Flexible Piezoelectric\nNanocolumnar Composite Films\nas Flat-Panel Loudspeakers: Application and Modeling

Highly anisotropic piezoelectric composites promise to\nprogress\nelectroacoustic devices as a class by combining the advantages of\nboth piezoceramics and polymers. Fundamentally, piezoelectric loudspeakers\nemploy the converse piezoelectric effect to convert electrical to\nmechanical energy. Quasi-1–3 piezoceramic/polymer composites\nenable flat-panel loudspeakers that are tunable in elastic modulus,\nwith opportunities for mechanical flexibility, optical transparency,\nand large-area coverage. Their processing route enables relatively\nflexible design parameters, such as the particle loading, polymer–matrix\nmodulus, film thickness, film size, and electrode-material stiffness.\nAlternative processing routes of electric field (E-field) aligned-piezoelectric\ncomposites are demonstrated, including using the relaxor ferroelectric\nlead magnesium niobate–lead titanate (PMN–PT) to enhance\nthe acoustic performance and photocurable resins to accelerate the\nmaterials processing. Material properties critical for dielectrophoresis\nare characterized, and loudspeakers were fabricated based on the optimal\nprocessing conditions. Subsequently, electroacoustic characterization\nexplores the effect of loudspeaker size, substrate stiffness, the\nmicrophone distance, the piezoceramic material, and the matrix modulus.\nFinally, finite-element (FE) modeling of the electromechanical behavior\nvalidates the natural frequencies and modes shapes of the loudspeakers\nvia the analytical solution and frequency response to electrical and\nmechanical excitation. Good correspondence between the predicted electroacoustic\nperformance and experimentally validated model is observed.