Permittivity sensing based on resonance tracking lays the fundamental principle for a variety of biochemical sensors, which has found vast applications in cancer biomarker detection, antigen-antibody analysis, and so on. Driven by continuous promotion of the detection limit, precise environmental control highlights its critical importance. Here, the impacts of liquid level on microwave resonance sensing are investigated, in which a flexible polydimethylsiloxane microfluidic channel and soft tubing are employed to control the liquid under test. The hydraulic pressure affects the effective permittivity of the liquid and the channel material, hence causing extra resonance shift signals. Both contactless and contacting sensing scenarios are studied in numerical simulations and experiments. It is demonstrated that the resonance frequency varies sensitively with the liquid level, and a sensitivity of 343 kHz mm −1 is measured. Meanwhile, a spoof localized surface plasmon resonator and its optimized excitation structure are employed and analyzed for a good figure of merit, addressing the detectability difficulties for high-permittivity and high-loss aqueous solutions. These results provide general guidelines for understanding and controlling the resonance sensors in aqueous environments and help to realize further lower detection limits.
Current fluxgate sensor probe SPICE models constructed by using arc tangent transfer function method and the diode model in fluxgate sensor simulation had some disadvantages which were non convergence, low simulation accuracy, discontinuously adjusted core characteristics and the model couldn’t simulate the hysteresis characteristic. IO characteristics of Schmitt Trigger was similar to the B-H curve of soft magnetic core in shape, for this reason Schmitt trigger was used to construct fluxgate probe SPICE model. HSPICE was used in simulation. Simulation results shown that this model can simulate the real electrical properties of fluxgate probe accurately. This model can be used for fluxgate sensor interface integrated circuit research and fluxgate sensor application, and provide a reference to judge the performance for fluxgate sensors of which core parameters within a certain range.
With development of MEMS pyrotechnics devices such as semiconductor bridge/metal bridges, the energy required to fuze ignition becomes smaller and smaller. The energy needed for traditional short-circuit is far greater than MEMS pyrotechnics devices explosive, and takes a large space of fuze, which does not accord with the smaller trend in fuse volume and ignition energy. This paper describes a MEMS short-circuit fuse based on electro-thermal theory, it has similar volume with MEMS pyrotechnics devices, and the energy required is less than the traditional shorts fuse. This short-circuit fuse has well safety features, short action time, small volume, low cost, and it is suitable to be used in fuse or other areas .
A long term aging treatment at 900oC for 3000h was carried out on a conventional cast nickel base superalloy with standard solution and aging treatment. The microstructural evolution including the phases within grains and at grain boundaries (GBs) during thermal exposure in the alloy was observed using OM and SEM. It was shown that the major phases in the alloy after standard heat treatment were γ' precipitates and coarse blocky MC carbides, both of which were distributed not only within grains but also at GBs. During aging, the size of MC carbides and γ' precipitates both within grains and at GBs increased with increasing aging time. It was found that two characteristics of MC carbide and γ' precipitates evolved with aging time: the one is that the coarsening ratio of carbides and γ' precipitates at GBs were significantly higher than that of carbide and γ' precipitates inside the grains; the other is that the coarsening ratio of carbides was markedly higher than that of γ' precipitates. M6C carbide and η phase initially formed in the edge of MC carbide at the expense of MC carbides and γ' precipitates in the vicinity of MC during the early stage of aging. After 3000h, MC carbides inside the grains were covered by η phase films, while those distributed at GBs were completely decomposed into η phase and M6C particles.
Aromatic thermoset materials have shown great potential applications in various fields owing to their excellent mechanical strengths. However, their poor ductility is still hinders their large-scale applications. In this study, a new class of aromatic thermosets consisting of two types of crosslinks was successfully developed by incorporating the special group imidazole into a type of crosslinked thermoset. One crosslink is constituted of reversible multiple noncovalent interactions containing “face-face” π–π stacking, “point-point” hydrogen bonds, and ion-pair electrostatic interactions, whereas the other is composed of permanent covalent bonds. Most importantly, the synergetic interplay among these reversible multiple noncovalent interactions enables them to evade the restrictions from the aromatic polymer skeletons to proceed with their dynamic dissociating-rebuilding processes, which can timely and effectively dissipate the internal stress. Finally, owing to the coefficient of these two types of crosslinks, a significantly enhanced ductility was successfully obtained on these aromatic thermosets and their tensile strengths were also improved. Such thermosets having simultaneously enhanced strengths and ductility are predicted to be eventually used in a wide range of applications.
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