In Planta Tattoo and Kirigami Sensors for Self-Powered Monitoring of Vapor Pressure Deficit and Growth Dynamics

We report a scalable, self-powered in planta sensor platform for continuous monitoring of plant hydration and growth. The system integrates two components a leaf mounted tattoo sensor for estimating vapor pressure deficit and a kirigami inspired strain sensor for tracking radial stem growth. Uniquely, the tattoo sensor serves a dual function measuring temperature and humidity beneath the leaf surface while simultaneously harvesting power from ambient moisture via a vanadium pentoxide nanosheet membrane. This moist-electric generator configuration enables energy-autonomous operation, delivering a power density of 0.1114 miroW per square cm. The V2O5 based sensor exhibits high sensitivity to humidity and temperature, enabling accurate VPD estimation for over 10 days until leaf senescence. The eutectogel based kirigami strain sensor, wrapped around the stem, offers a gauge factor of 1.5 and immunity to unrelated mechanical disturbances, allowing continuous growth tracking for more than 20 days. Both sensors are fabricated via cleanroom-free, roll to roll compatible methods, underscoring their potential for large-scale agricultural deployment to monitor abiotic stress and improve crop management.