Researchers at the University of Würzburg have built nanorobots powered purely by light that can hunt down, grab and move bacteria in liquid. The work was published in August 2026 in Nature Communications. It is a rare example of such precise, selective manipulation at the single-cell level.
Key takeaways
- The robots are smaller than a micrometer — about 50 times thinner than a human hair.
- Propulsion comes from photon recoil: absorbed and redirected light creates a tiny thrust.
- Light polarization steers them, and the robots make rapid 90-degree turns.
- Up to four plasmonic nanoantennas absorb polarized light of a specific color and emit it directionally.
- The work was led by Professor Bert Hecht's team, and results are confirmed in vitro only for now.
How light-driven propulsion works
Instead of chemical fuel or a magnetic field, the nanorobot is driven by light itself. Each absorbed photon is redirected and creates a small recoil — much like the kick of a fired gun. Absorption happens through up to four plasmonic nanoantennas?plasmonic nanoantennas: nanoscale optical antennas that absorb and directionally re-emit light that capture polarized light of a specific color and emit it directionally.
Steering is just as elegant. The antenna wires align themselves with the polarization of the incoming light. By changing the polarization, the researchers rotate the robot while photon recoil pushes it forward. The result is very fast 90-degree turns and efficient scanning of large sample areas.
What it can do in practice
The robot selectively grabs, carries and releases bacteria. It handles even larger cell clusters, slowing under load while staying fully steerable. That sets it apart from many microrobots driven by chemical reactions or magnetic fields, where precise, selective control is harder to achieve.
In essence, we have built a light-driven nanorobot that can track down and collect bacteria.
Jin Qin, lead experimental scientist, Julius-Maximilians-Universität Würzburg.
Why it matters
Selective grabbing and transport of individual bacteria without chemical fuel opens a new class of tools for microbiology and biomedical research. Control by light alone offers precision that chemical or magnetic propulsion struggles to match. It is still a lab result, but it shows optical control of matter at the microscale becoming a real research toolkit rather than just a flashy demo.
What's next
- The next step is moving from in vitro conditions to more complex biological environments.
- The authors point to potential uses in microbiology, biomedicine and precise microscale material manipulation.
- Full data and methodology are described in Nature Communications (DOI 10.1038/s41467-026-70685-9).
Sources
- ScienceDaily — Tiny Robots Powered by Light Can Hunt Down and Collect Bacteria
- Nature Communications — 10.1038/s41467-026-70685-9
