According to a study published in Nature Communications, researchers at the University of Colorado Boulder have developed a novel method for creating and controlling tiny particles that can move and function like microscopic robots, providing a potent tool with applications in biomedical and environmental research.
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The study describes a new fabrication approach that combines high-precision 3D printing, known as two-photon lithography, with a microstenciling technique. The team prints the particle and its stencil together before depositing a small layer of metal, such as gold, platinum, or cobalt, via the stencil's openings. After the stencil is removed, a metal patch remains on the particle.
The particles, which are invisible to the naked eye, can be shaped in any way and have surface patches as small as 0.2 microns, which is more than 500 times smaller than a human hair. When subjected to electric or magnetic fields, as well as chemical gradients, the metal patches control particle movement.
The shape of surface patches gives particles information about where to go. We've not had good methods to control the shape of those patches until now.
Wyatt Shields, Study Author and Assistant Professor, University of Colorado Boulder
These particles may be able to improve the way medications pass through human organs, increasing their overall efficacy, or they may be able to assist clean up polluted areas.
In addition to two undergraduate students, Zoe Cruse, who is majoring in chemical and biological engineering and computer science, and Alisha Kumari, who is majoring in biomedical engineering, the study team also consists of first author Kendra Kreienbrink, a materials science and engineering PhD student in the Shields Lab.
Shields concluded, “This study not only represents the exciting things that can be accomplished in active particles and microrobots using non-conventional microfabrication, but that the inclusion and mentorship of undergrads early in research can lead to innovative outcomes.”
Journal Reference:
Kreienbrink, K, M., et al. (2025) Precise surface patches on active particles of arbitrary shape through microstenciling. Nature Communications. doi.org/10.1038/s41467-025-61218-x.