In this work, the electret properties of poly(vinylidene fluoride) (PVDF)/lithium niobate (LiNbO3, LN) nanocomposites are systematically studied. The LN nanoparticles are fabricated by hydrothermal synthesis followed by melt‐reaction. Their morphology and crystalline structures are characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The PVDF/LN nanocomposite films are prepared by solution casting with N,N‐dimethylformamide (DMF) as the solvent or melt molding. The crystalline phases of PVDF in both pure samples and nanocomposites are checked by XRD and Fourier transform infrared spectroscopy (FTIR). The measurements of the dielectric and electret properties show that the LN nanoparticles significantly increase the dielectric permittivity (ε) and the thermally stimulated discharge current (TSDC) of the samples. Such materials have potential applications including for air filters and power generators. A demonstration shows that after the same charging process, the PVDF/LN nanocomposites can absorb larger amount of polystyrene (PS) foam microparticles or micrometer size test dusts than the pure PVDF.

This study has proposed a novel music player controlling method based on gesture recognition, which translating the gesture interacting signal into a controlling instruction for the music player. Firstly, utilizing the laptop's webcam to capture the image information, and then employing the image processing method to tackle it. The skin color detection was used to obtain the information of gesture candidates, and a background subtraction was introduced to eliminate the distributing information. Moreover, in order to ensure the rapid and effective implementation of music player proposed here, the barycenter of a gesture was calculated as one Recognized Reference Information (RRI); a ratio between the gesture's width and height was also selected as the other RRI; the comparison of these two RRI values was utilized to obtain a pattern signal of the gesture which was corresponding to the controlling instruction for the Music Player. Eventually, a Music Player was programmed and the pattern signal generated by gesture recognition was used to control the Music Player as willing to realize four basic functions: "play", "pause", "previous" and "next". A series of tests using our gesture recognition based Music Player was conducted under the condition with different kinds of complex backgrounds, and the results showed the satisfactory performance of our interactive designing.

To overcome the fiber-spinning problem of poly(vinylidene fluoride) (PVDF) because of its high melt viscosity and rapid crystallization, polyamide 11 (PA11) with excellent melt spinning capability and good electret properties is incorporated to prepare blends by melt mixing. Their crystal structure, morphology, electrical polarization properties, and melt spinning performance are systematically characterized by various techniques. It is found that the incorporation of PA11 reduces the crystallinity of PVDF, increases its thermally stimulated discharge current, and reduces its viscosity. Therefore, the blends show much better melt spinning capability. For such blends, the addition of outstanding inorganic electret materials, lithium niobate (LiNbO 3 , LN) nanoparticles is found to further improve the materials' electret properties. Such a strategy is proved to be successful in melt spinning PVDF electrets into fine fibers, which is beneficial to their applications in air filtration and other related fields.