Voltage Detector Integrated Circuit as Versatile Toolbox for Charge Management of Thermally Chargeable Supercapacitor

Abstract Internet of Things (IoT) is crucial for a sustainable society from the viewpoints of optimization of energy consumption and using timing, thus aiding reduced CO₂ emissions. Traditional power supply methods such as batteries are impractical for driving the trillions of sensors that future systems will likely utilize for collecting extensive environmental information. Thermoelectric power generators that enable direct heat‐to‐electricity energy conversion are considered a promising power supplying technology without maintenance because thermal energy is a ubiquitous energy source. This study develops a new class of thermoelectric modules using redox‐free electrolytes—‐thermally chargeable supercapacitor (TCS)—‐with extremely high thermoelectromotive force, generating over 2 V from a temperature difference of ≈65 °C without requiring a DC‐to‐DC converter. Additionally, using a voltage detector is demonstrated to be a versatile and efficient toolbox for the charge management of TCS. Optimization of the circuit comprising the TCS module with the ultrahigh open‐circuit voltage and voltage detector enables the automatic charging of a large capacitor, which intermittently powers different devices such as a beacon, LED, piezo speaker, and motor with the desired frequency. This approach represents a significant step toward sustainable energy in the context of low‐grade thermal energy harvesting and optimized energy consumption through IoT.