Piezoelectric cantilever beams are commonly utilized to harvest energy from environmental vibrations due to their simple structures. This paper optimizes a single crystal trapezoidal hollow structure piezoelectric cantilever beam vibration energy harvester with a copper substrate to achieve high energy density at a low frequency. Finite element analysis (FEA) is adopted to optimize the size of the copper substrate at first, and the piezoelectric energy harvester (PEH) is further optimized with a trapezoidal hollow structure under the optimal size of the copper substrate. The developed PEH with a trapezoidal hollow structure (L_a = 20 mm, L_b = 15 mm, and L_h = 40 mm), with a copper substrate of 80 mm × 33 mm × 0.2 mm, can obtain the best output performance. Under the condition of 1 g acceleration, the resonance frequency and peak voltage output were 23.29 Hz and 40.4 V, respectively. Compared with the unhollowed PEH, the developed trapezoidal hollow structure PEH can reduce its resonant frequency by 12.18% and increase output voltage by 34.67%, while also supplying a power density of 7.24 mW/cm³. This study verified the feasibility of the optimized design through simulation and experimental comparison.

As the development of wireless communication devices tends to be highly integrated, the miniaturization of very low frequency (VLF) antenna units has always been an unresolved issue. Here, a novel VLF mechanical communication antenna using magnetoelectric (ME) laminates with bending-mode structure is realized. ME laminates combines magnetostrictive Metglas amorphous ribbons and piezoelectric 0.7Pb(Mg_1/3Nb_2/3)O₃–0.3PbTiO₃ single crystal plates. From the simulation, we confirmed that the ME laminates can reduce the resonance peak from 18 kHz to 7.5 kHz by bending-mode structure. Experiment results show the resonance frequency can be farther reduced to 6.3 kHz by clamping one end of the ME antenna. The ME laminate exhibits a giant converse ME coefficient of 6 Oe cm V⁻¹ at 6.3 kHz. The magnetic flux density generated by the ME antenna has been tested along with distance ranging from 0 to 60 cm and it is estimated that a 1 fT flux could be detected around 100 m with an excitation power of 10 mW.

Driven largely by the recent growth in the Internet of Things, there is a rapid surge in the demand for low-powered or self-powered sensors and devices. Here, we report a fully self-powered magnetic sensor system based on the magnetoelectric (ME) effect. This device consists of both a field-detection element and a power-generation element, which are designed using magnetostrictive Metglas amorphous ribbons and piezoelectric PMN-PT single crystal plates, respectively. The ME laminates for energy harvesting exhibit a giant resonance magnetic responsivity of 350 nC/Oe at 15 kHz. The magnetic-field sensing element shows a linear response with a high resolution up to 32 nT, and the magnetic-harvest element can reach a power of 48.68 mW/Oe at an optimum load resistance of 5 kΩ. The self-powered sensor system has shown excellent capability to convert magnetic energy into electrical energy, as demonstrated in powering a small electronic screen. The high sensitivity and power generation of our system suggest potential applications in sustainable intelligent sensor networks.

High conductive environments such as deep earth and seawater bring challenges to existing electronic communication technology. Very Low Frequency (VLF) communication technology is supposed to be a feasible solution for conductive environments communication due to its improved radiation attenuation. Herein, we report a VLF 2 Frequency Shift Keying (2FSK) signal receiving antenna based on Metglas/0.7Pb(Mg _1/3 Nb _2/3 )O ₃ –0.3PbTiO ₃ (PMN-PT) magnetoelectric (ME) cantilever. The cantilever beam is predicted by finite element simulation and shows double electromechanical resonance (EMR) peaks. Experimental results reveal that the ME cantilever demonstrate strong resonant ME coupling coefficients as high as α _Q ⁓ 100 nC/Oe at 6 kHz and 18 kHz, which ensures the high responsivity and low bit error rate during modulation in FSK communication application. The noise equivalent magnetic field of the whole antenna system at the resonant peak is measured to be as low as 12.56 fT/Hz ^1/2 (at 18.44 kHz), implying a huge signal to noise ratio (SNR) advantage. On the basis of the above preparation, the ability of ME antenna to receive 2FSK signal is verified. ME antenna shows good performance on demonstrate FSK signals reception which is 200 bit/s. Such an ME composite based mechanical antenna shows great potential in the conductive environmental communication application.

Road map for patterned growth of two-dimensional atomic-layer semiconductors.

In this work, a tachometer based on a Metglas/PZT/Metglas magnetoelectric (ME) composite was developed to achieve high-precision rotational speed measurement over a wide temperature range (−70 °C to 160 °C). The tachometer converts external magnetic signals into electrical signals through the ME effect and operates stably in extreme temperature environments. COMSOL Multiphysics software was used for simulation analysis to investigate the ME response characteristics of the composite in such environments. To evaluate the properties of the ME composite under different conditions, its response characteristics at various frequencies, DC bias, and temperatures were systematically investigated. A permanent magnet and a DC motor were used to simulate gear rotation, and the voltage output was analyzed by adjusting the position between the sensor and the DC motor. The results show that the measured values of the ME tachometer closely match the set values, and the tachometer demonstrates high measurement accuracy within the range of 480 to 1260 revolutions per minute (rpm). Additionally, the properties of the ME composite at different temperatures were examined. In the temperature range from −70 °C to 160 °C, the ME coefficients exhibit good regularity and stability, with the measured trend closely matching the simulation results, ensuring the reliability and accuracy of the ME tachometer. To verify its practicality, the measurement capability of the ME tachometer was comprehensively tested under extreme temperature conditions. The results show that in high-temperature environments, the tachometer can accurately measure speed while maintaining a high signal-to-noise ratio (SNR), demonstrating excellent anti-interference ability. The proposed ME tachometer shows promising application potential in extreme temperature conditions, particularly in complex industrial environments that require high reliability and precision.