The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Ye Tian - One of the best experts on this subject based on the ideXlab platform.
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BioinspiredSelf-Healing Liquid Films for UltradurableElectronics
ACS Nano, 2019Co-Authors: Weining Miao, Dianyu Wang, Jiayue Tang, Shuang Zheng, Can Wang, Ye TianAbstract:Resistive strain sensors play a crucial role in the development of flexible and stretchable electronics because of their excellent sensitivity and conformability. However, such sensors suffer from poor durability because of the low adhesion strength between the solid conductive layer and polymer and the irreparable dry friction inside the conventional solid conductive layers. Here, inspired from the structures and excellent abrasion resistance of tear Films on animal corneas, we demonstrate ultradurable strain sensors based on uniform self-healing wear-free Liquid Films formed on biomimetic microvilli made from modified polydimethylsiloxane (PDMS). Ethanol solutions containing ionic Liquids (ILs) are added to PDMS microvilli, which are superlyophilic due to the surface chemistry and special structures. During evaporation, ILs are driven upward by Laplace pressure and join into continuous conductive Films. As the sensing layer, when repeatedly stretched and released, the capillary-stabilized Liquid film is...
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Bioinspired Self-Healing Liquid Films for Ultradurable Electronics
ACS Nano, 2019Co-Authors: Weining Miao, Dianyu Wang, Jiayue Tang, Shuang Zheng, Can Wang, Ye TianAbstract:Resistive strain sensors play a crucial role in the development of flexible and stretchable electronics because of their excellent sensitivity and conformability. However, such sensors suffer from poor durability because of the low adhesion strength between the solid conductive layer and polymer and the irreparable dry friction inside the conventional solid conductive layers. Here, inspired from the structures and excellent abrasion resistance of tear Films on animal corneas, we demonstrate ultradurable strain sensors based on uniform self-healing wear-free Liquid Films formed on biomimetic microvilli made from modified polydimethylsiloxane (PDMS). Ethanol solutions containing ionic Liquids (ILs) are added to PDMS microvilli, which are superlyophilic due to the surface chemistry and special structures. During evaporation, ILs are driven upward by Laplace pressure and join into continuous conductive Films. As the sensing layer, when repeatedly stretched and released, the capillary-stabilized Liquid film is...
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Bioinspired Self-Healing Liquid Films for Ultradurable Electronics
ACS Nano, 2019Co-Authors: Weining Miao, Dianyu Wang, Jiayue Tang, Shuang Zheng, Can Wang, Ye TianAbstract:Resistive strain sensors play a crucial role in the development of flexible and stretchable electronics because of their excellent sensitivity and conformability. However, such sensors suffer from poor durability because of the low adhesion strength between the solid conductive layer and polymer and the irreparable dry friction inside the conventional solid conductive layers. Here, inspired from the structures and excellent abrasion resistance of tear Films on animal corneas, we demonstrate ultradurable strain sensors based on uniform self-healing wear-free Liquid Films formed on biomimetic microvilli made from modified polydimethylsiloxane (PDMS). Ethanol solutions containing ionic Liquids (ILs) are added to PDMS microvilli, which are superlyophilic due to the surface chemistry and special structures. During evaporation, ILs are driven upward by Laplace pressure and join into continuous conductive Films. As the sensing layer, when repeatedly stretched and released, the capillary-stabilized Liquid film is...
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Bioinspired Self-Healing Liquid Films for Ultradurable Electronics
2019Co-Authors: Weining Miao, Dianyu Wang, Jiayue Tang, Shuang Zheng, Can Wang, Zemin Liu, Zhongpeng Zhu, He Liu, Li Wen, Ye TianAbstract:Resistive strain sensors play a crucial role in the development of flexible and stretchable electronics because of their excellent sensitivity and conformability. However, such sensors suffer from poor durability because of the low adhesion strength between the solid conductive layer and polymer and the irreparable dry friction inside the conventional solid conductive layers. Here, inspired from the structures and excellent abrasion resistance of tear Films on animal corneas, we demonstrate ultradurable strain sensors based on uniform self-healing wear-free Liquid Films formed on biomimetic microvilli made from modified polydimethylsiloxane (PDMS). Ethanol solutions containing ionic Liquids (ILs) are added to PDMS microvilli, which are superlyophilic due to the surface chemistry and special structures. During evaporation, ILs are driven upward by Laplace pressure and join into continuous conductive Films. As the sensing layer, when repeatedly stretched and released, the capillary-stabilized Liquid film is lossless because of wet friction, and the cracks will recover completely after release due to the capillary-force-induced self-healing capability, allowing the strain sensors to exhibit high durability of over 22 500 loading–unloading cycles. This work presents an approach for the construction of ultradurable electronics
Oleg Kabov - One of the best experts on this subject based on the ideXlab platform.
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an experimental study of high heat flux removal by shear driven Liquid Films
Epj Web of Conferences, 2017Co-Authors: D V Zaitsev, Egor Tkachenko, Oleg KabovAbstract:Intensively evaporating Liquid Films, moving under the friction of a co-current gas flow in a mini-channel (shear-driven Liquid Films), are promising for the use in cooling systems of modern semiconductor devices with high local heat release. In this work, the effect of various parameters, such as the Liquid and gas flow rates and channel height, on the critical heat flux in the locally heated shear-driven water film has been studied. A record value of the critical heat flux of 1200 W/cm2 has been achieved in experiments. Heat leaks to the substrate and heat losses to the atmosphere in total do not exceed 25% for the heat flux above 400 W/cm2 . Comparison of the critical heat fluxes for the shear-driven Liquid film and for flow boiling in a minichannel shows that the critical heat flux is an order of magnitude higher for the shear-driven Liquid film. This confirms the prospect of using shear-driven Liquid Films in the modern high-efficient cooling systems.
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Dry spot growth criterion for isothermal Liquid Films on a horizontal substrate
Thermophysics and Aeromechanics, 2017Co-Authors: L. I. Maltsev, Yu. S. Podzharov, Oleg KabovAbstract:A criterion was elaborated for the phenomenon of dry spot evolution in isothermal Liquid Films on a horizontal substrate. The formulas are presented for gravity force and surface tension acting upon an element of the rim around the dry spot. The forces balance gives the evolution of initial dry spot: to expand or to contract.
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stability and break up of thin Liquid Films on patterned and structured surfaces
Advances in Colloid and Interface Science, 2016Co-Authors: Vladimir S Ajaev, Elizaveta Ya Gatapova, Oleg KabovAbstract:Solid surfaces with chemical patterning or topographical structure have attracted attention due to many potential applications such as manufacture of flexible electronics, microfluidic devices, microscale cooling systems, as well as development of self-cleaning, antifogging, and antimicrobial surfaces. In many configurations involving patterned or structured surfaces, Liquid Films are in contact with such solid surfaces and the issue of film stability becomes important. Studies of stability in this context have been largely focused on specific applications and often not connected to each other. The purpose of the present review is to provide a unified view of the topic of stability and rupture of Liquid Films on patterned and structured surfaces, with particular focus on common mathematical methods, such as lubrication approximation for the Liquid flow, bifurcation analysis, and Floquet theory, which can be used for a wide variety of problems. The physical mechanisms of the instability discussed include disjoining pressure, thermocapillarity, and classical hydrodynamic instability of gravity-driven flows. Motion of a contact line formed after the film rupture is also discussed, with emphasis on how the receding contact angle is expected to depend on the small-scale properties of the substrate.
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evaporation and flow dynamics of thin shear driven Liquid Films in microgap channels
Experimental Thermal and Fluid Science, 2011Co-Authors: Oleg Kabov, D V Zaitsev, Vyacheslav Cheverda, Avram BarcohenAbstract:Abstract Thin and ultra-thin shear-driven Liquid Films in a narrow channel are a promising candidate for the thermal management of advanced semiconductor devices in earth and space applications. Such flows experience complex, and as yet poorly understood, two-phase flow phenomena requiring significant advances in fundamental research before they could be broadly applied. This paper focuses on the results obtained in experiments with locally heated shear-driven Liquid Films in a flat mini-channel. A detailed map of the flow sub-regimes in a shear-driven Liquid film flow of water and FC-72 have been obtained for a 2 mm channel operating at room temperature. While the water film can be smooth under certain Liquid/gas flow rates, the surface of an intensively evaporating film of FC-72 is always distorted by a pattern of waves and structures. It was found, that when heated the shear-driven Liquid Films are less likely to rupture than gravity-driven Liquid Films. For shear-driven water Films the critical heat flux was found of up to 10 times higher than that for a falling film, which makes shear-driven Films (annular or stratified two-phase flows) more suitable for cooling applications than falling Liquid Films.
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interfacial thermal fluid phenomena in thin Liquid Films
International Journal of Emerging Multidisciplinary Fluid Sciences, 2010Co-Authors: Oleg KabovAbstract:Films are ubiquitous in nature and play an important role in our daily life. The paper focuses on the recent progress that has been achieved in the interfacial thermal fluid phenomena in thin Liquid Films and rivulets through conducting experiments and theory. Phase shift schlieren technique, fluorescence method and infrared thermography have been used. A spanwise regular structures formation was discovered for Films falling down an inclined plate with a built-in local rectangular heater. If the heating is low enough, a stable 2D flow with a bump at the front edge of the heater is observed. For lager heat flux this primary flow becomes unstable, and the instability leads to another steady 3D flow, which looks like a regular structure with a periodically bent leading bump and an array of longitudinal rolls or rivulets descending from it downstream. The heat flux needed for the onset of instability grows almost linearly with the increase of Re number. Strong surface temperature gradients up to 10–15 K/mm, both in the streamwise and spanwise directions have been measured. For a wavy film it was found that heating may increase the wave amplitude because thermocapillary forces are directed from the valley to the crest of the wave. Thin and very thin (less than 10 μm) Liquid Films driven by a forced gas/vapor flow (stratified or annular flows), i.e. shear-driven Liquid Films in a narrow channel are a promising candidate for the thermal management of advanced semiconductor devices in earth and space applications. Development of such technology requires significant advances in fundamental research, since the stability of joint flow of locally heated Liquid film and gas is a rather complex problem. Experiments with water and FC-72 in flat channels (height 0.2–2 mm) have been conducted. Maps of flow regimes were plotted. It was found that stratified flow exists and stable in the channels with 0.2 mm height and 40 mm width. The critical heat flux for a shear driven film may be up to 10 times higher than that for a falling Liquid film, and reaches 400 W/cm2 in experiments with water at atmospheric pressure. Some experiments have been done during parabolic flight campaigns of the European Space Agency under microgravity conditions. It was found that decreasing of gravity leads to a flow destabilization.Copyright © 2010 by ASME
Pulak Dutta - One of the best experts on this subject based on the ideXlab platform.
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molecular ordering in thin Liquid Films of polydimethylsiloxanes
Langmuir, 2001Co-Authors: Guennadi Evmenenko, S W Dugan, J Kmetko, Pulak DuttaAbstract:X-ray reflectivity has been used for investigations of molecular ordering in thin Liquid Films of polydimethylsiloxanes (PDMS) of low molecular weights deposited on a polished silicon wafer. The Liquid Films we studied were ∼40−90 A thick. Evidence of molecular layering induced by geometrical confinement by a hard wall is obtained for thin Films of lowest molecular weight PDMS. The positions of the secondary maxima in the Patterson functions, P(z), for these samples reveal a periodicity of about 10 A, consistent with the size of PDMS molecules. Further increasing the molecular weight leads to suppression of P(z) oscillations, causing the electron density profile to become more uniform. For higher molecular weight PDMS, a flatlike conformation of molecules absorbed on a solid surface is observed.
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observation of molecular layering in thin Liquid Films using x ray reflectivity
Physical Review Letters, 1999Co-Authors: A G Richter, Alokmay Datta, M K Durbin, Pulak DuttaAbstract:We report the direct observation of internal layering in thin ( $\ensuremath{\sim}45--90\AA{}$) Liquid Films of nearly spherical, nonpolar molecules, tetrakis(2-ethylhexoxy)silane, using synchrotron x-ray reflectivity. The Patterson functions have secondary maxima indicating layer formation, and model-independent fitting to the reflectivity data shows that there are three electron density oscillations near the solid-Liquid interface, with a period of $\ensuremath{\sim}10\AA{}$ (consistent with the molecular dimensions). The oscillation amplitude has a strong inverse dependence on the substrate surface roughness.
David R Clarke - One of the best experts on this subject based on the ideXlab platform.
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pattern formation in plastic Liquid Films on elastomers by ratcheting
Soft Matter, 2016Co-Authors: Jiangshui Huang, Jiawei Yang, David R ClarkeAbstract:Plastic Liquids, also known as Bingham Liquids, retain their shape when loads are small, but flow when loads exceed a threshold. We discovered that plastic Liquid Films coated on elastomers develop wavy patterns under cyclic loads. As the number of cycles increases, the wavelength of the patterns remains unchanged, but the amplitude of the patterns increases and then saturates. Because the patterns develop progressively under cyclic loads, we call this phenomenon as “patterning by ratcheting”. We observe the phenomenon in plastic Liquids of several kinds, and studied the effects of thickness, the cyclic frequency of the stretch, and the range of the stretch. Finite element simulations show that the ratcheting phenomenon can occur in materials described by a commonly used model of elastic–plastic deformation.
Jiawei Yang - One of the best experts on this subject based on the ideXlab platform.
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pattern formation in plastic Liquid Films on elastomers by ratcheting
Soft Matter, 2016Co-Authors: Jiangshui Huang, Jiawei Yang, David R ClarkeAbstract:Plastic Liquids, also known as Bingham Liquids, retain their shape when loads are small, but flow when loads exceed a threshold. We discovered that plastic Liquid Films coated on elastomers develop wavy patterns under cyclic loads. As the number of cycles increases, the wavelength of the patterns remains unchanged, but the amplitude of the patterns increases and then saturates. Because the patterns develop progressively under cyclic loads, we call this phenomenon as “patterning by ratcheting”. We observe the phenomenon in plastic Liquids of several kinds, and studied the effects of thickness, the cyclic frequency of the stretch, and the range of the stretch. Finite element simulations show that the ratcheting phenomenon can occur in materials described by a commonly used model of elastic–plastic deformation.
