Fully Transparent Flexible Piezoelectric Sensing Materials Based on Electrospun PVDF and Their Device Applications

Advanced transducer materials have become increasingly important with the rapid development of the internet of things and flexible electronics. Herein, fully transparent flexible polyvinylidene fluoride/polydimethylsiloxane (PVDF/PDMS) composite piezoelectric films are fabricated using scrape coating techniques based on electrospun PVDF nanofiber films. Compared to the electrospun PVDF, the PVDF/PDMS not only owns high transparency and a more uniform and stable structure but also has superior piezoelectric properties. Based on the electrospun PVDF and the PVDF/PDMS films, flexible piezoelectric sensors are developed, which can effectively detect weak mechanical signals including finger tapping and bending signals, radial artery pulses, and environmental sound signals. The PVDF/PDMS sensor performs better than the electrospun PVDF sensor and presents great potential for applications in flexible sensors and transducers. Especially, thanks to their high transparency, the PVDF/PDMS composite piezoelectric films lend themselves easily to application fields requiring transparent sensors such as imperceptible sensors and human-machine interfaces, display devices, electronic skins, intelligent windows, etc. Polyvinylidene fluoride (PVDF) nanofiber films containing a high beta-phase content of approximate to 75% are prepared via electrospinning. Highly transparent piezoelectric PVDF/polydimethylsiloxane (PDMS) composite films with a transmittance of approximate to 88.5% over the visible light range are obtained by filling the PVDF microfiber films with PDMS. The flexible PVDF/PDMS film exhibits a d33 of 8 pC/N and can detect body signals and environmental weak mechanical excitation.image