Light‐Driven Micromotors for Microscale Metal Ion Sensing Applications in Fluid Medium

Abstract Synthetic micromotors are at the forefront of technological advancements, offering innovative solutions for biomedical and environmental challenges. This study presents a unique design of light‐driven micromotors for the localized detection of copper (Cu 2 ⁺) metal ions. These micromotors have a Janus‐shaped spherical structure, featuring multiple layers: a photocatalytic layer for propulsion under UV light (320‐400 nm), a layer of dye molecules for fluorescence emission when excited by blue light (450 nm), and a magnetic‐responsive layer for guided swimming. The fluorescent dye used has the intriguing property of changing its fluorescent behavior in the presence of Cu 2 ⁺ metal ions in solution, allowing the micromotors to selectively and locally detect Cu 2 ⁺ ions. To quantify fluorescence variations, a spectrometer is utilized, confirming the system's sensitivity to metal ions in solutions. Controlled experiments are conducted to optimize and calibrate micromotors for precise Cu 2 ⁺ metal ion detection at targeted locations. The scalable design of these micromotors, featuring dual optical responsiveness and guided swimming, enables precise on‐demand sensing of metal ions. These features present the micromotors as mobile sensor units suitable for environmental remediation and sensing applications in various fields, including lab‐on‐a‐chip devices, water quality assessment, and the regulation of industrial waste disposal into water bodies.