Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hong Kong, China.
Nano Lett. 2012 Mar 14;12(3):1404-9. doi: 10.1021/nl2040805. Epub 2012 Feb 14.
Solution-gated graphene field effect transistors (SGGT) were integrated in microfluidic systems. The transfer characteristics of a SGGT with an Ag/AgCl gate electrode shifted horizontally with the change of the ionic concentration of KCl solution in the microchannel and the relationship can be fitted with the Nernst equation, which was attributed to the change of the potential drop at the Ag/AgCl electrode. Therefore the gate electrode is one important factor for the ion sensitive property of the SGGT. Then SGGTs were used as flow velocity sensors, which were based on measuring the streaming potentials in microfluidic channels. A linear relationship between the shift of the transfer curve of the SGGT and the flow velocity was obtained, indicating that the SGGT is a promising transducer for measuring flow velocity in a microchip. Since the streaming potential is influenced by the three physical quantities, including the flow velocity, the ionic strength of the fluid and the zeta potential of the substrate, the device can be used for sensing any one of the three quantities when the other two were known. It is noteworthy that SGGTs have been used for various types of chemical and biological sensors. Array of the devices integrated in multichannel microchips are expected to find many important applications in the lab-on-a-chip systems in the future.
溶液门控石墨烯场效应晶体管（SGGT）被集成到微流控系统中。带有 Ag/AgCl 栅电极的 SGGT 的传输特性随着微通道中 KCl 溶液离子浓度的变化而水平移动，这种关系可以用能斯特方程拟合，这归因于 Ag/AgCl 电极处的电势差的变化。因此，栅电极是 SGGT 离子敏感特性的一个重要因素。然后，SGGT 被用作流速传感器，其基于测量微流道中的流动电势。SGGT 的传输曲线的偏移与流速之间存在线性关系，表明 SGGT 是一种很有前途的用于测量微芯片中流速的换能器。由于流动电势受到三个物理量的影响，包括流速、流体的离子强度和基底的 zeta 电位，因此当已知其中两个量时，该器件可用于感测这三个量中的任意一个。值得注意的是，SGGT 已被用于各种类型的化学和生物传感器。集成在多通道微芯片中的器件阵列有望在未来的片上实验室系统中找到许多重要的应用。
