Electrical Probing of Submicroliter Liquid Using Graphene Strip Transistors Built on a Nanopipette
Electrical Probing of Submicroliter Liquid Using Graphene Strip Transistors Built on a Nanopipette
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DOI：
10.1002/smll.201101859
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发表时间：
2012-01-09
期刊：
影响因子：
13.3
通讯作者：
Li, Lain-Jong
中科院分区：
文献类型：
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作者：
Chen, Chang-Hsiao;Lin, Cheng-Te;Li, Lain-Jong
单壁碳纳米管（SWNT）和石墨烯薄膜具有高度生物相容性，最近在电子和传感应用中引起了极大的关注。例如，基于SWNT的场效应晶体管（FET）器件已成功用于执行各种分析物的电检测，例如有毒气体，[1-3]蛋白质，[4-6] DNA，[7-10]和生物分子。[11-13]石墨烯或氧化石墨烯片也已被证明可用作FET中的传感组件。[14-16]然而，由于所制造的晶体管器件的横向尺寸大，检测通常需要大量的分析物溶液。由于像膜片钳这样的纳米级探针已被广泛用于检测来自局部环境的信号，例如细胞内或细胞间隙，[17-19]越来越多的努力致力于开发用于空间局部检测的纳米级或探针型FET。[20在本文中，我们证明了化学气相沉积的石墨烯片可以转移到玻璃纳米移液管上以形成石墨烯条，其可以在探针端连接以形成晶体管沟道。这种石墨烯基晶体管可以在液体门控条件下工作，从而允许对亚微升体积的液滴的pH值进行电检测。硼硅酸盐型玻璃毛细管，内径为0. 86 mm，外径为1. 5 mm，长度为75 mm（哈佛仪器，Holliston，MA，USA）中的每一个，用微量移液器拉出器拉出并热抛光。（P-97，Sutter Instrument）加入吸头直径从几百纳米到几十微米的移液管中，这取决于拉取参数。石墨烯单层通过化学气相沉积（CVD）在Cu上生长，如先前由其他组报道的。[22-24]用聚（甲基丙烯酸甲酯）（PMMA）层旋涂Cu上生长的石墨烯。
Single-walled carbon nanotubes (SWNTs) and graphene films are highly biocompatible and have recently attracted a great deal of attention for electronic and sensing applications. For example, SWNT-based field-effect transistor (FET) devices have been successfully used to perform electrical detection of various analytes, such as toxic gases,[1–3] proteins,[4–6] DNA,[7–10] and biomolecules.[11–13] Graphene or graphene oxide sheets have also been demonstrated to function as sensing components in FETs.[14–16] However, the detection normally requires a significant quantity of analyte solution due to the fact that the lateral size of the fabricated transistor devices is large. Since nanoscale probes like patch clamps have been widely used to detect the signals from a localized environment, such as inside a cell or intercellular space,[17–19] more and more efforts have been devoted to developing nanoscale or probe-type FETs for space-localized detection.[20, 21] Herein, we demonstrate that chemical-vapor-deposited graphene sheets can be transferred onto a glass nanopipette to form graphene strips, which can be connected at the probe end to form a transistor channel. This graphene-based transistor can be operated in a liquid-gating condition, thereby allowing the electrical detection of the pH value for a droplet with submicroliter volume.Borosilicate-type glass capillaries with an inner diameter of 0.86 mm, outer diameter of 1.5 mm, and length 75 mm (Harvard Apparatus, Holliston, MA, USA) were pulled and heat-polished with a micropipette puller (P-97, Sutter Instrument) into pipettes with tip diameters from hundreds of nanometers to tens of micrometers depending on the pulling parameters. Graphene monolayers were grown on Cu by chemical vapor deposition (CVD) as reported earlier by other groups.[22–24] As-grown graphene on Cu was spincoated with a layer of poly (methyl methacrylate)(PMMA).