Self-powered floating capsule for decentralized water detection and disinfection

A portable device capable of detecting and disinfecting water without power supplies or chemical additives can provide reliable and equitable access to safe drinking water. Here we develop an all-in-one floating capsule, requiring no external power or chemicals, which monitors chemical pollutants by detecting total dissolved solids (TDS) as surrogates and can disinfect microorganisms, guided by the measured TDS. The capsule converts manual shaking to electrical power for TDS detection and Bluetooth transmission through electromagnetic induction. When TDS levels indicate an acceptable level of chemical safety, the capsule autonomously initiates disinfection. Propelled by gentle movement, the capsule’s dielectric outer shell generates electrostatic charges at the water–dielectric interface. These charges accumulate at the nanorod tips to create intense local electric fields, facilitating disinfection by electroporation. The cost-effective capsule (<US$25) enables rapid detection (3-s shaking) and complete disinfection (>6.0-log removal) in containers over 120 cycles, demonstrating a scalable and energy-independent approach for decentralized water safety monitoring and treatment.