Research on Calibration Method of Flexible Blood Pressure Sensor Based on Photoplethysmography

The flexible sensor based on photo plethysmo graphy (PPG) can detect heart rate (HR) and blood pressure (BP), but the calibration of their detection results is rarely reported. Therefore, this paper proposes a reflective PPG heart rate detection and blood pressure calibration system based on simulated blood circulation. The peristaltic pump is used to generate pulsating flow,and the frequency and pressure of simulated blood delivery are controlled by adjusting its rotational speed,thus causing the change of the volume of simulated blood in the elastic latex tube and changing the signal period and intensity of reflected light, which is closer to match the actual scenario of human pulse measurement process. The mean value of heart rate detection error of the system is 0.277 78, and the 95% consistency limit is (-2.595 62, 3.151 17). The goodness of fit of measured systolic blood pressure (SBP) and diastolic blood pressure (DBP) are 0.971 85 and 0.981 11, respectively. The mean value of mean deviation (MD) ± standard deviation (SD) of SBP and DBP detected by the calibrated flexible PPG sensor on four volunteers is (1.21±2.16) mmHg and (0.76±2.02) mmHg, respectively, which are in line with and far less than the standard index of 5±8 mmHg for measuring the accuracy of blood pressure monitors set by the association for the advancement of medical instrumentation (AAMI). The results show that this system can calibrate the flexible PPG sensor accurately and efficiently, which provides the calibration basis for the accurate blood pressure detection of por- table wearable devices. © 2024 Chinese Institute of Electronics. All rights reserved.