Integration of in-situ chemical sensors and ocean observation platforms

In recent years, the development of the autonomous ocean observation platforms such as autonomous underwater vehicle (AUV) and ocean glider is remarkable, and the deployment of wide area/long term to the ocean is pushed forward. The chemical sensor which can measure an objective component directly is the most suitable tool to obtain temporally and spatially consecutive data without needing reagents. Furthermore, because the downsizing of the electronic circuit board and the electrode is relatively easy for the chemical sensor, the deployment to the oceanographic observation platform of small payload is possible.

I developed in-situ chemical sensor to perform field measurement of pH, pCO2 and oxidation-reduction potential (ORP) in the ocean with high accuracy, and the field observations in the various kinds of ocean including the deep sea were performed using the sensor. The present downsized electronic circuit board is multichannel and digital (RS232C, RS485, RS422)/analog (1-5V) output. The RS232C connection is used for large AUV, and large ROV and ocean glider, and the RS485 connection is used for small ROV, and the RS422 connection uses long distance RS422 cable, and the analog connection is used for CTD-RMS. In addition, standalone installation of the sensor is used for small AUV. The ocean observation platform (ROV, CTD-RMS and RS422) is connected to with a cable is possible to real-time monitoring on board (or on land).

The small multisensor integration control system that can control the developed sensor and the commercial sensor has been developing. Nine kinds of sensors (pH, pCO2, ORPl, depth, salinity, water temperature, dissolved O2 (DO), turbidity and the fluorescence organic compound) were integrated at present. An application to long-term observation and the deployment to the platform of this system are pushed forward.