Highly Stretchable but Strain-Insensitive Pressure Sensors for Crosstalk-Free Arterial Pulse Monitoring

Flexible pressure sensors are widely used in wearable devices due to their inherent softness and high sensitivity. However, they often suffer from signal crosstalk caused by deformation during use, especially in dynamic and continuous measurement scenarios. In this work, we present a novel design for highly stretchable yet strain-insensitive pressure sensors, based on ultra-thin PZT sheets and strain-gradient substrates. In this design, the PZT sensing unit is strategically positioned within a strain-constrained region of the substrate, effectively isolating it from substrate-induced strain and eliminating its influence on the sensor's output voltage. As a result, the sensor maintains stable sensing performance under large tensile strains. Our sensor demonstrates high strain insensitivity under tensions up to 93%, along with a low detection limit of 15 mN. We further developed a pulse-monitoring tape incorporating the proposed sensors and demonstrated its application in continuous, crosstalk-free arterial pulse monitoring, heart rate tracking, and real-time alerts during daily activities. This sensor provides a promising solution for crosstalk-free physiological monitoring in next-generation wearable devices.