Influence of Electrolyte Composition on Liquid-Gated Carbon Nanotube and Graphene Transistors
Influence of Electrolyte Composition on Liquid-Gated Carbon Nanotube and Graphene Transistors
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DOI：
10.1021/ja104850n
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发表时间：
2010-12-08
影响因子：
15
通讯作者：
Lemay, Serge G.
中科院分区：
文献类型：
--
作者：
Heller, Iddo;Chatoor, Sohail;Lemay, Serge G.
基于单壁碳纳米管 (SWNT) 和石墨烯的场效应晶体管可以在溶液中充当高灵敏度纳米级（生物）传感器。在这里，我们通过实验比较了单壁碳纳米管和石墨烯晶体管如何响应它们所浸入的水性电解质的成分变化。我们表明，单壁碳纳米管和石墨烯的电导受到离子强度、pH 值和存在离子类型变化的强烈影响，其影响方式对于石墨烯和单壁碳纳米管器件来说可能有本质上的不同。我们证明，这种对电解质成分的敏感性是由不同机制的组合造成的，包括静电门控、肖特基势垒修改和栅极电容的变化。有趣的是，我们发现强有力的证据表明传感器对电解质成分变化的响应受到底层基板和碳表面上高密度可电离基团的影响。我们提出了一个基于与这些可电离基团相关的（调节的）表面电荷的模型，该模型解释了我们的大部分数据。我们的发现对于解释和优化纳米碳晶体管的传感实验具有重要意义。对于细胞提取物、生长培养基或体液等复杂的生物样品尤其如此，需要考虑溶液的完整成分。
Field-effect transistors based on single-walled carbon nanotubes (SWNTs) and graphene can function as highly sensitive nanoscale (bio)sensors in solution. Here, we compare experimentally how SWNT and graphene transistors respond to changes in the composition of the aqueous electrolyte in which they are immersed. We show that the conductance of SWNTs and graphene is strongly affected by changes in the ionic strength, the pH, and the type of ions present, in a manner that can be qualitatively different for graphene and SWNT devices. We show that this sensitivity to electrolyte composition results from a combination of different mechanisms including electrostatic gating, Schottky-barrier modifications, and changes in gate capacitance. Interestingly, we find strong evidence that the sensor response to changes in electrolyte composition is affected by a high density of ionizable groups on both the underlying substrate and the carbon surfaces. We present a model based on the (regulated) surface charge associated with these ionizable groups that explains the majority of our data. Our findings have significant implications for interpreting and optimizing sensing experiments with nanocarbon transistors. This is particularly true for complex biological samples such as cell extracts, growth media, or bodily fluids, for which the complete composition of the solution needs to be considered.