Yin Jiawen, Gao Wanlei, Yu Weijian, Guan Yihua, Wang Zhenyu, Jin Qinghui
Faculty of Electrical Engineering and Computer Science, Ningbo University, 315211 Ningbo, P. R. China.
State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050 Shanghai, P. R. China.
Microsyst Nanoeng. 2022 Apr 8;8:39. doi: 10.1038/s41378-022-00359-1. eCollection 2022.
Free chlorine is one of the key water quality parameters in tap water. However, a free chlorine sensor with the characteristics of batch processing, durability, antibiofouling/antiorganic passivation and in situ monitoring of free chlorine in tap water continues to be a challenging issue. In this paper, a novel silicon-based electrochemical sensor for free chlorine that can self-clean and be mass produced via microfabrication technique/MEMS (Micro-Electro-Mechanical System) is proposed. A liquid-conjugated Ag/AgCl reference electrode is fabricated, and electrochemically stable BDD/Pt is employed as the working/counter electrode to verify the effectiveness of the as-fabricated sensor for free chlorine detection. The sensor demonstrates an acceptable limit of detection (0.056 mg/L) and desirable linearity ( = 0.998). Particularly, at a potential of +2.5 V, hydroxyl radicals are generated on the BBD electrode by electrolyzing water, which then remove the organic matter attached to the surface of the sensor though an electrochemical digestion process. The performance of the fouled sensor recovers from 50.2 to 94.1% compared with the initial state after self-cleaning for 30 min. In addition, by employing the MEMS technique, favorable response consistency and high reproducibility (RSD < 4.05%) are observed, offering the opportunity to mass produce the proposed sensor in the future. A desirable linear dependency between the pH, temperature, and flow rate and the detection of free chlorine is observed, ensuring the accuracy of the sensor with any hydrologic parameter. The interesting sensing and self-cleaning behavior of the as-proposed sensor indicate that this study of the mass production of free chlorine sensors by MEMS is successful in developing a competitive device for the online monitoring of free chlorine in tap water.
游离氯是自来水中关键的水质参数之一。然而，具备批量处理、耐用性、抗生物污染/抗有机钝化特性且能对自来水中的游离氯进行原位监测的游离氯传感器仍是一个具有挑战性的问题。本文提出了一种新型的基于硅的游离氯电化学传感器，该传感器可通过微加工技术/微机电系统（MEMS）进行自清洁并实现批量生产。制备了一种液接Ag/AgCl参比电极，并采用电化学稳定的BDD/Pt作为工作/对电极，以验证所制备传感器用于游离氯检测的有效性。该传感器具有可接受的检测限（0.056 mg/L）和良好的线性度（ = 0.998）。特别地，在 +2.5 V的电位下，通过电解水在BBD电极上产生羟基自由基，然后通过电化学消解过程去除附着在传感器表面的有机物。经过30分钟的自清洁后，被污染传感器的性能相对于初始状态从50.2%恢复到94.1%。此外，通过采用MEMS技术，观察到了良好的响应一致性和高重现性（RSD < 4.05%），为未来批量生产所提出的传感器提供了可能。观察到pH、温度和流速与游离氯检测之间存在理想的线性相关性，确保了该传感器在任何水文参数下的准确性。所提出传感器有趣的传感和自清洁行为表明，这项关于通过MEMS批量生产游离氯传感器的研究成功开发出了一种用于在线监测自来水中游离氯的有竞争力的设备。
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