A robust PPG foundation model using multimodal physiological supervision

Summary

Pretrains a PPG-only foundation model (1D ResNet-26 encoder) on MIMIC-III Waveform Database Matched Subset (10,282 ICU patients, 125 Hz) using co-recorded ECG and respiration signals only to select which PPG windows count as contrastive positives/negatives during training — five summary metrics from ECG/RESP per 10s window build a "physiological metric space," and windows close in that space become positive pairs. At inference, only PPG is used. Explicitly targets robustness to noisy/motion-corrupted PPG, including an IMU-energy-stratified DaLiA noise analysis.