Solar Panel Powered Coin-Cell Supercapacitor for Temperature Body Sensors

This paper proposes a body temperature monitoring system using a coin-cell supercapacitor. The system employs an infrared temperature sensor with a resolution of 0.02°C. The sensor has dimensions of 16.5×11.5×6 mm and requires a supply voltage of 3-5V and a current of 2.5mA. Three different types of supercapacitors were tested: a coin-type with dimensions of 11.5×12.5 mm, 0.22F, and 5.5V; another coin-type with dimensions of 19×6.5 mm, 1F, and 5.5V; and a cylindrical type with dimensions of 8×24 mm, 5F, and 2.8V. The 5.5V, 1F supercapacitor was chosen for the final system as it was deemed the most suitable for the required specifications and dimensions. The microcontroller is an Arduino Pro Mini, measuring 18×33×0.8 mm, operating at 3.3V with an 8MHz frequency. The solar panel (44×24×1 mm) charges the supercapacitors, providing a voltage of 5.5V and a current of 25mA under optimal conditions, ensuring continuous system operation. An intermittent LED was chosen to notify the user of temperature changes. An MCP1700 3V voltage regulator stabilized the supercapacitor voltage for optimal system performance. It was selected for its minimal dropout voltage of 0.178V.