An Integrated Microfluidic System for Manganese Anomaly Detection Based on Chemiluminescence: Description and Practical Use to Discover Hydrothermal Plumes Near the Okinawa Trough

• Published in: IEEE journal of oceanic engineering 2013-01, Vol.38 (1), p.178-185
• Main Authors: Provin, C., Fukuba, T., Okamura, K., Fujii, T.
• Format: Article
• Language: English
• Subjects: Chemical analysis; Coils; luminescence; Manganese; manganese (Mn); microfluidics; microvalves; Oceans; Quantum well devices; Regulators; Valves
• ISSN: 0364-9059; 1558-1691
• DOI: 10.1109/JOE.2012.2208849

Underwater hydrothermal vents draw a lot of interest as they are the shelter for unique ecosystems, besides being a possible new opportunity for ore mining. Manganese (Mn) is found at a high concentration in hydrothermal vents, which make it possible to use this metal ion as a tracer to detect and evaluate new hydrothermal sources. Here we present a miniaturized and integrated microfluidic system for the detection of Mn in deep-sea environment, called the integrated in situ analyzer for Mn 2+ (IISA-Mn). The detection system is based on the chemiluminescence reaction of Mn contained in the seawater sample with a luminol-based reagent, which offers a high sensitivity. This system is composed of a microdevice for mixing and reaction, a pumping unit, several valving units, and a photomultiplier (PMT) detector. The system is able to detect Mn concentration above 280 nM in seawater, and gives a quite linear response until 500 nM. It is also proven to be able to work continuously during the 8 h of an actual remotely operated vehicle (ROV) dive. This system has led to the discovery of a previously unknown hydrothermal site in the Okinawa Trough.