Molecularly Engineered Quaternized <i>κ</i> ‐Carrageenan: a Multifunctional Platform for Atmospheric Water Harvesting, Moisture‐Electricity Generation, and Self‐powered Wearable Sensors

Abstract The pursuit of sustainability in the energy and environmental fields, coupled with the innovation in intelligent wearable sensing technologies, demands high‐performance materials with advanced functionalities. Molecular design has emerged as a cornerstone for optimizing material properties and achieving multifunctional integration. Natural carrageenan, a green substrate material known for its biocompatibility and renewability, faces challenges due to its limited processability and mechanical robustness. In this study, zwitterionic groups are introduced through molecular design to regulate intermolecular interactions, significantly lowering the sol–gel transition temperature, thus enabling superior processability and enhanced mechanical properties. This modification strategy enables efficient salt ion immobilization, endowing the material with outstanding atmospheric water harvesting (AWH) capabilities (2.1 g g − ¹) and stable moisture‐electricity generation (MEG) performance (0.9 V of V oc ). Leveraging these advancements, a self‐powered smart sensor is developed, capable of real‐time monitoring of respiratory states, pressure sensing, and rapid response to noncontact actions. This work provides an integrated material design framework that facilitates innovation in green energy and personalized health monitoring technologies.