A unified mechano-ionic skin for resolving native electromechanical coupling

The beat-to-beat electromechanical coupling between cardiac excitation and arterial pulse propagation encodes vital cardiovascular insights, but resolving this coherence in wearables is hindered by the spatial decoupling of sensors and attenuated epidermal signals. Here, we report a unified mechano-ionic skin that preserves this coherence through conducting biopotentials and efficiently transducing arterial pressures along a single ion-conducting pathway. By synergizing molecular cation tethering with microscale stress concentration, our design breaks the symmetry of ion dynamics. This yields a giant piezoionic sensitivity of 1071 mV kPa^-1, exceeding state-of-the-art ionic conductors by over two orders of magnitude. This response resolves pulse waves and electrocardiograms simultaneously, eliminating cross-sensor synchronization errors. Implemented in a wristband, the interface enables beat-to-beat blood pressure monitoring and repeatedly tracks cardiovascular functions under daily resting conditions, demonstrating multimodal sensory fusion can be engineered as an intrinsic property of soft matter by precisely regulating ion dynamics.