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991.
Direct Transfer Printing with Metal Oxide Layers for Fabricating Flexible Nanowire Devices
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Sang Hoon Lee Tae Il Lee Moon‐Ho Ham Su Jeong Lee Ji Hyeon Park Yun Cheol Kim Pranab Biswas Jae Min Myoung 《Advanced functional materials》2015,25(44):6921-6926
A direct printing method for fabricating devices by using metal oxide transfer layers instead of conventional transfer media such as polydimethylsiloxane is presented. Metal oxides are not damaged by organic solvents; therefore, electrodes with gaps less than 2 μm can be defined on a metal oxide transfer layer through photolithography. In order to determine a suitable metal oxide for use as transfer layer, the surface energies of various metal oxides are measured, and Au layers deposited on these oxides are transferred onto polyvinylphenol (PVP). To verify the feasibility of our approach, Au source–drain electrodes on transfer layers and Si nanowires (NWs) addressed by the dielectrophoretic (DEP) alignment process are transferred onto rigid and flexible PVP‐coated substrates. Based on transfer test and DEP process, Al2O3 is determined to be the best transfer layer. Finally, Si NWs field effect transistors (FETs) are fabricated on a rigid Si substrate and a flexible polyimide film. As the channel length decreases from 3.442 to 1.767 μm, the mobility of FET on the Si substrate increases from 127.61 ± 37.64 to 181.60 ± 23.73 cm2 V?1 s?1. Furthermore, the flexible Si NWs FETs fabricated through this process show enhanced electrical properties with an increasing number of bending cycles. 相似文献
992.
Thermally Controlled,Patterned Graphene Transfer Printing for Transparent and Wearable Electronic/Optoelectronic System
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Moon Kee Choi Inhyuk Park Dong Chan Kim Eehyung Joh Ok Kyu Park Jaemin Kim Myungbin Kim Changsoon Choi Jiwoong Yang Kyoung Won Cho Jae‐Ho Hwang Jwa‐Min Nam Taeghwan Hyeon Ji Hoon Kim Dae‐Hyeong Kim 《Advanced functional materials》2015,25(46):7109-7118
Graphene has been highlighted as a platform material in transparent electronics and optoelectronics, including flexible and stretchable ones, due to its unique properties such as optical transparency, mechanical softness, ultrathin thickness, and high carrier mobility. Despite huge research efforts for graphene‐based electronic/optoelectronic devices, there are remaining challenges in terms of their seamless integration, such as the high‐quality contact formation, precise alignment of micrometer‐scale patterns, and control of interfacial‐adhesion/local‐resistance. Here, a thermally controlled transfer printing technique that allows multiple patterned‐graphene transfers at desired locations is presented. Using the thermal‐expansion mismatch between the viscoelastic sacrificial layer and the elastic stamp, a “heating and cooling” process precisely positions patterned graphene layers on various substrates, including graphene prepatterns, hydrophilic surfaces, and superhydrophobic surfaces, with high transfer yields. A detailed theoretical analysis of underlying physics/mechanics of this approach is also described. The proposed transfer printing successfully integrates graphene‐based stretchable sensors, actuators, light‐emitting diodes, and other electronics in one platform, paving the way toward transparent and wearable multifunctional electronic systems. 相似文献
993.
Batteries: In Situ Formation of Conductive Metal Sulfide Domain in Metal Oxide Matrix: An Efficient Way to Improve the Electrochemical Activity of Semiconducting Metal Oxide (Adv. Funct. Mater. 31/2015)
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In Young Kim Jiyoon Seo Seung Mi Oh Sharad B. Patil Seong‐Ju Hwang 《Advanced functional materials》2015,25(31):4921-4921
994.
“Multipoint Force Feedback” Leveling of Massively Parallel Tip Arrays in Scanning Probe Lithography
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Hanaul Noh Goo‐Eun Jung Sukhyun Kim Seong‐Hun Yun Ahjin Jo Se‐Jong Kahng Nam‐Joon Cho Sang‐Joon Cho 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(35):4526-4531
Nanoscale patterning with massively parallel 2D array tips is of significant interest in scanning probe lithography. A challenging task for tip‐based large area nanolithography is maintaining parallel tip arrays at the same contact point with a sample substrate in order to pattern a uniform array. Here, polymer pen lithography is demonstrated with a novel leveling method to account for the magnitude and direction of the total applied force of tip arrays by a multipoint force sensing structure integrated into the tip holder. This high‐precision approach results in a 0.001° slope of feature edge length variation over 1 cm wide tip arrays. The position sensitive leveling operates in a fully automated manner and is applicable to recently developed scanning probe lithography techniques of various kinds which can enable “desktop nanofabrication.” 相似文献
995.
Yun Hee Chang Tae Soo Bae Shin Ki Kim Mu Seong Mun Wan-Hee Lee 《International Journal of Precision Engineering and Manufacturing》2011,12(1):129-134
The incidence of osteoarthritis for lower limb amputees, especially unilateral transfemoral amputees, was higher than that
of transtibial amputees. Considering level of amputation and bilateral load asymmetry, we could assumed that joint moments
in the coronal plane during gait were highly related to the risk of osteoarthritis. Therefore, this study aimed to examine
the hip and knee adduction moments in the coronal plane in persons with unilateral transfemoral amputation during walking
through gait analysis. The subjects were 12 unilateral transfemoral amputees and 21 healthy persons. Three-dimensional motion
analysis was measured bilaterally from 33 persons during walking to calculate temporal-spatial parameters and joint moments.
The analysis compared the prosthetic side and the intact side of the amputee group and then analyzed the moment between both
the intact sides of the transfemoral amputee group and the healthy persons. The results showed that the intact knee adduction
moment of amputees increased by 32% compared to the prosthetic side and more than twice compared to the control group at terminal
stance. But the bilateral hip adduction moment was decreased compared to the control group (p<0.05). Therefore it is expected
that the higher knee adduction moment on the intact side may cause secondary complication to unilateral transfemoral amputees,
but it is difficult to make connection with hip osteoarthritis. 相似文献
996.
This paper has developed a complete two-phase model of a proton exchange membrane (PEM) fuel cell by considering fluid flow, heat transfer and current simultaneously. In fluid flow, two momentum equations governing separately the gaseous-mixture velocity (ug) and the liquid-water velocity (uw) illustrate the behaviors of the two-phase flow in a porous electrode. Correlations for the capillary pressure and the saturation level connect the above two-fluid transports. In heat transfer, a local thermal non-equilibrium (LTNE) model accounting for intrinsic heat transfer between the reactant fluids and the solid matrices depicts the interactions between the reactant-fluid temperature (Tf) and the solid-matrix temperature (Ts). The irreversibility heating due to electrochemical reactions, Joule heating arising from Ohmic resistance, and latent heat of water condensation/evaporation are considered in the present non-isothermal model. In current, Ohm's law is applied to yield the conservations in ionic current (im) and electronic current (is) in the catalyst layer. The Butler–Volmer correlation describes the relation of the potential difference (overpotential) and the transfer current between the electrolyte (such as Nafion™) and the catalyst (such as Pt/C). 相似文献
997.
Examined were the effects of the clamping pressure on the performance of a proton exchange membrane (PEM) fuel cell. The electro-physical properties of the gas diffusion layer (GDL) such as porosity, gas permeability, electrical resistance and thickness were measured using a special-designed test rig under various clamping pressure levels. Correlations for the gas permeability of the GDL were developed in terms of the clamping pressure. In addition, the contact resistance between the GDL and the bipolar (graphite) plate was measured under various clamping pressures. Results showed that at the low clamping pressure levels (e.g. <5 bar) increasing the clamping pressure reduces the interfacial resistance between the bipolar plate and the GDL that enhances the electrochemical performance of a PEM fuel cell. In contrast, at the high clamping pressure levels (e.g. >10 bar), increasing the clamping pressure not only reduces the above Ohmic resistance but also narrows down the diffusion path for mass transfer from gas channels to the catalyst layers. Comprising the above two effects did not promote the power density too much but reduce the mass-transfer limitation for high current density. 相似文献
998.
Yur-Tsai LinYoung-Ming Hwang Chi-Chuan Wang 《International Journal of Heat and Mass Transfer》2002,45(25):5035-5044
An experimental study reporting the airside performance of the herringbone wavy fin geometry in wet conditions is conducted. In the visualization of the condensate flow pattern, a very special “locally dry” spot of the corrugation wavy channel having a corrugation angle of 15° and a fin spacing of 8.4 mm is seen. This phenomenon is related to the recirculation of the airflow across the apex. Conversely, this phenomenon is not so clearly seen either for a fin pitch of 2.6 mm with a corrugation angle of 15° or a corrugation angle of 25°. Flow visualization of the non-uniform distribution of the condensation in the facets results in a dependence between axial length and friction factor. Based on the present test results, airside performance in terms of Nusselt number and Fanning friction factor for the present herringbone wavy fin geometry in wet conditions are developed. The mean deviations of the proposed correlations are 2.52% and 4.81%, respectively. 相似文献
999.
Bing-Joe Hwang Shao-Kang Hu Ching-Hsiang Chen Chun-Yu Chen Hwo-Shuenn Sheu 《Journal of power sources》2007
The structural changes of pristine and ZrO2-coated LiMn0.5Ni0.5O2 cathode materials were investigated by using in situ X-ray diffraction (XRD) during charging process. An obviously solid solution phase transition from a hexagonal structure (H1) to another hexagonal structure (H2) was observed during the charging process at a constant current of 0.3 mA in the potential range of 2.5–5.7 V. The second hexagonal structure has a shorter a-axis and a longer c-axis before the crystal collapse. Before the structure collapses the c-axis length increases to maximum and then significantly decreases to 14.1 Å. The c-axis length of the pristine and ZrO2-coated LiMn0.5Ni0.5O2 increases to the maximum at the charge capacity of 119.2 and 180.9 mAh g−1, respectively. It can be concluded that the ZrO2 coating can strongly stabilize the crystal structure of the LiMn0.5Ni0.5O2 compound from the comparison of the lattice parameter variations between the pristine and the ZrO2-coated LiMn0.5Ni0.5O2 compounds upon charge. The potential fluctuation resulting from the decomposition of electrolytes starts at the charge capacity of around 200 and 260 mAh g−1 for the pristine and ZrO2-coated LiMn0.5Ni0.5O2, respectively. It suggests that the ZrO2 coating layer can impede the reaction between the cathode material and electrolyte. 相似文献
1000.
Phase evolution during the synthesis of Cu(InGa)Se2 from glass/Mo/(In1 − xGax)2Se3/CuSe bilayer precursors were investigated by in-situ high-temperature X-ray diffraction. With Se overpressure, CuSe was transformed to CuSe2 at 220 °C. The CuSe2 phase returned to CuSe by releasing Se at its peritectic point of 330 °C, where the formation of Cu(InGa)Se2 phase was initiated as well. Rapid thermal processing of bilayer precursors showed the potential of fast formation of Cu(InGa)Se2 within 2–5 min reaction with fairly uniform Ga and In depth profile. Further annealing with Se overpressure caused the formation of MoSe2 at the interface of Mo and Cu(InGa)Se2. 相似文献