Recent Trends in Human Breathing Detection Using Radar, WiFi and Acoustics

Human breathing is a vital physiological process that reflects the health status, activity level, and emotional state of a person. It can also be used as a biomarker for detecting living persons in disaster scenarios or hidden persons behind wall. However, human breathing detection is not a trivial task, as it involves various challenges, such as noise, interference, movement, and device compatibility. In this paper, we review the existing methods and techniques for human breathing detection, which we have broadly classified into contact-based and contactless approaches. Contact-based approaches require physical contact between the subject and the device, such as a stethoscope, a microphone, or a sensor. Contactless approaches use wireless signals, such as radar waves, WiFi signals, or sound waves, to remotely sense the breathing activity of the target. We compare and contrast the advantages and disadvantages of both approaches, and discuss their weakness and limitations in different fields, such as health care, security. We also identify some of the emerging or future trends in human breathing detection, such as passive sound capturing using smartphone, artificial intelligence. We conclude by highlighting some of the key challenges that need to be addressed in this field.