Design and Experimental Validation of the Self-powered IoT for Indoor Temperature-Humidity Monitoring

The Internet of Things (IoT) refers to electronic device communications, one of them is the wireless sensor network (WSN). Battery life is the main challenge for WSN. Battery life refers to the maximum time until one node not work. This study proposed to increase the battery life of WSN by applying solar energy harvesting technology. The system consists of several nodes equipped with solar cell and energy harvester. The system uses sleep mode with certain active intervals to save power. The active system interval determined based on the daily energy that can be harvested. Room temperature-humidity data displayed in graphical form via a smartphone application. The daily energy requirements of the system based on the energy consumption of the microcontroller, sensors, and energy loss due to the phenomenon of battery self-discharge. The energy harvester circuit tested with four configurations of the number of turns ratio and resistor values on the transistor base. Each configuration tested at a light intensity of 800–1000 lux. The highest output power produced by the energy harvester configuration is used to determine the daily energy that can be harvested. The results show the harvested daily energy still not sufficient for the system's energy requirements. In future studies, the system's energy requirement will be minimized and the harvested daily energy will be increased.