A GMR-Based Smart Respiration Belt for Noninvasive Real-Time Monitoring

Respiration rate (RR) is a vital physiological parameter, yet conventional measurement methods are often invasive, inaccurate, or unsuitable for continuous monitoring. This paper presents a wearable respiration monitoring belt for continuous and non-invasive measurement of breathing activity. The system employs a giant magnetoresistance (GMR) sensor with a paired neodymium magnet to detect chest movements, with the optimal spacing determined through finite element simulations. An instrumentation amplifier, equipped with a DC servo-loop, and a low-pass filter enable robust signal acquisition, while a microcontroller computes the respiration rate in real time. Validation on 12 healthy volunteers showed a maximum error of$\pm 2$breaths per minute compared with a BIOPAC reference, confirming accuracy and stability. Owing to its compact size, low power consumption, and skin-contact-free operation, the proposed system shows strong potential for applications in remote healthcare, sleep apnea detection, and automotive safety.