'Ingestible Core-Body Thermometer' Operated by Harvested and Stored Energy via Gastric Acid Battery～Feasibility Study of Small Size Packaging Method and System

摘要

In this study, we have developed a tablet-shaped ingestible core-body temperature sensor based on gastric acid power generation for daily health care. A custom integrated circuit (IC), which had voltage boosting, bit-rate conversion, coding, modulating, and transmitting functions, was prototyped for the feasibility study of this system. A battery with a pair of Mg and Au electrodes generated approximately 1.2 V of output voltage in an artificial gastric juice. Moreover, it boosted the generated voltages to more than 3.5 V by the custom IC, and demonstrated the charging of a multilayer ceramic capacitor (MLCC) at the boosted voltage. Finally, we prototyped a tablet-shaped device and demonstrated that the temperature data measured by the device in pork was transferred to a loop antenna as a receiver at a distance of more than 20 cm via magnetic-field coupling telecommunication. This achievement paves the way to realizing a safe and ingestible core-body thermometer for daily use.