Janik Monika, Lechowicz Katarzyna, Pituła Emil, Warszewski Jakub, Koba Marcin, Śmietana Mateusz
Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662, Warsaw, Poland.
National Institute of Telecommunications, Szachowa 1, 02-894, Warsaw, Poland.
Sci Rep. 2023 Sep 19;13(1):15523. doi: 10.1038/s41598-023-42853-0.
Spectroelectrochemical (SEC) measurements play a crucial role in analytical chemistry, utilizing transparent or semitransparent electrodes for optical analysis of electrochemical (EC) processes. The EC readout provides information about the electrode's state, while changes in the transmitted optical spectrum help identify the products of EC reactions. To enhance SEC measurements, this study proposes the addition of optical monitoring of the electrode. The setup involves using a polymer-clad silica multimode fiber core coated with indium tin oxide (ITO), which serves as both the electrode and an optical fiber sensor. The ITO film is specifically tailored to exhibit the lossy-mode resonance (LMR) phenomenon, allowing for simultaneous optical monitoring alongside EC readouts. The LMR response depends on the properties of the ITO and the surrounding medium's optical properties. As a result, the setup offers three types of interrogation readouts: EC measurements, optical spectrum analysis corresponding to the volume of the analyte (similar to standard SEC), and LMR spectrum analysis reflecting the state of the sensor/electrode surface. In each interrogation path, cyclic voltammetry (CV) experiments were conducted individually with two oxidation-reduction reaction (redox) probes: potassium ferricyanide and methylene blue. Subsequently, simultaneous measurements were performed during chronoamperometry (CA) with the sensor, and the cross-correlation between the readouts was examined. Overall, this study presents a novel and enhanced SEC measurement approach that incorporates optical monitoring of the electrode. It provides a comprehensive understanding of EC processes and enables greater insights into the characteristics of the analyte.
光谱电化学（SEC）测量在分析化学中起着至关重要的作用，它利用透明或半透明电极对电化学（EC）过程进行光学分析。EC读数提供有关电极状态的信息，而透射光谱的变化有助于识别EC反应的产物。为了增强SEC测量，本研究提出增加对电极的光学监测。该装置涉及使用涂有氧化铟锡（ITO）的聚合物包覆二氧化硅多模光纤芯，它既作为电极又作为光纤传感器。ITO薄膜经过特殊设计以呈现损耗模式共振（LMR）现象，从而能够在进行EC读数的同时进行光学监测。LMR响应取决于ITO的特性以及周围介质的光学特性。因此，该装置提供三种类型的询问读数：EC测量、与分析物体积相对应的光谱分析（类似于标准SEC）以及反映传感器/电极表面状态的LMR光谱分析。在每个询问路径中，分别使用两种氧化还原反应（redox）探针——铁氰化钾和亚甲基蓝进行循环伏安法（CV）实验。随后，在使用传感器进行计时电流法（CA）期间进行同步测量，并检查读数之间的互相关性。总体而言，本研究提出了一种新颖且增强的SEC测量方法，该方法纳入了对电极的光学监测。它提供了对EC过程的全面理解，并能够更深入地洞察分析物的特性。
