The surface diffusion (dissipation) of charge carriers enhanced by water molecules in solution-based biosensors and ambient operating gas sensors strongly influence their resistance response, sensitivity, and stability in time. Therefore, the information on the charge distribution at interfaces of conductive and insulating parts is essential for the operating sensors. This work presents the simultaneous measurement of the longitudinal macroscopic resistance response and local surface potential (SP) mapping by Kelvin probe force microscopy (KPFM) on a graphene Hall bar sensor. The results show the propagation of an electric charge from the main graphene channel onto the neighboring SiO₂ surface. The charge propagation strongly increases with the relative humidity and can be controlled by a bottom-gate voltage used in most sensors based on a field effect transistor (FET) architecture. As proved by the longitudinal resistance measurements, the resulting side charge accumulation has a very small impact on the 2D resistivity of the graphene channel. It has been explained by an application of the Thomas-Fermi theory, proving an efficient screening of side accumulated charge potential caused by a redistribution of the charge inside the wide graphene channel. The combination of a transport resistance response and KPFM provides a deeper understanding of sensors/biosensors functionality and their design features than a simple resistance response usually observed.

在基于溶液的生物传感器和环境操作气体传感器中，水分子增强的电荷载体的表面扩散（耗散）强烈影响它们的电阻响应、灵敏度和时间稳定性。因此，导电部件和绝缘部件界面处的电荷分布信息对于传感器的运行至关重要。这项工作提出了通过开尔文探针力显微镜 (KPFM) 在石墨烯霍尔棒传感器上同时测量纵向宏观电阻响应和局部表面电势 (SP) 映射。结果显示电荷从主石墨烯通道传播到邻近的 SiO ₂表面。电荷传播随着相对湿度的增加而急剧增加，并且可以通过大多数基于场效应晶体管 (FET) 架构的传感器中使用的底栅电压来控制。纵向电阻测量证明，所产生的侧向电荷积累对石墨烯沟道的二维电阻率影响非常小。托马斯-费米理论的应用对此进行了解释，证明了对宽石墨烯通道内电荷重新分布引起的侧积累电荷电势的有效屏蔽。与通常观察到的简单电阻响应相比，传输电阻响应和 KPFM 的结合可以更深入地了解传感器/生物传感器的功能及其设计特征。