Dual-Path Cuffless PPG-Based Blood Pressure Estimation Using Conformer & Swin Transformer

This study introduces a novel dual-path deep learning framework using Photoplethysmogram (PPG) signals to address key challenges in continuous, non-invasive cuffless Blood Pressure (BP) monitoring. To this end, we introduce -for the first time- the use of two novel deep neural network architectures: Conformer-Transformer and 1D Swin Transformer. These architectures are adapted here to model both the morphological structure and rhythmic dynamics of PPG signals. This cross-domain transfer enables Arterial Blood Pressure (ABP) waveform reconstruction and significantly improves the accuracy and physiological consistency of Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) estimation. Extensive experiments on two public datasets demonstrate that our methods consistently outperform mainstream baselines across multiple key metrics. Specifically, the Conformer-Transformer achieved the lowest Mean Absolute Error (MAE) of 2.979 mmHg for systolic and 1.603 mmHg for diastolic BP, improving upon previous studies by 9.6% and 8.4%, respectively, while delivering the best waveform reconstruction performance too. The Swin Transformer achieved a systolic MAE of 3.034 mmHg and a diastolic MAE of 1.714 mmHg. All experimental results conform to the British Hypertension Society (BHS) grade A and Association for the Advancement of Medical Instrumentation (AAMI) standards.