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COVID-19 is still pandemic in the world although it has lasted for more than two years, in situ real-time disinfection of curved surfaces in public places is extremely urgent. A flexible plasma film based on surface dielectric barrier discharge is proposed in this study. In situ disinfection effect and the influence of curvature on the performance are studied. The results showed that the film could in situ inactivate a variety of pathogens. Specifically, 10 min plasma treatment results in a log reduction of 3.10, 3.42, and 3.03 for Escherichia coli, Staphylococcus aureus, and vesicular stomatitis virus, respectively. The discharge power and disinfection effect of the film are independent of the curvature, which proves that it can be used for in situ disinfection of curved surfaces. It is speculated that the combined effects of a strong electric field and radical etching physical damage as well as the chemical damage of reactive oxygen and nitrogen species to the protein are the main reasons for the inactivation of pathogens. The inhibition of the film to Omicron type SARS-CoV-2 pseudovirus is 99.3%, and the killing rate to natural bacteria is 94.3%. The film can run for at least 10 h without significant reduction in disinfection effect. In addition, large-scale and digitalization increase the practical potential of a disinfection film. In conclusion, this film is expected to realize in situ real-time disinfection of curved surfaces such as the buttons of the elevator or instrument and door handles, which is of great significance in blocking the spread of COVID-19.

What precludes lowering the supply voltage and overall power consumption of the transistor is the infamous Boltzmann tyranny, a fundamental thermionic limit preventing the subthreshold slope (SS) of the transistor from being lower than 60 mV dec−1 at room temperature (RT). Internal voltage amplification through the use of an additional threshold switch (TS) serially connected to the transistor channel has been shown to be highly effective to break the Boltzmann barrier. This approach, however, is typically heterogeneous by employing TS materials that are foreign to the transistor. Recently, semiconducting tellurium (Te) has gained considerable research interest for its use as an emerging low-dimensional p-type channel material with high hole mobility, air-stability, and the ability to be processed at near ambient temperature. In this work, we unveil a hidden advantage of Te for a steep-slope transistor in which Te serves as the channel material and the TS material at the same time. In a homogeneous and compact device architecture, RT-SS lower than 30 mV dec−1 can be achieved. This is enabled by a combination of unique electrical–electrochemical–thermal properties in Te. This work augments the functionality of Te and provides a low-power transistor solution.

We demonstrate the formation and transition behaviors of a microplasma around microstructure arrays at different gas pressures via two-dimensional particle-in-cell/Monte Carlo collision simulations. It is found that the microdischarge occurs outside the cathode microcavities at the lowest pressure and starts penetrating the microcavities with a curved sheath edge as the pressure increases. At higher pressure, coupled periodic microhollow cathode discharges (MHCDs) are formed inside the microcavities. Further increasing the gas pressure results in the disappearance of the MHCDs, and the dominant discharge shifts outside of the microcavity, locating above the protrusion tips. The effect of the space charge shielding on the discharge and the conditions for MHCD formation are discussed. The macroscopic discharge parameter scalings with the gas pressure and the electron kinetics are also examined. The results are helpful for deeply understanding the microplasma formation with nonplanar electrodes, which inform the scaling, design, and optimization of microplasma array devices across a wide range of pressure regimes in practical applications.

We develop a hierarchical acoustic metamaterial with ultra-broadband sound absorption and promising applications at high temperatures as a super sound absorber. The proposed metamaterial is constructed through tailoring structural configurations by vertex-based hierarchy. The hierarchical design enables the acoustic metamaterial to achieve an excellent successive absorption spectrum in the low- to mid-frequency range from 0.58 kHz to 2.04 kHz in the first order and 0.64 kHz to 3.42 kHz in the second order, respectively. The sound absorption performance at high temperatures is predicted by means of theoretical and numerical approaches, and the models are validated by experimental measurements at room temperature. This work provides insight and opportunities into the role of structural hierarchy in designing acoustic metamaterials equipped with extraordinary absorption properties, illustrating an unprecedented capability of the hierarchical acoustic metamaterial.

A flashover switch inserted between the cathode and wire end was used to enhance the deposition energy into an exploding wire in vacuum. It was found that this flashover switch can play two roles. The first one is to reduce the rise time of the current pulse, the second and more important one to greatly improve the surface radial electric field and suppress the electronic emission that is responsible for triggering the surface breakdown of the exploding wire. Only when the flashover switch is on the cathode, the second one can take effect and result in a much higher deposition energy. In this case, the deposition energy could increase by ∼three times (3.4 eV/atom–12 eV/atom) under the negative current pulse and by ∼two times (5.7 eV/atom–13 eV/atom) under the positive one, and fully vaporized wire core was observed with laser interferometry.

The recovery of the gas density and the hold-off voltage of a spark gap after breakdown were investigated with Mach–Zehnder interferometry and two-pulse method, respectively. It was shown that the gas density in a 2.7 mm gap filled with atmospheric nitrogen almost fully recovers at t=50 ms but the breakdown voltage of the gap only recovers to its static hold-off voltage, about 21.4% of its original overvolted breakdown voltage. The mechanisms for the delayed recovery of the ability to be overvolted were discussed.

The electron density in a microwave plasma torch at atmospheric pressure was measured with a Mach–Zehnder interferometer. The electron density is on the order of 1017/cm3, one order higher than that deduced from the Stark broadening of spectral lines, and increases with the increase in the microwave power. The spatial distribution of the electron density was obtained. The highest electron density locates at the symmetrical axis of the plasma torch and decreases radially. It was found that the electron density fluctuates within a range of 0.3 with the time under the same experimental conditions.

The experiment of dielectric barrier discharge in a 2mm air gap shows that the pressure range of a uniform discharge using polytetrafluoroethylene as barrier is much wider than that using quartz or alumina. The parameters of the charge trapped on the surface of these three dielectric barriers were obtained by surface charge measurement and thermally stimulated current measurement. It was found that surface charge trapping has much influence on the uniform discharge, i.e., the seed electrons necessary for uniform discharge may be produced by the desorption of the absorbed electrons in the shallow trap with energy level lower than 1eV.

The radial evolution of dielectric barrier discharge in helium at atmospheric pressure was studied by taking end-view photographs of the discharge during one current pulse using a fast-gated intensified charge coupled device. The photographs were transformed into three-dimensional images that make the radial evolution of the discharge more visualized. It was found that the discharge begins with a weak Townsend discharge covering the entire electrode surface, develops much more rapidly in the central part where the electric field is higher, and spreads radially outward.

Dielectric barrier discharge in helium at atmospheric pressure was studied by taking fast images of the discharge during one current pulse using an intensified charge couple device. It was observed that there appears a weakly luminous layer close to the anode at the very beginning of the discharge, then the luminous area gradually expands into the entire gap as the anode layer moves toward the cathode, and finally a highly luminous layer forms close to the cathode at the time around the maximum of the current pulse. The evolution of the discharge pattern indicates a transition from Townsend discharge to glow discharge.