sound detection and recognition sensors based on flexible polyvinylidene fluoride-trifluoroethylene films enhanced by in-situ polarization

A flexible, accurate and highly sensitive sound detection and recognition sensor was fabricated in this study; this was achieved by employing a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) film and in-situ polarization. The PVDF-TrFE film was polarized using our polarization system within 5 min without heating; further, this system has the advantages of high production efficiency, excellent piezoelectric performances, and good uniformity compared to traditional poling approaches. The sound detection and recognition sensor responded to various types of sound waves in a wide range of frequencies with an error of less than 1% by producing corresponding voltage signal; these can be used to accurately identify complex sound signals with different frequencies and different intensities. Furthermore, the sensor was flexible and self-powered. All the above features render it hold great potential in various applications, such as microphones, biometrics, environmental protection and artificial intelligence.