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A Lamb wave is a guided wave that propagates within plate-like structures, with its vibration mode resulting from the coupling of a longitudinal wave and a shear vertical wave, which can be applied in sensors, filters, and frequency control devices. The working principle of Lamb wave sensors relies on the excitation and propagation of this guided wave within piezoelectric material. Lamb wave sensors exhibit significant advantages in various sensing applications due to their unique wave characteristics and design flexibility. Compared to traditional surface acoustic wave (SAW) and bulk acoustic wave (BAW) sensors, Lamb wave sensors can not only achieve higher frequencies and quality factors in smaller dimensions but also exhibit superior integration and multifunctionality. In this paper, we briefly introduce Lamb wave sensors, summarizing methods for enhancing their sensitivity through optimizing electrode configurations and adjusting piezoelectric thin plate structures. Furthermore, this paper systematically explores the development of Lamb wave sensors in various sensing applications and provides new insights into their future development. [ABSTRACT FROM AUTHOR]

The intelligent sensing network is one of the key components in the construction of the Internet of Things, and the power supply technology of sensor communication nodes needs to be solved urgently. As a new field combining tribo-potential with semiconductor devices, tribotronics, based on the contact electrification (CE) effect, realizes direct interaction between the external environment and semiconductor devices by combining triboelectric nanogenerator (TENG) and field-effect transistor (FET), further expanding the application prospects of micro/nano energy. In this paper, the research progress of tribotronics is systematically reviewed. Firstly, the mechanism of the CE effect and the working principles of TENG are introduced. Secondly, the regulation theory of tribo-potential on carrier transportation in semiconductor devices and the research status of tribotronic transistors are summarized. Subsequently, the applications of tribotronics in logic circuits and memory devices, smart sensors, and artificial synapses in recent years are demonstrated. Finally, the challenges and development prospects of tribotronics in the future are projected. [ABSTRACT FROM AUTHOR]

Due to its potential harm to space payload, microwave corona breakdown of microstrip circuits has attracted much attention. This work describes an efficient way to suppress corona breakdown. Since the corona breakdown threshold is determined by the highest electric field intensity at the surface of microstrip circuits, lacquer coating with a thickness of tens of microns is sprayed on top of microstrip circuits. The applied dielectric coating is used to move the discharge location away from the circuit's surface, which is equivalent to reducing the highest electric field intensity on the interface of solid/air of the circuit and thus results in a higher breakdown threshold. Two designs of a classic coupled-line bandpass filter were used for verification. Corona experimental results at 2.5 GHz show that in the low-pressure range of interest (100 to 4500 Pa), a 5.3 dB improvement of the microwave corona breakdown threshold can be achieved for a filter with a narrowest gap of 0.2 mm, while its electrical performances like insertion loss and Q-factor are still acceptable. A threshold improvement prediction method is also presented and validated. [ABSTRACT FROM AUTHOR]

MgO and Al2O3 are two typical ceramics with high secondary electron yield (SEY) and are widely applied in electron multiplier devices as dynode coating. However, dynodes in multipliers are inevitably exposed to various environments, degenerating their SEY performance. To specify the influence of the atmospheric environment on SEY for MgO and Al2O3 ceramics, we conducted environmental stability experiments on MgO and Al2O3 nanofilms. By exposing the nanofilms fabricated by atomic layer deposition to air for certain durations, it was found that although the MgO film possessed high SEY, its SEY decreased significantly as the storage duration increased, specifically, its SEY peak value (δ m) decreased from 5.97 to 3.35 after 180 d. Whereas the SEY of the Al2O3 film changed very little with the storage duration extending, its δ m decreased from 4.01 to 3.70 after 180 d, indicating the Al2O3 film had good SEY environmental stability. To reveal the mechanism of SEY degradation, the modification analysis of surface composition was implemented. It was found that the surface of MgO film underwent degradation besides unavoidable contamination, generating Mg(OH)2 and MgCO3. Whereas, there is no chemical reaction occurred on the Al2O3 surface. Combining the advantages of high SEY of MgO and good environmental stability of Al2O3, several Al2O3/MgO double-layer nanofilms were prepared. The δ m value of 20 nm MgO nanofilms covered by 1 nm Al2O3, decreased from 4.90 to 4.56, with a reduction of only 6.94% after 180 d. The results showed that the Al2O3 film achieved effective protection of the MgO film. The SEY environmental stability of the double-layer structure was significantly improved, and the effect of thickness on SEY was theoretically interpreted. This work makes significant sense for understanding the influence of the environment on the SEY for MgO and Al2O3, which has potential applications in electron multipliers. [ABSTRACT FROM AUTHOR]

The coupling of pyroelectricity, semiconductor, and optical excitation yields the pyro-phototronic effect, which has been extensively utilized in photodetectors. It can also enhance the performance of light energy harvesting nanogenerators. In this work, a pyro-phototronic effect-enhanced MXene/ZnO heterojunction nanogenerator has been successfully demonstrated, which can harvest broadband light energy (from deep UV to near-infrared) and still operate at 200 °C. The morphology of the ZnO layer and the MXene layer's thickness have been further optimized for better light energy harvesting performance. For the optimized heterojunction nanogenerator, the responsivity can be improved from ~0.2 mA/W to ~3.5 mA/W by pyro-phototronic effect, under 0.0974 mW/cm2 365 nm UV illumination. Moreover, the coupling of pyro-phototronic and piezo-phototronic effects in MXene/ZnO heterojunction nanogenerators has been investigated. The results indicate that only a small tensile strain could improve the nanogenerator's performance. The working mechanisms have been carefully analyzed, and the modulation of piezoelectric charges on the Schottky barrier height is found to be the key factor. These results demonstrate the enormous potential of the pyro-phototronic effect in light energy harvesting nanogenerators and illustrate the coupling of pyro-phototronic and piezo-phototronic effects for further performance improvement. [ABSTRACT FROM AUTHOR]