Miniaturization of batteries lags behind the success of modern electronic devices. Neither the device volume nor the energy density of microbatteries meets the requirement of microscale electronic devices. The main limitation for pushing the energy density of microbatteries arises from the low mass loading of active materials. However, merely pushing the mass loading through increased electrode thickness is accompanied by the long charge transfer pathway and inferior mechanical properties for long‐term operation. Here, a new spiral microelectrode upon stress‐actuation accomplishes high mass loading but short charge transfer pathways. At a small footprint area of around 1 mm2, a 21‐fold increase of the mass loading is achieved while featuring fast charge transfer at the nanoscale. The spiral microelectrode delivers a maximum area capacity of 1053 µAh cm−2 with a retention of 67% over 50 cycles. Moreover, the energy density of the cylinder microbattery using the spiral microelectrode as the anode reaches 12.6 mWh cm−3 at an ultrasmall volume of 3 mm3. In terms of the device volume and energy density, the cylinder microbattery outperforms most of the current microbattery technologies, and hence provides a new strategy to develop high‐performance microbatteries that can be integrated with miniaturized electronic devices.
The liquid temperature during the preparation of plasma-activated water (PAW) seriously affects the PAW chemical characteristics and its biological effect. In this study, four different temperatures (4°C, 25°C, 40°C, and 70°C) of deionized water are selected as variable parameters to investigate the effect on PAW. The results show that the physicochemical properties and the concentration of reactive oxygen and nitrogen species of PAW are significantly reduced when the temperatures are higher than 25°C; moreover, the above indexes are slightly decreased
Plasma activated water (PAW), as a green and potential technology, plays a significant role in bio-medicine applications. Surface-to-volume ratio of treated liquid during the preparation of PAW seriously affects the PAW chemistry characteristics, and ultimately results in different biological effects. However, that how does the surface-to-volume ratio affect PAW characteristics and anticancer effect induced by PAW is unclear. In this work, the surface-to-volume ratio is regulated to investigate the dynamic variation of chemical characteristics and cell apoptosis. Results display physicochemical properties including pH, ORP, and liquid temperature are varied with nonlinear trend besides conductivity. While the levels of RONS containing NO2
−, NO3
−, H+ are changed with linear trend except H2O2 ONOO− and O
.
2
−. Furthermore, increasing surface-to-volume ratio could effectively accelerate cell apoptosis, enhance intracellular ROS concentration and strengthen anticancer effects. Thus, it is concluded that tuning surface to volume ratio can effectively enhance the reactive species flux into the liquid that leads to remarkable anticancer activity of PAW rather than the surface-to-volume ratio that is directly responsible for the enhanced impact on the cells. Additionally, the possible apoptosis mechanisms linked with RONS are also discussed. Clarifying the relationship between the surface-to-volume ratio and the PAW characteristics is beneficial to much insights into the chemistry nature of PAW and tailoring biological effect caused by PAW.
In this paper, we employ UV absorption spectroscopy to monitor the generation and permeation of reactive oxygen and nitrogen species (RONS) in plasma-activated water (PAW) to revealthe dynamic variation mechanism of RONS chemistry. Parameters including gas impurity, pulse polarity and solution pH value are varied to explore their effects on the absorbance behavior and peak shift of absorption spectra as well as the permeation distribution of RONS. Regarding the absorbance behavior, experimental results show that introducing air and N2 into He working gas would effectively improve RONS absorbance, proportions of about 0.2% air and 0.5% N2 would result in the maximum absorbance, while the addition of O2 would result in a significant decrease in RONS absorbance. Under positive polarity, the RONS absorbance is about 20% higher than that under negative polarity. Changing the solution pH from acidic to alkaline is beneficial in increasing RONS absorbance, indicating that alkaline solution could effectively promote RONS formation. Regarding the characteristic peak shift, different parameter conditions seriously affect the shift of the absorption peak toward low wavelength or high wavelength due to the change in the ratio of the concentration of each component of RONS in PAW. Furthermore, with respect to the permeation distribution of H2O2 and NO2
−, the results show that the addition of O2 would result in the fastest production rate of H2O2 and introducing air and N2 would generate the fastest rate of NO2
− production. Interestingly, the NO2
− permeation distribution displays a ‘columnar mode’ and a ‘filamentous mode’ under positive and negative polarity, respectively. An alkaline solution promotes the formation of NO2
− while having an obvious inhibiting effect on the NO2
− permeation; conversely, an acidic solution has a promotional effect on NO2
−. This study provides a new in-depth understanding of the dynamic evolutionary behavior of RONS in PAW, helping to reveal the network relationship between RONS, and assisting in the development of applications of PAW.
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