Electric double layer (EDL), the organized distribution of ions and electrons at the solid–liquid interface, is a ubiquitous phenomenon in electrochemical, supercapacitor and field-effect transistor applications. With the development of some new types of supercapacitors and transistors, the detection of EDL lateral distribution at the heterogeneous interface attracts increasing attention. In this paper, we propose a surface plasmon resonance (SPR) imaging method for the lateral EDL distribution detection over millimeter-scale field of vision. We established a model for the first time to describe the relationship between SPR responses and EDL structural changes with ions effective volume fraction, concentration and dielectric constant for different solution. This model converts EDL structure at each position on the interface into SPR images by weighted averaging of ions concentration distribution perpendicular to the interface. Thus, different EDL structures will produce different SPR responses, and the lateral variations of EDL structures across the heterogeneous interface could be mapped by SPR imaging. Furthermore, via continuous imaging, the change dynamics of EDL could be obtained. According to the simulation results, we performed experiments under different potential stimulations with solutions of different ion concentrations and ionic species. The experimental results demonstrated that our method can monitor the EDL change dynamics in real time and map the lateral EDL distribution at the heterogeneous electrode/electrolyte interface. The SPR method can help to improve the understanding of EDL carriers’ transport and mobility across the heterogeneous interface, which is crucial for applications in novel transistors and bioanalytical devices.

中文翻译：

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异质双电层分布的表面等离子体共振成像及其变化动力学

双电层（EDL）是离子和电子在固液界面的有组织分布，是电化学，超级电容器和场效应晶体管应用中普遍存在的现象。随着一些新型超级电容器和晶体管的发展，异质界面上EDL横向分布的检测引起了越来越多的关注。在本文中，我们提出了一种表面等离子体共振（SPR）成像方法，用于在毫米级视场上进行横向EDL分布检测。我们首次建立了一个模型来描述不同溶液中离子的有效体积分数，浓度和介电常数对SPR响应和EDL结构变化之间的关系。该模型通过垂直于界面的离子浓度分布的加权平均，将界面上每个位置的EDL结构转换为SPR图像。因此，不同的EDL结构将产生不同的SPR响应，并且可以通过SPR成像映射跨异类接口的EDL结构的横向变化。此外，通过连续成像，可以获得EDL的变化动态。根据模拟结果，我们在不同的潜在刺激下使用不同的离子浓度和离子种类的溶液进行了实验。实验结果表明，我们的方法可以实时监测EDL变化动态，并绘制异质电极/电解质界面上的横向EDL分布图。SPR方法有助于提高对EDL载流子跨异质界面传输和迁移率的理解，这对于在新型晶体管和生物分析设备中的应用至关重要。