Chip-on-mud: Ultra-low power ARM-based oceanic sensing system powered by small-scale benthic microbial fuel cells

An ARM-based sensing platform powered entirely by small-scale benthic microbial fuel cells (MFCs) for oceanic sensing applications is presented. The ultra-low power chip featuring an ARM Cortex-M0 processor, 3kB of SRAM, and power management unit (PMU) with energy harvesting from MFCs is designed to consume 11nW in sleep mode for perpetual sensing operation. A small-scale micro-MFC with 21.3cm² anode surface area was connected to the on-chip PMU to charge a thin film battery of 1mAh capacity. A 49.3-hour long-term experiment with 8-min sleep interval and 1 sec wake-up time demonstrated the sustainability of chip-on-mud concept. During sleep mode, the system charges the 4V battery at 380nA from the micro-MFC generating 5.4μW of power, which can support up to 20mA of active mode current.