Circuit-free cardiovascular monitoring via skin-interfaced nanophotonics

Abstract

Continuous cardiovascular monitoring is essential for managing circulatory health and disease, yet most wearable sensors are constrained by reliance on electrical transduction and built-in electronics. We present a circuit-free, wholly optical approach using diffraction from a skin-interfaced nanostructured surface to detect minute skin strains from the arterial pulse. A smartphone camera records the shifting diffraction pattern in real time, removing the need for spectrometers or other optical hardware. In phantom and human studies, we recovered high-fidelity arterial pulse waves and detected benign arrhythmic events in close agreement with a clinical reference. Derived waveforms captured features linked to arterial stiffness, a key cardiovascular risk marker. Our approach uses battery-free, cost-effective, and disposable platforms enabling scalable monitoring for healthcare and broad consumer applications.