Textile Stretchable Antenna-Based Sensor for Breathing Monitoring

Breathing rate is a crucial vital sign for evaluating well-being and identifying underlying diseases related to the respiration system. This article presents a fully stretchable triangular loop antenna-based sensor for real-time respiration monitoring. This antenna is integrated into a commercially available T-shirt, which is made of stretchable conductive ink printed on a thermoplastic polyurethane (TPU) substrate. The sensing mechanism is influenced by shifts in the resonance frequency of a triangular loop antenna sensor, which occurs due to thoracic and abdominal deformation during the breathing cycle of inspiration and expiration. The proposed system captures breathing patterns by detecting shifts in the resonance frequency, which are continuously recorded in real-time via MATLAB. The vector network analyzer (VNA) was connected to a remote PC via a LAN interface to store the breathing data on a PC host, facilitating data transfer over TCP/IP through the same LAN interface. The proposed antenna-based sensor stands out for its lightweight structure making it convenient to embed in clothing and its ability to provide continuous monitoring of different breathing patterns including eupnea, bradypnea, tashypnea, ataxic, sighing, and Biot’s breathing. The proposed system was tested through experimental measurements, and the obtained results matched well with the standard breathing patterns provided by the World Health Organization.