Self-powered floating capsule disinfects drinking water without batteries or chemicals

floating device disinfects through motion

Once the capsule confirms that dissolved solids remain within acceptable levels, it automatically initiates a disinfection process. The device harvests energy from gentle movement, while floating inside a water container, without relying on filters, chlorine, ultraviolet light, or rechargeable batteries.

Its dielectric outer shell accumulates electrostatic charges at the interface between the capsule and the surrounding water. These charges concentrate at microscopic nanorod structures on the capsule’s surface, generating localized electric fields strong enough to disrupt microbial cell membranes through electroporation. The process neutralizes bacteria and other microorganisms without introducing chemical residues into the water.

Laboratory testing demonstrated more than a six-log reduction of microbial contamination, equivalent to eliminating over 99.9999 percent of microorganisms. Researchers  report  that the capsule maintained its performance through more than 120 treatment cycles and operated in containers holding up to four liters of water.

self-powered floating capsule disinfects drinking water without batteries or chemicals - 2a self-powered floating capsule that detects water quality and disinfects microorganisms without batteries | image via Research Communities by Springer Nature

decentralized approach to safe drinking water
The project contributes to growing research into decentralized water technologies that can function independently from large-scale treatment networks. While portable purification systems already exist, many depend on consumable filters, chemical treatments, ultraviolet lamps, or rechargeable power sources. By harvesting energy directly from human motion and environmental movement, the FDGD capsule seeks to reduce those dependencies.

The device points toward potential applications in disaster relief, humanitarian response, outdoor recreation, and remote communities where access to electricity remains limited. Although further testing outside controlled laboratory conditions will be necessary before commercialization, the research proposes an alternative model for water safety that combines monitoring and treatment within a single self-powered object.

7a Circuit diagram of the PMIC and BLE chip. b A schematic showing a bottom view of the FDGD capsule, including the EMG, the PCB plate with PMIC and BLE chip, and the TDS sensor. c Photographs showing the top and bottom views of the PCB plate with the PMIC and the BLE chip.

name: floating-induced detection-guided disinfection (FDGD) capsule

research team: Min Jae Park, Dong-Min Lee, Zheng-Yang Huo, Sungjin Cho, Fengyi Pang, Sung Soo Kwak, Young-Jun Kim, Chris R. Bowen, Ming Xie & Sang-Woo Kim

institutions: Yonsei University, University of Bath, Renmin University of China, Korea Institute of Science and Technology

publication: Nature Water