Contactless 12-lead electrocardiogram via deep computational radar

Figures

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  Fig. 1. Overview of the CardioRadar system. a Modular radar device with two stacked PCBs: the upper integrates the radar chip for signal acquisition, and the lower handles wireless communication. Each PCB is 6 cm in diameter and combines commercial components with custom circuitry. b The system uses an LFMCW radar at 60 GHz with 4 GHz bandwidth and a 3 × 4 MIMO virtual array, producing 15 × 12 I/Q data per frame. c The radar is positioned 0.5 m from the subject for continuous contactless cardiac monitoring. d Contactless sensing captures chest vibrations from both respiration and heartbeat; 3D beamforming isolates cardiac motion for precise detection. e Filtered phase and I/Q signals at a selected spatial point with synchronized ECG lead. f Example of reconstructed 12-lead ECG showing atrial fibrillation features.

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  Fig. 2. Overall performance of reconstructed 12-lead ECG. a The 12-lead ECG records cardiac electrical vectors from various angles across the frontal plane (using limb leads I, II, III, aVR, aVL, aVF) and horizontal plane (through precordial leads V1-V6). b Correlation distribution with KDE peak at 0.80 and IQR = 0.14 (P25 = 0.69, P75 = 0.83), shown with KDE (blue) and CDF (red). c Different metrics for reconstructed 12-lead ECG. d An example of reconstructed 12-lead ECG.

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  Fig. 3. Prediction performance across demographics, cardiac conditions, and ECG leads. a Performance varies by age and gender, with male youth and females in prime working age achieving the highest correlation. Both metrics remain stable across groups. b Performance across cardiac conditions shows lower results for VPB, CRBBB, and AF due to their limited number of samples, but predictions still remain comparable to others. c Performance across different leads with strong statistical reliability across leads (P < 0.001 for 97% of samples).

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  Fig. 4. Examples of reconstructed ECG signals for various abnormalities. a SB: accurate rhythm abnormality detection with predicted IBIs closely matching ground truth. b STach: consistent rhythm tracking with accurate IBI estimation. c AF: irregular RR intervals, absent P waves, and undulating f-wave baseline. d STC: horizontal ST depression reflecting ischemia. e TAb: bifid T-wave morphology in Lead III. f CRBBB: RSR' morphology and prolonged QRS reproduced in Lead V3. g Feature separability: radar- and ECG-derived signals show comparable performance.

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  Fig. 5. Long-term monitoring performance. a Reconstructed ECG signals over an entire night of monitoring for a 32-year-old male, showing a limb lead (II) and a precordial lead (V4), with momentary correlation coefficients averaged over 2 s. b Predicted IBI closely matches the true IBI, capturing transient changes during sleep. c Correlation between reconstructed and ground truth ECG across leads, with a mean correlation of 0.81 and a median of 0.84. Modified limb leads used by the Holter ECG result in amplitude differences compared to reconstructed signals. d An example of a 20-s segment of reconstructed ECG signals.