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Snap-through in Graphene Nanochannels: With Application to Fluidic Control

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posted on 23.12.2020, 13:04 by Shuping Jiao, Mingchao Liu
Recent studies on the structure and transport behaviors of water confined within lamellar graphene have attracted intense interest in filtration technology, but the mechanism of water transport in complex membrane nanostructures remains an open question. For example, similar systems but at much larger scales have indicated that the instabilities of an elastic structure, such as snap-through, play an essential role in controlling the fluid flow. Graphene sheets, which have an atomic thickness, often appear highly wrinkled in nanofluidic devices and so are vulnerable to elastic instabilities. However, it remains unclear how does the flexible wrinkled structure affect the transport of water and filtration efficiency or whether such an effect can be exploited in devices. In this work, we explore the flow-induced snap-through in graphene nanochannels by combining molecular simulations with the theoretical analysis. We further demonstrate its applications to passive control of fluid flow and to ion/molecule selection. By introducing a flexible arch embedded within a graphene nanochannel, we observe the “snap” of the arched graphene wall from one stable state to another by varying the fluid flux (i.e., velocity); the critical velocity of this snap transition is found to depend nonmonotonically on the geometric size of the channel and the arch. We also demonstrate reversible snap-through by fixing the end parts of the flexible arch. These results suggest the potential of flow-induced snap-through in graphene-based nanochannels for ion/molecule selection applications in, for example, the design of a foul-resistant, easy-to-clean, reusable filter membrane.