Shape-Shifting Microrobots That Brush, Floss, and Diagnose

The Biofilm Challenge

Biofilms—sticky communities of bacteria, fungi, and other microbes—are notorious for clinging tightly to surfaces. In the mouth, they form dental plaque, which can cause cavities and gum disease. In hospitals and industry, biofilms contribute to infections and equipment damage. The problem isn’t just getting rid of them; it’s also being able to sample biofilms accurately to detect pathogens hiding in hard-to-reach spots. Traditional tools often fall short when surfaces are irregular or covered in crevices, like human teeth.

Enter STARS: Robotic Superstructures

Researchers led by Hyun Koo and colleagues developed a new approach using Surface Topography-Adaptive Robotic Superstructures (STARS)—shape-shifting microrobots made from iron oxide nanoparticles. Guided by magnetic fields, these nanoparticles assemble into flexible “bristles” that can extend, bend, and reconfigure to fit the contours of complex surfaces.

These robotic bristles aren’t just brushes. They combine mechanical scrubbing with chemical disinfection, thanks to their ability to activate hydrogen peroxide and release bacteria-killing free radicals directly on the biofil.

Toothbrushing and Flossing—Reimagined

In experiments with 3D-printed and real human teeth, STARS bristles showed remarkable versatility. They could sweep across flat surfaces like a toothbrush and slip between teeth like dental floss, adapting their length and stiffness in real time.

Tests revealed that STARS removed more than 90% of sticky biofilms, killed bacteria on contact, and captured microbial fragments for further analysis. In other words, they clean and sample at the same time.

A Diagnostic Bonus

As the bristles scrub, they trap pieces of bacteria, fungi, viruses, and extracellular material. These captured samples can then be analyzed to detect multiple types of pathogens at once. This “dual-action” capability makes STARS not just a cleaning device, but also a diagnostic tool—a feature that could be valuable for personalized medicine and early infection detection.

Why It Matters

The idea of autonomous, adaptive microrobots that can brush, floss, and diagnose in real time opens the door to a new era of oral care. Beyond dentistry, the same principles could be applied to biofilm problems in medical devices, pipelines, or water systems.

The authors envision future STARS-based devices that operate without manual effort  potentially helping people with disabilities maintain oral hygiene or even self-guided.

Reference

Oh, M. J., Babeer, A., Liu, Y., Ren, Z., Wu, J., Issadore, D. A., Stebe, K. J., Lee, D., Steager, E., & Koo, H. (2022). Surface Topography-Adaptive Robotic Superstructures for Biofilm Removal and Pathogen Detection on Human Teeth. ACS Nano, 16(8), 11998–12012. https://doi.org/10.1021/acsnano.2c01950