Real-time breath monitoring using multi-channel MEMS resonator

In this study, a multichannel resonant chemical sensor-based respiration-monitoring system was designed. The system measured the change in humidity inside a fixed-volume chamber caused by respiration over time, using a chemically activated polymer. Poly(allylamine hydrochloride) was selected as the hydrophilic polymer for humidity measurement. Real-time monitoring of simple respiration parameters, such as respiration rate, was achieved. The flow rate of breathing was estimated comparing the measured data and mathematically calculated data. The Nelder-Mead method was employed as the estimation method to predict the respiration pattern. Resting respiration was measured, and respiration parameters were calculated based on these observations. Additionally, respiration during exercise was measured to capture respiration in various states. Exercise intensity was quantified by simultaneously measuring power and heart rate. Measurements were conducted for three intensity levels, ranging from low to high, resulting in an increase in respiration rate from 26 to 37 breaths/min and minute ventilation from 19 to 27 L, respectively.