A Flexible and Dual-Channel Sensing System for Long-Term Nasal and Oral Respiration Simultaneously Monitoring

A flexible and dual-channel sensing system is proposed for monitoring nasal and oral respiration simultaneously during sleep. The system consists of a respiratory sensor and a signal processing circuit. The sensitive units of the respiratory sensor are composed of folding metal resistances, which are deposited on flexible substrate by micro-electromechanical system (MEMS) technology, and the working principle is based on the thermal resistance effect. The simulation demonstrates that there is a remarkable temperature difference in the sensitive units between inhalation and exhalation (10 °C and 19 °C for nasal and oral channel, respectively), and the performance tests illustrate that the sensing system has superior sensitivity (9.4 and 19.6 mV for nasal and oral channel, respectively), stability, and anti-interference ability. Also, the system is proved to be able to identify and distinguish various kinds of respiratory diseases, including hypopnea, mouth breathing, and apnea. Therefore, the proposed sensing system can serve as an effective method for health monitoring and early screening of respiratory diseases in the future.