Development of a sediment microbial fuel cell-based biosensor for simultaneous online monitoring of dissolved oxygen concentrations along various depths in lake water Na Song a , Zaisheng Yan a , Huacheng Xu a , Zongbao Yao a , Changhui Wang a , Mo Chen b , Zhiwei Zhao c , Zhaoliang Peng a , Chunliu Wang a , He-Long Jiang a, ⁎ a State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China b Faculty of Resources and Environmental Science, Hubei University, Wuhan 430062, China c School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China HIGHLIGHTS • A novel sediment microbial fuel cell- based biosensor was developed. • The sensor could online monitor the DO in different depths of lake water. • The optimal anode to single cathode area ratio was 11:1. • Organic matter contents in sediment af- fect the sensor operation performance. • The sensor could be used as an early- alert program in a shallow lake. GRAPHICAL ABSTRACT abstract article info Article history: Received 2 January 2019 Received in revised form 2 April 2019 Accepted 2 April 2019 Available online 03 April 2019 Editor: Zhen (Jason) He A novel multi-cathode, single-anode system integrating a sediment microbial fuel cell -based biosensor was de- veloped for in-situ, continuous, and online monitoring of dissolved oxygen (DO) concentrations along various depths of lake water. The signal feedback mechanism was evaluated based on a relationship between voltage and DO concentration at corresponding depths. With an external resistance of 1000 Ω, a linear relationship was found (regression coefficient, R 2 = 0.9576) between voltage and DO in the range of 0–9 mg L -1 . The sensor performance was further optimized under various influence factors. The results of indoor experiments indicated that the optimal anode to single cathode area ratio was 11:1. The sensor signal could also be significantly influenced by organic matter content in sediment; thus, the addition of 5% organic matter could obtain a stable anode potential and a high voltage output. Furthermore, the sensor was operated in-situ for 67 days in a lake en- vironment, which also led to a good correlation between the voltage and DO (R 2 = 0.8897). Thus, this integrated system has great potential as an early-warning program to help identify environmental risks in aquatic environments. © 2019 Elsevier B.V. All rights reserved. Keywords: Sediment microbial fuel cell Multi-cathode Dissolved oxygen Biosensor Aquatic environment Science of the Total Environment 673 (2019) 272–280 ⁎ Corresponding author at: Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China. E-mail address: hljiang@niglas.ac.cn (H.-L. Jiang). https://doi.org/10.1016/j.scitotenv.2019.04.032 0048-9697/© 2019 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv