A Wearable Nose Clip Sensor System for Monitoring Vital Body Signs of Apnea Patients

Respiration is a fundamental physiological process that ensures oxygen supply and carbon dioxide removal to maintain overall well-being. However, some individuals are confronted with various respiratory challenges, such as apnea or ongoing respiratory difficulties. Measuring a single indicator of respiration rate easily led to misdiagnosis of apnea since human respiration was consciously controlled. In this article, a nose clip sensor system based on a temperature/humidity sensor and a photoplethysmography (PPG) sensor was developed for on-line monitoring respiration rate, heart rate (HR), and blood oxygen saturation by clamping onto the nasal wing. The system provided an adaptive calibration module and Savitzky-Golay filter to reduce the impact of individual skin differences for further feature extraction and vital sign calculation, guaranteeing optimal signal quality and thereby enhancing detection accuracy. A clinical trial conducted on 23 patients demonstrated that the proposed device exhibited high accuracies compared with the gold standard care monitor, showing 93.45%, 95.24%, and 89.78% for respiration rate, HR, and blood oxygen saturation, respectively. The nose clip sensor system holds potential for application in monitoring the vital signs and identifying respiratory states of patients with apnea.