In-situ environmental monitoring by a real self-driven microbial fuel cell-based sensor including data acquisition system

Self-driven monitoring technique is specifically requested in remote areas. Microbial fuel cell (MFC) was a galvanic cell that has been applied for various environment monitoring. However, MFC is a self-driven probe rather than sensor, since external power was needed for data acquisition. Here, a real self-driven MFC based sensor was developed by using a simplified energy management system (EMS) to enable MFC to power data logger. In this simplified EMS, some common electronics of capacitor, voltage comparator, resistance and trigger switches were removed to reduce power dissipation. As a result, the logger was powered without longtime energy harvesting from MFC. Moreover, since the MFC current generation is changeable with the sampling signal, a rechargeable battery was added as backup power when the current from MFC was too low, or as an energy storage for surplus energy collection other times. Take a dissolved oxygen (DO) sensor as an application example, a MFC was able to detect DO (with a very short energy harvesting time of 10 s), and power logger (with a 1.6% deviation to that with an AC powered Keithley logger), and charge backup battery at the same time, when DO > 5.3 mg/L. When DO < 0.8 mg/L, the power generated from MFC was too low to drive the EMS, and logger was only powered by the rechargeable battery. Besides DO monitoring, this self-driven system may work for other types of MFC sensor as well, such as toxicant sensor, biochemical oxygen demand (BOD) sensor and so on. With a 38$ cost, this self-driven MFC sensor was competitive and attractive for in-situ environment survey.