Smartphone Dual-Camera based Blood Pressure Screening Using Pulse Transit Time Between Ear and Finger

Area of Science:

• Biomedical Engineering
• Health Informatics
• Mobile Health

Background:

• Smartphones equipped with optical cameras and sensors facilitate physiological signal acquisition.
• Remote health screening is increasingly reliant on accessible mobile technologies.

Purpose of the Study:

• To develop and validate a smartphone-based framework for blood pressure (BP) estimation.
• To utilize dual-camera photoplethysmographic (PPG) signal acquisition for BP monitoring.

Main Methods:

• Synchronous collection of PPG signals from the ear and finger using a smartphone's dual-camera system.
• Calculation of Pulse Transit Time (PTT) between ear and finger PPG signals.
• Estimation of systolic and diastolic BP using personalized regression models based on PTT, heart rate, and heart rate variability, with a random forest model.
• Comparison of smartphone-derived BP estimates against cuff-based measurements.

Main Results:

• The best performance was achieved using PPG-derived physiological information (PTT, heart rate) with a random forest regression model.
• Mean absolute errors for systolic and diastolic BP were 3.74 mmHg and 2.73 mmHg, respectively.
• High Pearson correlation coefficients (0.877 for systolic, 0.868 for diastolic) were obtained, validating the accuracy of the method.

Conclusions:

• A smartphone dual-camera system can feasibly screen blood pressure.
• The proposed framework demonstrates potential for non-invasive, convenient BP monitoring.
• Integration of PPG signal analysis on smartphones offers a promising avenue for remote health assessment.