A Smart Dual-Thermistor-Based Nasal Mask for Respiratory Health Monitoring

In this letter, we propose a low-cost, portable, and wearable smart nasal thermistor mask with associated electronics for continuous respiration monitoring. A commercially available mask incorporating a thermistor realizes the smart mask. The abovementioned thermistor, along with another thermistor for ambient temperature monitoring, together realize a dual-thermistor bridge. The output voltage of the bridge topology interfacing the above dual thermistor is amplified using an instrumentation amplifier stage. The above signal was signal-conditioned, and the respiration rate of the subject was inferred. The accuracy in measurement was tested using 20 healthy volunteers of various age groups. The resulting error was less than 1 breaths per minute. The developed prototype was tested with different states of the subject, likewise during exercise and during a short nap. A comprehensive sensitivity study of the acquired biosignal was performed for different positions of sensor placement. The potential applications of the smart mask include integration with telemedicine, advanced driver assistance systems, and in space applications.