Marine monitoring by organic electrochemical transistors

Understanding the influence of environmental changes on marine life is important to ecological sustainability and aqua-culture. Existing sensors are limited by size and costs that preclude widespread non-intrusive monitoring. This work reports on various organic electrochemical transistors (OECTs) to track dissolved oxygen concentration and nutrient runoff in seawater, a highly challenging matrix owing to its high ionic strength and multitude of chemical interferents. We present the dual-gate configuration that extended the device stability window by preventing undesirable reactions at the OECT channel. Specifically, the sensor achieved a detection limit of 0.5 ppm dissolved oxygen concentration in seawater. We engineer a system to monitor the correlation of oyster movement with dissolved oxygen in its environment, and it offers a new design to realize compact, highly sensitive, economical in-situ sensors for harsh marine environments.