Slip length measurement in rectangular graphene nanochannels with a 3D flow analysis
Slip length measurement in rectangular graphene nanochannels with a 3D flow analysis
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DOI：
10.1016/j.carbon.2021.12.048
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发表时间：
2021-11
期刊：
影响因子：
10.9
通讯作者：
Kuan-Ting Chen;Qinyi Li;Takeshi Omori;Y. Yamaguchi;T. Ikuta;Koji Takahashi
中科院分区：
文献类型：
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作者：
Kuan-Ting Chen;Qinyi Li;Takeshi Omori;Y. Yamaguchi;T. Ikuta;Koji Takahashi
虽然已经对石墨烯上的滑移流进行了许多分子动力学模拟，但实验工作仍然非常有限，我们对石墨烯上的流动摩擦的理解仍然远远不够。在这里，为了准确地测量矩形纳米通道中的滑移长度，我们开发了一个三维毛细流动模型，该模型充分考虑了非均匀横截面速度分布、滑移边界条件和动态接触角。我们表明，三维分析是必要的，即使是一个通道的宽度/高度比为100。我们制作了深度为45 nm、宽度为5 μm的石墨烯纳米通道，并使用该三维流动模型测量了约30-40 nm的滑移长度。我们还重新评估了从文献中的毛细管填充实验获得的石墨烯的滑移长度数据：对于25 nm深的通道，30 nm而不是最初声称的45 nm，对于8.5 nm深的通道，47 nm而不是60 nm。我们发现一个较小的滑移长度比现有的实验测量，由于我们的方法中考虑了我们的全三维流动分析。这项工作提出了一个严格的分析方法，同时也提供了一个更好的理解滑流在石墨烯纳米通道，这将有利于进一步创新的纳米流体应用，包括电子冷却和生物医学芯片。
Although many molecular dynamics simulations have been conducted on slip flow on graphene, experimental efforts remain very limited and our understanding of the flow friction on graphene remains far from sufficient. Here, to accurately measure the slip length in rectangular nanochannels, we develop a 3D capillary flow model that fully considers the nonuniform cross-section velocity profile, slip boundary conditions, and the dynamic contact angle. We show that the 3D analysis is necessary even for a channel with a width/height ratio of 100. We fabricated graphene nanochannels with 45-nm depth and 5-μm width, and measured slip lengths of about 30–40 nm using this 3D flow model. We also reevaluated the slip-length data for graphene obtained from capillary filling experiments in the literature: 30 nm instead of originally claimed 45 nm for a 25-nm-deep channel, and 47 nm instead of 60 nm for an 8.5-nm-deep channel. We discover a smaller slip length than existing experimental measurements due to our full 3D flow analysis considered in our method. This work presents a rigorous analysis approach while also providing a better understanding of slip flow in graphene nanochannels, which will benefit further innovation in nanofluidic applications, including electronics cooling and biomedical chips.