Design of Human Passage Detector Based on Simultaneous Wireless Information and Power Transfer Structure

This paper presents a human passage detector that uses Simultaneous Wireless Information and Power Transfer (SWIPT) technology to simultaneously harvest energy and detect human crossings. Our research presents a novel battery-free sensor capable of distance estimation with single-sensor, featuring low power consumption (1.7 μA) and a remarkable 10 km data transmission range using the LoRa protocol. The architecture includes a battery-free sensor node that receives power from an RF source at 915 MHz and uses a microprocessor to sample the attenuated signal caused by human passage. Sampled data is sent to the central node for distance estimation using machine learning methods. The paper introduces four different designs, with the one exhibiting low power consumption being highly recommended. Our experiments show that the patch antenna exhibits superior stability in the presence of obstacles due to its directionality and has a higher energy storage capacity in the capacitor. This study explores the impact of a person's movement on Received Signal Strength Indicator (RSSI) when deviating from the sensor-RF source line of sight. The attenuation and duration of RSSI vary based on the person's distance from the sensor. Experimental validation demonstrates a 99.54% estimation success rate for training data at two distances and 94.89% for training data at three distances.