Lasers, Liquids, and Nanoparticles: Building the Microbots of Tomorrow

A Revolution in Three Dimensions

A collaborative team of researchers from the Max Planck Institute for Intelligent Systems and the National University of Singapore recently unveiled a transformative fabrication method. This approach, dubbed “optofluidic 3D micro- and nanofabrication,” marries traditional photopolymer templates with a sophisticated “infusion” of various nanoparticles.

How It Works

The process begins with two-photon polymerization—a standard technique—to create a porous, three-dimensional skeleton. Researchers then submerge this frame into a liquid teeming with building-block particles. An ultra-short laser pulse heats the fluid locally, sparking micro-scale currents. These flows drive the nanoparticles toward the template walls, packing them into pores like grains of sand in a microscopic mold.

Once the assembly finishes, scientists can dissolve the polymer template. What remains is a self-supporting structure of densely packed nanoparticles, held together primarily by van der Waals forces. If the structure requires extra strength, a quick heat treatment further solidifies the connections between particles.

As the authors emphasize in their paper published in Nature, this method “enables the rapid and highly localized assembly of nanoparticles of diverse shapes and compositions—including metals, metal oxides, carbon nanomaterials, and quantum dots—into complex 3D microstructures.”

According to the Max Planck Institute for Intelligent Systems, this method enables the printing of structures from a wide range of materials—sometimes even in combination—overcoming the previous limitations of polymers. This technology can now be used to construct tiny microrobots that researchers can control magnetically or with light.

The Future of Micro 3D Printing Beyond Plastics

Until now, high-resolution printing at this scale relied almost exclusively on light-sensitive resins. While this tech produced stunning microscopic Eiffel Towers and tiny sculptures, they were essentially just bits of plastic. They looked impressive under a microscope, but their functional use was limited.

The new technique shatters this material barrier. While the template still starts as a polymer, the functional heart of the device can consist of almost any material—metals, semiconductors, or carbon-based structures. Instead of merely “printing” a single material, scientists now precisely “assemble” complex machines by controlling the flow within the template’s pores.

Medicine in the Micro-Scale

This discovery opens vast horizons, particularly in the realm of medical diagnostics. By printing precise micro-valves and filters, engineers can design diagnostic tools that are both more complex and cheaper to produce. These tiny valves could one day sort individual cells or proteins at a patient’s bedside, providing instant results.

Microbots on a Mission

The most exciting application, however, lies in drug delivery. Future microbots could act as active transport vehicles, traveling through the bloodstream to reach a specific tumor or site of inflammation. Because they can combine multiple materials, a single robot might respond to several triggers simultaneously—such as magnetic fields, light, or the chemical makeup of its environment.

This technology also paves the way for a new generation of robots capable of navigating unreachable environments, from deep soil layers to the inner workings of industrial machinery, with a level of control previously reserved for much larger hardware.

Our new technology allows us to form tiny 3D objects from almost any material. It opens new possibilities for multi-functional microbots and other applications that, until today, sounded like science fiction.

– concludes Metin Sitti, former director at the Max Planck Institute for Intelligent Systems.

While the process currently remains in the laboratory stage, the next challenge involves scaling up production. Researchers are already working to optimize template designs and laser scanning to prevent clogging and maintain high resolution. Despite these hurdles, early experiments suggest that this advanced micro 3D printing method will soon integrate into hybrid production lines, forever changing how we build the smallest tools of the future.

Read this article in Polish: Laser, ciecz i nanocząstki. Tak powstają mikroroboty przyszłości