Śmietana Mateusz, Janaszek Bartosz, Lechowicz Katarzyna, Sezemsky Petr, Koba Marcin, Burnat Dariusz, Kieliszczyk Marcin, Stranak Vitezslav, Szczepański Paweł
Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw, Poland.
University of South Bohemia, Branisovska 31, 37005 Ceske Budejovice, Czech Republic.
Nanophotonics. 2021 Dec 15;11(3):593-602. doi: 10.1515/nanoph-2021-0687. eCollection 2022 Jan.
Sensitivity, selectivity, reliability, and measurement range of a sensor are vital parameters for its wide applications. Fast growing number of various detection systems seems to justify worldwide efforts to enhance one or some of the parameters. Therefore, as one of the possible solutions, multi-domain sensing schemes have been proposed. This means that the sensor is interrogated simultaneously in, e.g., optical and electrochemical domains. An opportunity to combine the domains within a single sensor is given by optically transparent and electrochemically active transparent conductive oxides (TCOs), such as indium tin oxide (ITO). This work aims to bring understanding of electro-optically modulated lossy-mode resonance (LMR) effect observed for ITO-coated optical fiber sensors. Experimental research supported by numerical modeling allowed for identification of the film properties responsible for performance in both domains, as well as interactions between them. It has been found that charge carrier density in the semiconducting ITO determines the efficiency of the electrochemical processes and the LMR properties. The carrier density boosts electrochemical activity but reduces capability of electro-optical modulation of the LMR. It has also been shown that the carrier density can be tuned by pressure during magnetron sputtering of ITO target. Thus, the pressure can be chosen as a parameter for optimization of electro-optical modulation of the LMR, as well as optical and electrochemical responses of the device, especially when it comes to label-free sensing and biosensing.
传感器的灵敏度、选择性、可靠性和测量范围是其广泛应用的关键参数。各种检测系统数量的快速增长似乎证明了全球范围内为提高其中一个或某些参数所做的努力是合理的。因此，作为一种可能的解决方案，人们提出了多域传感方案。这意味着例如在光学和电化学领域同时对传感器进行询问。光学透明且具有电化学活性的透明导电氧化物（TCO），如氧化铟锡（ITO），为在单个传感器内结合这些领域提供了机会。这项工作旨在深入了解在涂有ITO的光纤传感器中观察到的电光调制损耗模式共振（LMR）效应。通过数值模拟支持的实验研究能够确定在两个领域中决定性能的薄膜特性以及它们之间的相互作用。已经发现，半导体ITO中的电荷载流子密度决定了电化学过程的效率和LMR特性。载流子密度提高了电化学活性，但降低了LMR的电光调制能力。还表明，在ITO靶磁控溅射过程中，载流子密度可以通过压力进行调节。因此，可以选择压力作为优化LMR的电光调制以及器件的光学和电化学响应的参数，特别是在无标记传感和生物传感方面。
