Smart micro- and nanorobots for water purification

Abstract

Less than 1% of Earth’s freshwater reserves is accessible. Industrialization, population growth and climate change are further exacerbating clean water shortage. Current water-remediation treatments fail to remove most pollutants completely or release toxic by-products into the environment. The use of self-propelled programmable micro- and nanoscale synthetic robots is a promising alternative way to improve water monitoring and remediation by overcoming diffusion-limited reactions and promoting interactions with target pollutants, including nano- and microplastics, persistent organic pollutants, heavy metals, oils and pathogenic microorganisms. This Review introduces the evolution of passive micro- and nanomaterials through active micro- and nanomotors and into advanced intelligent micro- and nanorobots in terms of motion ability, multifunctionality, adaptive response, swarming and mutual communication. After describing removal and degradation strategies, we present the most relevant improvements in water treatment, highlighting the design aspects necessary to improve remediation efficiency for specific contaminants. Finally, open challenges and future directions are discussed for the real-world application of smart micro- and nanorobots.

Metal oxide single-component light-powered micromotors for photocatalytic degradation of nitroaromatic pollutants

“…Photocatalysis is a promising lightdriven AOP technology, necessitating a photocatalyst and proper light irradiation to generate ROS that break down organic pollutants. Recently, nanostructured TiO 2 , ZnO, and Fe 2 O 3 photocatalysts have received great interest [12][13][14][15][16][17] . For instance, Reddy et al proposed Cu-doped ZnO nanoparticles for RhB dye degradation under light irradiation 18 .…”

In vivoapplications of micro/nanorobots

“…Off-board actuation methods significantly differ from on-board methods with the requirement of utilizing external power sources (magnetic fields, acoustic waves, and light irradiation) for propulsion. 49 Among these sources, magnetic actuation is the leading way to precisely manipulate micro/nanorobots with high degrees of freedom (DoF). 50,51 Given the high penetration ability of magnetic fields, this approach is especially attractive for biomedical applications requiring precisely controlled motion in deep tissues.…”

Light-powered swarming phoretic antimony chalcogenide-based microrobots with “on-the-fly” photodegradation abilities

“…Microrobots are autonomous micro-scaled devices that are designed to accomplish a specific mission on microscale. 1–3 Microrobots are chemically programmed to collect, transport, and deliver cargo, 4–6 degrade pollutants 7,8 and bacterial contamination, 9,10 or sense desired substances, 11,12 etc . However, a single microrobot exhibits relatively poor efficiency when studied in the macro-scale.…”