Micro-nano Robots for Wastewater Treatment: Current Application Status and Prospects
Conventional wastewater treatment technologies face persistent challenges including incomplete removal of emerging contaminants, secondary pollution, and low energy efficiency. Micro-nano robots (MNRs), leveraging their self-propulsion, precise navigation, and high specific surface area, offer a transformative approach for targeted pollutant sequestration and degradation. This review systematically examines the operational mechanisms and propulsion strategies of MNRs in wastewater remediation. Through a data-driven bibliometric analysis, we identify chemical propulsion and photocatalytic degradation as the predominant research foci. We critically evaluate the performance of various MNR designs—including chemically driven, magnetically driven, and light-driven systems—for the removal of organic pollutants, heavy metals, microplastics, radioactive nuclides, and pathogenic microorganisms. Representative studies demonstrate removal efficiencies exceeding 90% for specific contaminants, such as uranium preconcentration via metal-organic framework-based microrobots and microplastic removal using self-driven magnetorobots. Despite these advances, MNRs face intrinsic trade-offs between propulsion efficiency and environmental compatibility, as well as challenges in coordinating actuation and control in complex aqueous matrices. We propose future directions emphasizing sustainable energy-harvesting systems and intelligent, reconfigurable multifunctional designs. This review provides a systematic framework and forward-looking perspective to accelerate the translation of MNR technology from laboratory innovation to practical wastewater treatment applications.