Author(s): Victor Buratto Tinti, Jin Kyu Han, Valdemar Frederiksen, Huaiyu Chen, Jesper Wallentin, Innokenty Kantor, Anton Lyksborg-Andersen, Thomas Willum Hansen, Garam Bae, Wooseok Song, Eugen Stamate, Daniel Zanetti de Florio, Henrik Bruus, and Vincenzo Esposito

DOI: 10.1126/sciadv.adq344

Abstract: Electromechanical metal oxides, such as piezoceramics, are often incompatible with soft polymers due to their crystallinity requirements, leading to high processing temperatures. This study explores the potential of ceria-based thin films as electromechanical actuators for flexible electronics. Oxygen-deficient fluorites, like cerium oxide, are centrosymmetric nonpiezoelectric crystalline metal oxides that demonstrate giant electrostriction. These films, deposited at low temperatures, integrate seamlessly with various soft substrates like polyimide and PET. Ceria thin films exhibit remarkable electrostriction (M33 > 10−16 m2 V−2) and inverse pseudo-piezo coefficients (e33 > 500 pmV−1), enabling large displacements in soft electromechanical systems. Our study explores resonant and off-resonant configurations in the low-frequency regime (<1 kHz), demonstrating versatility for three-dimensional and transparent electronics. This work advances the understanding of oxygen-defective metal oxide electromechanical properties and paves the way for developing versatile and efficient electromechanical systems for applications in biomedical devices, optical devices, and beyond.

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