A low-power, high-sensitivity CMOS-MEMS flow sensor for respiration health evaluation

In this paper, we present a fast-response thermal flow sensor (TFS) with low power consumption and high sensitivity, fabricated using CMOS-MEMS technology. To enhance sensitivity and reduce power consumption, we propose a lithography-free, self-aligned post-CMOS fabrication process. Characterization results demonstrate that the fabricated flow sensor achieves high thermal efficiency, achieving an overheat temperature rise ( ΔT h ) of 58.76 K while maintaining power consumption below 1 mW. The sensor also exhibits a high normalized sensitivity of 2131 mV m −1 s W −1 , a low minimum detection limit of 0.88 mm s −1 , and a rapid response time of 1.7 ms @ 1.67 m s −1 . The sensor was subsequently incorporated into a Portable Pulmonary Function Monitoring (PPFM) system, incorporating a by-pass channel to enable a broad measurement flow range (±1000 SLM) suitable for medical applications. Leveraging the high-performance sensor and an optimized flow channel design, the PPFM setup achieves an enhanced resolution of 28.5 mL s −1 and a significantly improved volume error of 1.6%. Experimental results validate the efficacy of the proposed TFS and PPFM system, demonstrating its potential as a promising sensing technology for pulmonary disease diagnostics and medical applications, particularly in remote or resource-limited settings.