A water‐induced electromechanical response in suspended graphene atop a microfluidic channel is reported. The graphene membrane resistivity rapidly decreases to ≈25% upon water injection into the channel, defining a sensitive “channel wetting” device—a wetristor. The physical mechanism of the wetristor operation is investigated using two graphene membrane geometries, either uncovered or covered by an inert and rigid lid (hexagonal boron nitride multilayer or poly(methyl methacrylate) film). The wetristor effect, namely the water‐induced resistivity collapse, occurs in uncovered devices only. Atomic force microscopy and Raman spectroscopy indicate substantial morphology changes of graphene membranes in such devices, while covered membranes suffer no changes, upon channel water filling. The results suggest an electromechanical nature for the wetristor effect, where the resistivity reduction is caused by unwrinkling of the graphene membrane through channel filling, with an eventual direct doping caused by water being of much smaller magnitude, if any. The wetristor device should find useful sensing applications in general micro‐ and nanofluidics.

中文翻译：

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石墨烯机电水传感器：Wetristor

据报道，在微流体通道顶部的悬浮石墨烯中，水诱导了机电响应。将水注入通道后，石墨烯膜的电阻率迅速降低至≈25％，这定义了一个灵敏的“通道润湿”装置-湿敏电阻。使用两种石墨烯膜几何结构研究了湿敏电阻运行的物理机理，这两种石墨烯膜没有被惰性的刚性盖（六方氮化硼多层膜或聚（甲基丙烯酸甲酯）膜覆盖）覆盖或覆盖。湿敏电阻效应，即水致电阻率崩溃，仅在未覆盖的设备中发生。原子力显微镜和拉曼光谱表明，在此类装置中，石墨烯膜的形态发生了实质性变化，而被覆盖的膜在通道注水后未发生任何变化。结果表明了湿敏电阻效应的机电性质，其中电阻率降低是由石墨烯膜通过通道填充引起的皱纹引起的，最终由水引起的直接掺杂的程度要小得多（如果有的话）。湿敏电阻器件应在一般的微流体和纳米流体中找到有用的传感应用。