Towards Accurate, Cost-Effective, Ultra-Low-Power and Non-Invasive Respiration Monitoring: A Reusable Wireless Wearable Sensor for an Off-the-Shelf KN95 Mask

Abstract

Respiratory rate is a critical vital sign that indicates health condition, sleep quality, and exercise intensity. This paper presents a non-invasive, ultra-low-power, and cost-effective wireless wearable sensor, which is installed on an off-the-shelf KN95 mask to facilitate respiration monitoring. The sensing principle is based on the periodic airflow temperature variations caused by exhaled hot air and inhaled cool air in respiratory cycles. By measuring the periodic temperature variations at the exhalation valve of mask, the respiratory parameters can be accurately and reliably detected, regardless of body movements and breathing pathways through nose or mouth. Specifically, we propose a voltage divider with controllable resistors and corresponding selection criteria to improve the sensitivity of temperature measurement, a peak detection algorithm with spline interpolation to increase sampling period without reducing the detection accuracy, and effective low-power optimization measures to prolong the battery life. The experimental results have demonstrated the effectiveness of the proposed sensor, showing a small mean absolute error (MAE) of 0.449 bpm and a very low power consumption of 131.4 μW. As a high accuracy, low cost, low power, and reusable miniature wearing device for convenient respiration monitoring in daily life, the proposed sensor holds promise in real-world feasibility.

Laser spectroscopic method for remote sensing of respiratory rate

“…Furthermore, the average overall uncertainty for all displacements considered in this work was found to be well below 5%. This uncertainty level is comparable to existing respiratory monitors [ 24 ]. As a result, precise measurement of the frequency can be attained.…”

Healthcare Monitoring Using Low-Cost Sensors to Supplement and Replace Human Sensation: Does It Have Potential to Increase Independent Living and Prevent Disease?

“…In addition, airborne infectious diseases can be transmitted through face-to-face contact (e.g., talking, coughing, or sneezing). A noncontact detection system with protection (e.g., wearable temperature measurement integrated into face masks) may effectively limit the spread of respiratory viruses, such as COVID-19 or seasonal influenza [ 20 ].…”

“… Summary of typical algorithms used for processing data acquired by low-cost sensors including LR [ 20 ], DT [ 21 ], FFT [ 22 ], SVM [ 22 ], NB [ 23 ], SA [ 29 ], WT [ 34 ], LDA [ 40 ], ANN [ 42 ], HMM [ 56 ] and KNN [ 65 ]. …”

Embedded Electronic Sensor for Monitoring of Breathing Activity, Fitting and Filter Clogging in Reusable Industrial Respirators

“…Industrial respirators and face masks are a key implement to develop wearable breathing monitoring systems. Xu et al [ 18 ] developed a small sensor to be used in the exhalation valve of a KN95 mask. The sensor measures the periodic airflow temperature variations caused by exhaled hot air and inhaled cool air in respiratory cycles.…”