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This paper presents a review of the radio frequency thin-film lithium niobate (LiNbO3) based acoustic microsystems. Thanks to their high electromechanical coupling (k 2), low loss, and great frequency scalability, thin-film LiNbO3 has outperformed state-of-the-art acoustic technologies in the past decade. This paper first reviews the acoustic wave transduction and propagation in thin-film LiNbO3 and then showcases the emerging acoustic applications. Outlook for further platform development and more functions is offered for future thin-film LiNbO3 based acoustic microsystems development. [ABSTRACT FROM AUTHOR]

This paper presents a non-resonant, gravity-induced micro triboelectric harvester with high internal resistance. The device collects kinetic energy from low-frequency jiggling movements for the power supply of portable electric devices such as wristwatches. It includes a friction module to produce triboelectric charge and an electrostatic induction module to export energy. The friction that transfers charge is induced by jiggling movements, with gravity and inertia of an internal slider, instead of with external direct force. The non-resonant structure allows the device to respond to low frequencies of 1.5–5.5 Hz, covering the frequencies of human motion. Load resistance sweeping shows that the optimal load resistance is about 1.1 GΩ, with the peak output voltage of about 260 V, and the output power of 60 µW. The proposed harvester responds to low-frequency kinetic energy in jiggling movements matching that of a human limb's running motion; so it has potential to convert the mechanical energy of arm swings or strides into electric energy. [ABSTRACT FROM AUTHOR]