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Additive direct-write microfabrication for MEMS: A review

Kwok Siong TEH

《机械工程前沿（英文）》 2017年第12卷第4期页码 490-509 doi: 10.1007/s11465-017-0484-4

摘要：

Direct-write additive manufacturing refers to a rich and growing repertoire of well-established fabrication techniques that builds solid objects directly from computer-generated solid models without elaborate intermediate fabrication steps. At the macroscale, direct-write techniques such as stereolithography, selective laser sintering, fused deposition modeling ink-jet printing, and laminated object manufacturing have significantly reduced concept-to-product lead time, enabled complex geometries, and importantly, has led to the renaissance in fabrication known as the . The technological premises of all direct-write additive manufacturing are identical—converting computer generated three-dimensional models into layers of two-dimensional planes or slices, which are then reconstructed sequentially into three-dimensional solid objects in a layer-by-layer format. The key differences between the various additive manufacturing techniques are the means of creating the finished layers and the ancillary processes that accompany them. While still at its infancy, direct-write additive manufacturing techniques at the microscale have the potential to significantly lower the barrier-of-entry—in terms of cost, time and training—for the prototyping and fabrication of MEMS parts that have larger dimensions, high aspect ratios, and complex shapes. In recent years, significant advancements in materials chemistry, laser technology, heat and fluid modeling, and control systems have enabled additive manufacturing to achieve higher resolutions at the micrometer and nanometer length scales to be a viable technology for MEMS fabrication. Compared to traditional MEMS processes that rely heavily on expensive equipment and time-consuming steps, direct-write additive manufacturing techniques allow for rapid design-to-prototype realization by limiting or circumventing the need for cleanrooms, photolithography and extensive training. With current direct-write additive manufacturing technologies, it is possible to fabricate unsophisticated micrometer scale structures at adequate resolutions and precisions using materials that range from polymers, metals, ceramics, to composites. In both academia and industry, direct-write additive manufacturing offers extraordinary promises to revolutionize research and development in microfabrication and MEMS technologies. Importantly, direct-write additive manufacturing could appreciably augment current MEMS fabrication technologies, enable faster design-to-product cycle, empower new paradigms in MEMS designs, and critically, encourage wider participation in MEMS research at institutions or for individuals with limited or no access to cleanroom facilities. This article aims to provide a limited review of the current landscape of direct-write additive manufacturing techniques that are potentially applicable for MEMS microfabrication.

关键词： direct-write additive manufacturing microfabrication MEMS

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Electrochemical performance of thermally-grown SiO

X. D. HUANG, X. F. GAN, Q. A. HUANG, J. Z. YANG

《能源前沿（英文）》 2018年第12卷第2期页码 225-232 doi: 10.1007/s11708-018-0556-0

摘要： Direct integration of lithium-ion battery (LIB) with electronic devices on the same Si substrate can significantly miniaturize autonomous micro systems. For achieving direct integration, a barrier layer is essential to be inserted between LIB and the substrate for blocking Li diffusion. In this paper, the feasibility of thermal SiO film as the barrier layer is investigated by electrochemical characterization and X-ray photoelectron spectroscopy (XPS). Due to the negligible side reactions of thermal SiO with electrolyte, the solid electrolyte interphase (SEI) layer formed on the surface of the barrier layer is thin and the SEI content mainly consists of hydrocarbon together with slight polyethylene oxide (PEO), Li PO F , and Li CO . Although 8-nm thermal SiO effectively prevents the substrate from alloying with Li , the whole film changes to Li silicate after electrochemical cycling due to the irreversible chemical reactions of SiO with electrolyte. This degrades the performance of the barrier layer against the electrolyte penetration, thus leading to the existence of Li (in the form of F-Si-Li) and solvent decompositions (with the products of hydrocarbon and PEO) near the barrier layer/substrate interface. Moreover, it is found that the reaction kinetics of thermal SiO with electrolyte decrease significantly with increasing the SiO thickness and no reactions are found in the bulk of the 30-nm SiO film. Therefore, thermal SiO with an appropriate thickness is a promising barrier layer for direct integration.

关键词： autonomous micro system direct integration barrier layer thermal SiO₂ film X-ray photoelectron spectroscopy (XPS)

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Regulation of radicals by hydrogen-donor solvent in direct coal liquefaction

《化学科学与工程前沿（英文）》 2022年第16卷第12期页码 1689-1699 doi: 10.1007/s11705-022-2186-7

摘要： Radicals are important intermediates in direct coal liquefaction. Certain radicals can cause the cleavage of chemical bonds. At high temperatures, radical fragments can be produced by the splitting of large organic molecules, which can break strong chemical bonds through the induction pyrolysis of radicals. The reaction between the formation and annihilation of coal radical fragments and the effect of hydrogen-donor solvents on the radical fragments are discussed in lignite hydrogenolysis. Using the hydroxyl and ether bonds as indicators, the effects of different radicals on the cleavage of chemical bond were investigated employing density functional theory calculations and lignite hydrogenolysis experiments. Results showed that the adjustment of the coal radical fragments could be made by the addition of hydrogen-donor solvents. Results showed that the transition from coal radical fragment to H radical leads to the variation of product distribution. The synergistic mechanism of hydrogen supply and hydrogenolysis of hydrogen-donor solvent was proposed.

关键词： direct coal liquefaction hydrogen-donor solvent induced pyrolysis radical mechanism density functional theory calculations

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Direct acting antiviral-induced dynamic reduction of serum

Tung Huynh, Ke-Qin Hu

《医学前沿（英文）》 2019年第13卷第6期页码 658-666 doi: 10.1007/s11684-019-0707-7

摘要： Direct acting antiviral (DAA) treatments may reduce the elevated α fetoprotein (AFP), but data on how these treatments affect elevated AFP in patients with chronic hepatitis C (CHC) remain insufficient. In the present study, the frequency of baseline AFP elevations and their related factors, AFP dynamics during and after DAA treatment, and factors associated with AFP reduction was assessed. This retrospective study included 141 patients with CHC without hepatocellular carcinoma who received DAA and achieved sustained virological response. The details are as follows: mean post-treatment follow-up was 99 weeks (12–213); mean age, 57.8 years old; 52%, males; 79%, genotype (GT) 1; and 47%, cirrhosis. Pre-treatment AFP elevation (>5.5 ng/mL) was seen in 48.2% patients. On multivariate analysis, baseline AFP>5.5 was associated with the presence of cirrhosis ( =0.001), co-existing non-alcoholic steatohepatitis (NASH) ( = 0.035), and GT 1 ( = 0.029). AFP normalization was seen in 28.2% patients at treatment week 2, in 52% at the end of treatment, and in 73.4% at the end of follow-up. Post-treatment week 24 AFP normalization was associated with the absence of cirrhosis ( = 0.003), Child–Pugh score<6 ( = 0.015), and baseline AFP<10 ( = 0.015). AFP elevation is common in patients with CHC and independently associated with NASH, cirrhosis, and GT 1. DAA treatment resulted in AFP normalization as early as treatment week 2. Post-treatment week 24 AFP normalization is independently associated with the absence of cirrhosis, Child–Pugh score<6, and baseline AFP<10.

关键词： chronic hepatitis C α fetoprotein direct acting antiviral treatment cirrhosis

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Design and analysis of a new high frequency double-servo direct drive rotary valve

Muzhi ZHU,Shengdun ZHAO,Jingxiang LI

《机械工程前沿（英文）》 2016年第11卷第4期页码 344-350 doi: 10.1007/s11465-016-0406-x

摘要：

Researchers have investigated direct drive valve for many years to solve problems, such as fluid force imbalance and switching frequency. The structure of the rotary valve has received considerable research interest because of its favorable dynamic properties and simple structure. This paper studied the high frequency double-servo direct drive rotary valve (DDRV), and proposed a novel structure and drive method satisfying high reversing frequency and adequate quantity of flow. Servo motors are integrated into the valve by the innovative structure, which is designed to equilibrate the unbalanced radial fluid force with the symmetric distributed oil ports. Aside from the fast reversing function of the valve, the DDRV presented high performance in linearity of the flow quantity and valve opening as a result of the fan-shaped flow ports. In addition, a computational fluid dynamics (CFD) method based on Fluent was conducted to verify the flux regulation effect of the height change of the adjustable boss.

关键词： direct drive rotary valve computational fluid dynamics (CFD) flow regulation

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Direct energy rebound effect for road transportation in China

《工程管理前沿（英文）》页码 597-611 doi: 10.1007/s42524-023-0276-y

摘要： The enhancement of energy efficiency stands as the principal avenue for attaining energy conservation and emissions reduction objectives within the realm of road transportation. Nevertheless, it is imperative to acknowledge that these objectives may, in part or in entirety, be offset by the phenomenon known as the energy rebound effect (ERE). To quantify the long-term EREs and short-term EREs specific to China’s road transportation, this study employed panel cointegration and panel error correction models, accounting for asymmetric price effects. The findings reveal the following: The long-term EREs observed in road passenger transportation and road freight transportation range from 13% to 25% and 14% to 48%, respectively; in contrast, the short-term EREs in road passenger transportation and road freight transportation span from 36% to 41% and 3.9% to 32%, respectively. It is noteworthy that the EREs associated with road passenger transportation and road freight transportation represent a partial rebound effect, falling short of reaching the magnitude of a counterproductive backfire effect. This leads to the inference that the upsurge in energy consumption within the road transportation sector cannot be solely attributed to advancements in energy efficiency. Instead, various factors, including income levels, the scale of commodity trade, and industrial structure, exert more substantial facilitating influences. Furthermore, the escalation of fuel prices fails to dampen the demand for energy services, whether in the domain of road passenger transportation or road freight transportation. In light of these conclusions, recommendations are proffered for the formulation of energy efficiency policies pertinent to road transportation.

关键词： road transportation direct energy rebound effect asymmetric price effects panel data model

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Creation and integration mechanism of instrumentation flexible developing system

Xiaoli XU, Qiushuang LIU

《机械工程前沿（英文）》 2011年第6卷第2期页码 235-240 doi: 10.1007/s11465-011-0122-5

摘要：

To solve many key technical problems during the development of modern instrumentation system integration and provide a new mode and fundamental technical equipment for the research and development (R&D) of modern instrumentation products, based on the concept of an instrumentation flexible developing system (IFDS), this paper discusses the creation and open flexible integration mechanism, perfects the integrated supporting environment and integrated system of the flexible interconnection, and constructs the new flexible integrated system. Based on the operation mechanism of the modern instrumentation developing system and the research and optimization of the rapid integration design method, the paper emphasizes the dynamic integrating method of multiple types of knowledge in a modern instrument R&D system, to effectively utilize the rich integrated resource and achieve rapid integration of the system. Applications show that the new IFDS can improve the integration level and efficiency of R&D of the modern instrumentation system, enforce the reliability of the system, shorten the R&D period, and reduce the development costs.

关键词： modern instrumentation developing flexible interconnection flexible integration mechanism rapid integration system dynamic integrating method

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Effect of light scattering on the performance of a direct absorption solar collector

Kwang Hyun WON, Bong Jae LEE

《能源前沿（英文）》 2018年第12卷第1期页码 169-177 doi: 10.1007/s11708-018-0527-5

摘要： Recently, a solar thermal collector often employs nanoparticle suspension to absorb the solar radiation directly by a working fluid as well as to enhance its thermal performance. The collector efficiency of a direct absorption solar collector (DASC) is very sensitive to optical properties of the working fluid, such as absorption and scattering coefficients. Most of the existing studies have neglected particle scattering by assuming that the size of nanoparticle suspension is much smaller than the wavelength of solar radiation (i.e., Rayleigh scattering is applicable). If the nanoparticle suspension is made of metal, however, the scattering cross-section of metallic nanoparticles could be comparable to their absorption cross-section depending on the particle size, especially when the localized surface plasmon (LSP) is excited. Therefore, for the DASC utilizing a plasmonic nanofluid supporting the LSP, light scattering from metallic particle suspension must be taken into account in the thermal analysis. The present study investigates the scattering effect on the thermal performance of the DASC employing plasmonic nanofluid as a working fluid. In the analysis, the Monte Carlo method is employed to numerically solve the radiative transfer equation considering the volume scattering inside the nanofluid. It is found that the light scattering can improve the collector performance if the scattering coefficient of nanofluid is carefully engineered depending on its value of the absorption coefficient.

关键词： direct absorption solar collector plasmonic nanofluid light scattering

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Persistent Integration and Innovation Management Mode and Its Applications in Petroleum Production Engineering

He Liu

《工程管理前沿（英文）》 2015年第2卷第4期页码 339-343 doi: 10.15302/J-FEM-2015055

摘要： This paper proposes a new management mode named the persistent integration and innovation management mode to satisfy the requirements by the fast development at oilfields. Taking engineering philosophy as the guidance and technical innovations in petroleum production engineering as the breaking point, the management mode combines long term production practice at oilfields with modern management methods. The management mode integrates intellectuals, techniques, capital, and information and so on to accomplish global optimization of resource configuration. Sets of new techniques, new methods, new technologies and new equipment in petroleum production engineering have been proposed under the guidance of the management mode, achieving great social and economic benefits.

关键词： integration and innovation engineering philosophy petroleum production engineering Daqing Oilfield

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Optimization and simultaneous heat integration design of a coal-based ethylene glycol refining process

《化学科学与工程前沿（英文）》 2023年第17卷第9期页码 1280-1288 doi: 10.1007/s11705-023-2301-4

摘要： Coal to ethylene glycol still lacks algorithm optimization achievements for distillation sequencing due to high-dimension and strong nonconvexity characteristics, although there are numerous reports on horizontal comparisons and process revamping. This scenario triggers the navigation in this paper into the simultaneous optimization of parameters and heat integration of the coal to ethylene glycol distillation scheme and double-effect superstructure by the self-adapting dynamic differential evolution algorithm. To mitigate the influence of the strong nonconvexity, a redistribution strategy is adopted that forcibly expands the population search domain by exerting external influence and then shrinks it again to judge the global optimal solution. After two redistributive operations under the parallel framework, the total annual cost and CO₂ emissions are 0.61%/1.85% better for the optimized process and 3.74%/14.84% better for the superstructure than the sequential optimization. However, the thermodynamic efficiency of sequential optimization is 11.63% and 10.34% higher than that of simultaneous optimization. This study discloses the unexpected great energy-saving potential for the coal to ethylene glycol process that has long been unknown, as well as the strong ability of the self-adapting dynamic differential evolution algorithm to optimize processes described by the high-dimensional mathematical model.

关键词： ethylene glycol redistribution heat integration optimization parallel framework

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Comparative study of various artificial intelligence approaches applied to direct torque control of induction

Moulay Rachid DOUIRI, Mohamed CHERKAOUI

《能源前沿（英文）》 2013年第7卷第4期页码 456-467 doi: 10.1007/s11708-013-0264-8

摘要： In this paper, three intelligent approaches were proposed, applied to direct torque control (DTC) of induction motor drive to replace conventional hysteresis comparators and selection table, namely fuzzy logic, artificial neural network and adaptive neuro-fuzzy inference system (ANFIS). The simulated results obtained demonstrate the feasibility of the adaptive network-based fuzzy inference system based direct torque control (ANFIS-DTC). Compared with the classical direct torque control, fuzzy logic based direct torque control (FL-DTC), and neural networks based direct torque control (NN-DTC), the proposed ANFIS-based scheme optimizes the electromagnetic torque and stator flux ripples, and incurs much shorter execution times and hence the errors caused by control time delays are minimized. The validity of the proposed methods is confirmed by simulation results.

关键词： adaptive neuro-fuzzy inference system (ANFIS) artificial neural network direct torque control (DTC) fuzzy logic induction motor

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ENTREPRENEURIAL OPPORTUNITY, VALUE EVOLUTION, AND ORGANIZATIONAL INTEGRATION OF PROFESSIONAL FARMER ENTREPRENEURSHIP

《农业科学与工程前沿（英文）》 2023年第10卷第1期页码 135-148 doi: 10.15302/J-FASE-2022464

摘要：

● The choice of a modern agriculture project was found to be rational for professional farmers to reduce interference from non-market factors. The success of this project is due to its capacity to successfully fill the structural hole in the market transaction network.

关键词： Benefit-linked mechanism featured agriculture organizational integration professional farmers rural cooperative structural hole theory

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Biosorption of Direct Black 38 by dried anaerobic granular sludge

WANG Xuejiang, XIA Siqing, ZHAO Jianfu

《环境科学与工程前沿（英文）》 2008年第2卷第2期页码 198-202 doi: 10.1007/s11783-008-0031-y

摘要： The biosorption of Direct Black 38 by dried anaerobic granular sludge in a batch system under specific temperatures and initial pH was investigated. The adsorption reaction is pH dependent with higher removal at low pH. The adsorption equilibrium data fit very well with both Langmuir and Freundlich models in the concentration range of Direct Black 38 at all chosen temperatures. The adsorption parameters show that the adsorption of Direct Black 38 is an endothermic and more effective process at high temperatures. The kinetics of adsorption was found to be second order and adsorption rate constants increased with increasing temperature. Activation energy was determined as 26.8 kJ/mol for the process. This suggests that the adsorption of Direct Black 38 by dried anaerobic granular sludge is chemically controlled.

关键词： Langmuir kJ/mol temperature removal Freundlich

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How aerosol direct effects influence the source contributions to PM

Litao Wang, Joshua S. Fu, Wei Wei, Zhe Wei, Chenchen Meng, Simeng Ma, Jiandong Wang

《环境科学与工程前沿（英文）》 2018年第12卷第3期 doi: 10.1007/s11783-018-1014-2

摘要： Beijing-Tianjin-Hebei area is the most air polluted region in China and the three neighborhood southern Hebei cities, Shijiazhuang, Xingtai, and Handan, are listed in the top ten polluted cities with severe PM pollution. The objective of this paper is to evaluate the impacts of aerosol direct effects on air quality over the southern Hebei cities, as well as the impacts when considering those effects on source apportionment using three dimensional air quality models. The WRF/Chem model was applied over the East Asia and northern China at 36 and 12 km horizontal grid resolutions, respectively, for the period of January 2013, with two sets of simulations with or without aerosol-meteorology feedbacks. The source contributions of power plants, industrial, domestic, transportation, and agriculture are evaluated using the Brute-Force Method (BFM) under the two simulation configurations. Our results indicate that, although the increases in PM concentrations due to those effects over the three southern Hebei cities are only 3%–9% on montly average, they are much more significant under high PM loadings (~50 μg·m when PM concentrations are higher than 400 μg m ). When considering the aerosol feedbacks, the contributions of industrial and domestic sources assessed using the BFM will obviously increase (e.g., from 30%–34% to 32%–37% for industrial), especially under high PM loadings (e.g., from 36%–44% to 43%–47% for domestic when PM >400 μg·m ). Our results imply that the aerosol direct effects should not be ignored during severe pollution episodes, especially in short-term source apportionment using the BFM.

关键词： Aerosol direct effect PM_2.5 Southern Hebei WRF/Chem Haze

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Ultraviolet exposure enhanced silicon direct bonding

Guanglan LIAO, Xuekun ZHANG, Xiaohui LIN, Canghai MA, Lei NIE, Tielin SHI,

《机械工程前沿（英文）》 2010年第5卷第1期页码 87-92 doi: 10.1007/s11465-009-0078-x

摘要： Ultraviolet (UV) exposure, as an additional technique following the traditional wet chemical activation processes, is applied to enhance hydrophilic silicon direct bonding. The effects of UV exposure on silicon wafers’ nano-topography and bonding strength are studied. It is found that the surface roughness of silicon wafers initially decreases and then increases with UV exposure time, and the bonding strength increases and then decreases accordingly. The correlations of annealing temperature and annealing time vs. bonding strength are experimentally explored. Results indicate that the bonding strength increases sharply then gently with increasing annealing temperature and annealing time using UV exposure. Besides, the reliability of silicon direct bonding with UV exposure enhancement after the high/low temperature cycle test, constant temperature and humidity test, vibration test and shock test is investigated. It follows from the results that the bonding strength of silicon wafer pairs with UV exposure decreases after the environmental tests, whereas the residual strength is still higher than that without UV exposure, and the variation trends of bonding strength vs. UV exposure time, annealing temperature and annealing time remain unchanged. Therefore, following the traditional wet chemical activation processes, appropriate UV exposure (about three minutes in this study) is effective and promising to enhance silicon direct bonding.

关键词： ultraviolet (UV) exposure silicon direct bonding bonding strength reliability