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Real-time Respiration Measurement during Sleep Using a Microwave Sensor

Non-contact continuous respiratory monitoring during sleep is of high usability to early disease detection and daily health monitoring. This study introduces a novel microwave sensor prototype for real-time respiration measurement. The antennas of the sensor are placed below the bed sheet, and function by transmitting a series of microwave signals to detect the inhale-exhale body motions while breathing. Compared to other remote wireless monitors, our sensor is less interfered by environmental noises as well as without direct contact with the body. The received I/Q signals are merged into one output and process to detect the frequency of breathing. The performance is evaluated using overnight sleep data and compared with ground-truth data measured by standard PSG airflow sensor. Result achieves high detection rate of 98.88% with mean squared error (MSE) of 1.23 over 420 one-minute recordings. In addition, the sensor is able to detect respiration accurately regardless of a person’s sleep position. We demonstrate that our microwave sensor is robust and usable for real-time respiratory monitoring.