A nasal-thermistor based study for continuous monitoring of breathing rate and apnea detection

The proposed study discusses a low-cost respiration rate detection system for continuous health monitoring. The significance of this study relies on the fact that the envisaged system can detect high and low ventilation alongside normal breathing conditions. Moreover, the above system can detect apnea as well. This study employs a thermistor attached to commonly available nebulization mask for primary transduction. The temperature difference between inhaled and exhaled air induces resistance changes in the thermistor, which further changes the output voltage across the above sensor in a potential divider network. Various amplification and filtering techniques are employed to extract a respiratory bio-signal of reasonable quality. A quasi-digital signal corresponding to this bio-signal is obtained. Thus, the respiratory rate can be inferred by measuring the time period of the above-mentioned quasi-digital pulse. The accuracy of the proposed system as a respiratory monitor was verified and compared with the help of a reference bio-instrument. Moreover, the study was conducted in a group of fifteen volunteers of various age groups. The maximum error in measuring RR was less than 1 bpm.