A new roadmap outlines how advances in propulsion, control, and design are positioning micro and nanorobots for use in medicine, environmental cleanup, and sensing technologies.
(Nanowerk Spotlight) In 1959, physicist Richard Feynman posed a provocative challenge: could machines be built small enough to operate at the molecular scale? Years later, the film Fantastic Voyage imagined a miniature vessel traveling through a human body. These ideas raised serious scientific questions that would shape decades of research. At the scale of bacteria, familiar rules of motion no longer apply. Inertia gives way to viscous drag, conventional engines become unusable, and surface interactions dominate. Building functional machines at this level requires new approaches to materials, propulsion, and control.
Early efforts showed proof of concept but fell short of practical use. Many designs depended on chemical fuels unsuitable for biological or environmental conditions. Others could not sustain motion, respond to external guidance, or operate outside of idealized lab setups. Complex systems like blood, contaminated water, or industrial fluids introduced challenges that these early prototypes could not overcome. As a result, functional deployment remained theoretical.
That has begun to shift. Improvements in fabrication techniques, wireless actuation, hybrid materials, and bioinspired structures are enabling a new generation of micro- and nanorobots. These devices can now operate in real environments—including the human body, polluted ecosystems, and microfluidic diagnostic systems—where they carry out targeted transport, sensing, and manipulation. Some are powered by enzymes that extract energy from their surroundings. Others respond to magnetic or acoustic fields with directional control. As these capabilities grow, the field is moving from concept to implementation.
To assess this transition, a review paper published in ACS Nano (“Technology Roadmap of Micro/Nanorobots”) provides a comprehensive synthesis of current technologies and future pathways. The roadmap spans multiple sectors: medical therapy, environmental remediation, chemical sensing, and industrial processing. It organizes progress around six core areas—propulsion, control, materials, collective behavior, functional integration, and deployment—and outlines the remaining barriers to broader application.
Propulsion is a fundamental challenge. Internally powered robots often rely on catalytic or enzymatic reactions. Some decompose hydrogen peroxide or urea to generate thrust from gas bubbles. Others use asymmetric surface reactions to create directional forces. These fuel-based systems have been adapted for biocompatibility and environmental safety, with designs that function in bodily fluids or natural water sources. Externally powered robots respond to magnetic, acoustic, electric, or optical fields. Magnetic helical swimmers can navigate through viscous fluids and have been guided in living tissues and narrow channels. Acoustic actuation moves particles by ultrasound-generated flows and has been used to mobilize nanowires for sensing. Light and electric fields also offer precise control over movement, especially in structured or enclosed environments.
Control strategies have become increasingly adaptable. Robots can follow chemical gradients, respond to temperature or pH changes, and be guided in real time using magnetic or acoustic fields. Some use logic rules or feedback loops to navigate complex terrain. These capabilities are important not only in biological tissue but also in chemical processing streams or environmental monitoring, where robots must track and respond to specific targets or contaminants.
Cargo handling and task performance are essential to application. In medicine, robots have delivered drugs and genetic material to specific tissue regions or into individual cells. In environmental contexts, robots can collect or degrade pollutants, either by carrying active agents or by catalyzing reactions themselves. In analytical sensing, robots have been shown to detect DNA sequences or chemical markers by changes in motion or signal output. These functions are increasingly being combined with mobility to enable mobile assays, sample acquisition, and real-time diagnostics in fluid systems.
Collective behavior adds another layer of functionality. Swarms of microrobots can self-organize, cooperate, and perform distributed tasks. These behaviors are guided by shared environmental cues, local interactions, or field-based coordination. In one use case, multiple robots form dynamic assemblies to increase capture efficiency during pollutant removal. In sensing applications, coordinated units can scan large volumes, identify concentration gradients, or triangulate signals with higher resolution than a single unit.
Materials define both what a robot can do and where it can safely operate. Rigid metals and semiconductors offer durability and structural complexity, while soft polymers and hydrogels provide flexibility and biocompatibility. For biomedical use, degradable materials reduce the risk of long-term accumulation. In environmental systems, nontoxic and inert compounds are prioritized to avoid secondary contamination. Multi-material designs are becoming more common, allowing robots to combine hard and soft elements, responsive surfaces, and embedded magnetic or catalytic components. Fabrication methods such as glancing angle deposition, two-photon polymerization, and soft lithography now support increasingly sophisticated structures at small scales.
The roadmap also addresses the realities of real-world use. Many microrobotic systems remain confined to controlled research environments. Bridging the gap to deployment requires standardization, scalable production, robust performance in varied conditions, and clear regulatory pathways. For medical devices, this includes toxicology studies, safety assessments, and integration with existing treatment protocols. In environmental and industrial settings, stability, lifetime, recovery, and cost-effectiveness become critical factors.
Importantly, Ju et al. emphasize that these robots are not confined to a single field. The same platform used to deliver drugs in tissue may also be adapted to monitor water quality, conduct chemical reactions in microreactors, or perform sampling in hazardous environments. This modularity gives the technology range but also places demands on flexibility, testing, and adaptation.
The roadmap offers a clear picture of how far the field has come and what it will take to reach wider use. Many of the necessary components—motion, sensing, actuation, material design—have matured. What remains is integration and scale. Microrobots are not yet routine tools, but they are no longer speculative. Whether operating in blood, wastewater, or chemical analysis systems, they are approaching the point of functional utility. This review maps the coordinated progress across disciplines that will be required to bring these capabilities from isolated demonstrations to real-world platforms.
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