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Nano- and micro-electromechanical systems (N/MEMSs) are traditionally based on electrostatic or piezoelectric coupling, which couples electrical and mechanical energy through acoustic resonator structures. Most recently, N/MEMS devices based on magnetoelectrics are gaining much attention. Unlike electrostatic or piezoelectric N/MEMS that rely on an AC electric field or voltage excitation, magnetoelecric N/MEMS rely on the electromechanical resonance of a magnetostrictive/piezoelectric bilayer heterostructure exhibiting a strong strain-mediated magnetoelectric coupling under the excitation of a magnetic field and/or electric field. As a consequence, magnetoelectric N/MEMS enable unprecedented new applications, ranging from magnetoelectric sensors, ultra-compact magnetoelectric antennas, etc. This Tutorial will first outline the fundamental principles of piezoelectric materials, resonator design, specifically different acoustic modes, and piezoelectric-based N/MEMS applications, i.e., radio frequency front end filters and infrared radiation sensors. We will then provide an overview of magnetoelectric materials and N/MEMS focusing on the governing physics of the magnetoelectric effect, magnetic material properties for achieving high magnetoelectric coupling, state-of-the-art magnetoelectric N/MEMS devices, and their respective applications. [ABSTRACT FROM AUTHOR]

Acoustically driven antennas operating at resonant wavelengths up to 105 times smaller than electrical antennas offer great potential for portable, low power communication systems in the very low frequency and low frequency range. Acoustic antennas with real resonant impedances have been demonstrated to offer orders of magnitude better total efficiency compared to similar sized, subwavelength electrically small antennas exhibiting large reactances. While most acoustic antennas share favorable impedance characteristics offering significant matching efficiency advantages over electrically small antennas, radiation efficiency varies greatly based on the implementation of the acoustically driven antenna. This paper presents a theoretical analysis of the three primary methods for implementing acoustically driven radiating elements, investigating both radiation and matching efficiencies comprising the total antenna efficiency. Radiation from the linear movement of unipolar charge driven both piezoelectrically and capacitively, the piezoelectrically actuated rotation of fixed dipole charges, and from flipping dipoles inside strain driven piezoelectrics are all presented and analyzed in terms of their design parameters and fundamental challenges. The efficiency of each type of acoustic antenna is referenced to an equivalent electrical antenna to benchmark the performance to a more familiar framework. Of the analyzed antenna types, piezoelectric alternating dipole antennas exhibit the most promise, with efficiencies more than a million times greater than electrically small antennas expected as piezoelectric materials, and resonator designs are optimized for acoustic radiation. [ABSTRACT FROM AUTHOR]