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Future generations of power converters must be miniaturized to power future electronic devices that are getting smaller and smarter. Monolithic integration is an ideal approach toward compact, efficient, and low-cost converters. This letter addresses two technology gaps in packaging technology and integrated inductor technology using the so-called power interposer technology (PIT). We implemented a step-down power converter to demonstrate PIT. The converter uses two GaN FETs, capacitors, and a gate driver stacked on a 0.28-mm-thick silicon die that hosts a 3D substrate-embedded toroidal microinductor. The converter switches 22 MHz in zero-voltage-switching mode achieving a peak efficiency of 83% at the full load of 1 W. PIT has shown unique technology advantages for future generations of integrated power converters, including high power density, low profile, superior thermal performance, scalability, and heterogeneous integration. Furthermore, PIT holds great commercial potential for high-power-density integrated power converters.

MEMS inductors are used in a wide range of applications in micro- and nanotechnology, including RF MEMS, sensors, power electronics, and Bio-MEMS. Fabrication technologies set the boundary conditions for inductor design and their electrical and mechanical performance. This review provides a comprehensive overview of state-of-the-art MEMS technologies for inductor fabrication, presents recent advances in 3D additive fabrication technologies, and discusses the challenges and opportunities of MEMS inductors for two emerging applications, namely, integrated power electronics and neurotechnologies. Among the four top-down MEMS fabrication approaches, 3D surface micromachining and through-substrate-via (TSV) fabrication technology have been intensively studied to fabricate 3D inductors such as solenoid and toroid in-substrate TSV inductors. While 3D inductors are preferred for their high-quality factor, high power density, and low parasitic capacitance, in-substrate TSV inductors offer an additional unique advantage for 3D system integration and efficient thermal dissipation. These features make in-substrate TSV inductors promising to achieve the ultimate goal of monolithically integrated power converters. From another perspective, 3D bottom-up additive techniques such as ice lithography have great potential for fabricating inductors with geometries and specifications that are very challenging to achieve with established MEMS technologies. Finally, we discuss inspiring and emerging research opportunities for MEMS inductors.

The linear regression model as well as the time series model is applied in many fields, in which the mean of the dependent variable is one function of the mean of the independent variables. However, to consider the regression model following in the Classical Statistics (the Frequent Statistics), it means that the parameters are the constants, in many situations, the regression model does not describe the fluctuation of both the dependent variable and the independent variables. Therefore, we need to modify the parameters following the random variable form, not the constant form, like as the regression in Bayesian Statistics. The other side, when the parameters considered as the random variables, computations in the regression model becomes very complex, because we need to compute the product of the probability distributions. So, we must evaluate about to vary of the variables' probability distributions not only the normal distribution, the Student distribution t, the Poisson distribution, the binomial distribution… In this paper, we estimated the dependent variable's probability distribution form through the simple Bayesian regression model in cases having many the probability distribution forms of the independent variable. In addition, we apply the results to real stock price data, proving that the most appropriate probability distribution with the data is a mixture of probability distributions, not a single normal distribution.

The integration of power inductors is a roadblock in realizing highly miniaturized power supply in package (PSiP) and power supply on chip. Inductors in such power systems are used for energy storage and filtering, but they dominate in size and loss. This paper presents a novel three-dimensional in-silicon through-silicon via (TSV) magnetic-core toroidal inductor for PSiP. The magnetic powder based core is embedded into a TSV air-core inductor using a casting method. The unique air-core inductor design with a hollow core and suspended windings enables a complete core filling with microscale magnetic powders. The proposed casting method is simple, scalable, and generic for a wide range of magnetic powders. TSV magnetic-core inductors are fabricated in a compact size of 2.4 mm × 2.4 mm × 0.28 mm with the core content varying from 63 to 88 wt% of soft ferrite NiZn powders. The TSV magnetic-core toroidal inductors are fabricated and electrically characterized. Small-signal measurements show a threefold higher inductance of 112 nH and a 30% higher quality factor of 14.3 at 12.5 MHz for magnetic-core inductors compared with similar TSV air-core inductors. The small-signal measurement results are verified by the modeled results. The total core loss is characterized by large-signal measurements. A suitable inductor is implemented in a 12-MHz buck converter that operates in a zero-voltage-switching mode. The converter achieves a peak efficiency of 71.6% and an output power of 2.4 W while converting 12 to 5 Vdc.

Miniaturization of power supplies is required for future intelligent electronic systems, e.g., Internet-of-Things devices. Inductors play an essential role, and they are by far the most bulky and expensive components in power supplies. This paper presents a miniaturized microelectromechanical system (MEMS) inductor and its performance in a very high-frequency (VHF) power converter. The MEMS inductor is a silicon-embedded air-core toroidal inductor, and it is constructed with through-silicon vias, suspended copper windings, silicon fixtures, and a silicon support die. The air-core inductors outperform the silicon-core inductors with higher quality factor at higher frequency. This is verified by small-signal measurements. A 20-turn air-core inductor achieved an inductance of 44.6 nH and a quality factor of 13.3 at 33 MHz, while a silicon-core inductor with the same geometry has a quality factor of 9 at 20 MHz. A dc–dc class-E boost converter is designed and implemented using the fabricated MEMS air-core inductor and a high-performance 65-V gallium nitride field-effect transistor. The VHF converter achieved a peak efficiency of 78% at an input voltage of 6.5 $\text{V}_{\mathrm {DC}}$ . The MEMS inductor can carry 1-A root-mean-square ac current at 33 MHz and delivers 10.5 W to the output.

Al2O3 thin-film deposited by atomic layer deposition is an attractive plasma etch mask for Micro and Nano Electro-Mechanical Systems (MEMS and NEMS). 20-nm-thick Al2O3 mask enables through silicon wafer plasma etching. Al2O3 is also an excellent etch mask for other important MEMS materials such as silicon dioxide, silicon nitride, and diamond. In this report, we systematically study nanoscale plasma etching of Al2O3 with electron beam lithography and deep UV resist masks. The gas composition and pressure were tuned for optimal etching, and redeposition conditions were mapped. With a BCl3 and Ar plasma chemistry, the Al2O3 etch rate was controlled to between 0.1 and 1 nm/min. The etch selectivity of Al2O3 over resist ranged between 1:4 to 1:1. Etch-rate was linearly dependent on the substrate bias power. The etch profile angle can be controlled to between 20 and 82° that almost preserved the resist profile angle. For Al2O3 patterned with deep UV lithography, the smallest structures were 220 nm. For electron beam lithography patterns, the smallest gratings were 18-nm-wide with 50-nm-pitch. Using alumina as a hard mask, we show aspect ratio of 7-10 for subsequent silicon plasma etching, and we etched diamond nanopillars in single crystalline diamond. Based on these studies, we provide guidelines for alumina plasma etching on the nanoscale.

Analysts generally use closing price and normal distribution assumption for a model’s distribution in financial analysis. However, stock price fluctuation is reflected by a set of four values, namely opening, highest, lowest and closing prices. We therefore include the highest and the lowest prices to take into account more information in the hope of ending up with a more exact result as data contains a ranges of values instead of one only (i.e. the data is a form of fuzzy number). Moreover, the assumption that data is normally distributed is not always satisfied and Jacque Bera or Chi square tests are often employed to test the data’s normality. The tests require the use of pvalue which is quite controversial at present. This paper employs fuzzy Bayes point estimator to choose the most suitable distribution. On a sample of 9 stocks with large capitalization in Vietnam from their listed dates until November 06, 2015, we found that some stocks have prices distributed more reasonably than normal distribution and some are not.

A high level of mutation enables the influenza A virus to resist antibiotics previously effective against the influenza A virus. A portion of the structure of hemagglutinin HA is assumed to be well-conserved to maintain its role in cellular fusion, and the structure tends to be more conserved than sequence. We designed peptide inhibitors to target the conserved residues on the HA surface, which were identified based on structural alignment. Most of the conserved and strongly similar residues are located in the receptor-binding and esterase regions on the HA1 domain In a later step, fragments of anti-HA antibodies were gathered and screened for the binding ability to the found conserved residues. As a result, Methionine amino acid got the best docking score within the −2.8 Å radius of Van der Waals when it is interacting with Tyrosine, Arginine, and Glutamic acid. Then, the binding affinity and spectrum of the fragments were enhanced by grafting hotspot amino acid into the fragments to form peptide inhibitors. Our peptide inhibitor was able to form in silico contact with a structurally conserved region across H1, H2, and H3 HA, with the binding site at the boundary between HA1 and HA2 domains, spreading across different monomers, suggesting a new target for designing broad-spectrum antibody and vaccine. This research presents an affordable method to design broad-spectrum peptide inhibitors using fragments of an antibody as a scaffold.

The effects of microencapsulated phase-change materials (MPCM) on the rheological properties of a geopolymer paste (GPP) were investigated. In order to quantify the time-dependent viscosity increase of the geopolymer paste containing MPCM (GPP-MPCM), a new rheological model was successfully developed. Three different MPCMs were compared in order to examine the effect of the hygroscopic nature of the microcapsule shells and the size distribution of the microcapsules. In addition, the effect of microcapsule concentration was investigated. It was found that microcapsules with polar functional groups on the shells affect the viscosity and the geopolymerization reaction of the geopolymer paste much more than microcapsules with hydrophobic shells. In addition, aggregated microcapsules influence the viscosities less than unaggregated micro capsules.

Electron-beam lithography (EBL) is the backbone technology for patterning nanostructures and manufacturing nanodevices. It involves processing and handling synthetic resins in several steps, each requiring optimization and dedicated instrumentation in cleanroom environments. Here, we show that simple organic molecules, e.g. alcohols, condensed to form thin-films at low temperature demonstrate resist-like capabilities for EBL applications and beyond. The entire lithographic process takes place in a single instrument, and avoids exposing users to chemicals and the need of cleanrooms. Unlike EBL that requires large samples with optically flat surfaces, we patterned on fragile membranes only 5 nm-thin, and 2 × 2 mm2 diamond samples. We created patterns on the nanometer to sub-millimeter scale, as well as three-dimensional structures by stacking layers of frozen organic molecules. Finally, using plasma etching, the organic ice resist (OIR) patterns are used to structure the underlying material, and thus enabl...

Hypothesis testing, which has been studied since the time of Fisher, Neyman and Pearson, is a fundamentally important task in statistics. As of now, the classical p-value has been extensively used for more than half a century. However, a number of serious drawbacks have been documented over the years. With the flourish of data science recently, there is a growing demand for better approaches. In this paper, we propose a novel method for hypothesis testing based on the inferential models by Martin and Liu. Our approach not only avoids all major weaknesses of the classical p-value but also provides considerable flexibility in perform testing. Besides, in this regard, the inferential model has some advantages over the popular Bayesian framework.