Since tardigrades are known for their extreme survival abilities — from boiling heat to the vacuum of space — adapting a biocompatible marking system could be beneficial for tracking individual specimens, studying their biological responses, or even testing novel materials that interact with microscopic organisms.
Micro- and nanofabrication have transformed photonics and electronics, but traditional methods don’t work well with living organisms. The main issues are rigid coatings, radiation damage, and toxic chemicals, which make them unsuitable for biological applications.
In a new study, researchers have successfully tattooed tardigrades using ice lithography, as detailed in a recent Nano Letters study.
Tardigrades can withstand extreme conditions in their cryptobiotic state, making them the perfect candidates for this microfabrication experiment. Researchers first coated them with a thin layer of ice and then used an electron beam to carve patterns into them. As the ice sublimated, the imprint remained on the creature’s surface.
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To tattoo a tardigrade, researchers first place it into cryptobiosis, a state of extreme dehydration that causes it to enter suspended animation. They then put the tardigrade on carbon-composite paper, cooling it to -226°F (-143°C) before covering it with anisole, an organic compound with a scent similar to anise.
The frozen anisole acted as a protective layer, shielding the tardigrade’s surface from the focused electron beam as researchers etched microscopic patterns onto it.
When exposed to the electron beam, anisole reacted and formed a biocompatible chemical that stuck to the tardigrade’s surface. As the creature warmed up, any unreacted anisole disappeared, leaving behind the tattooed pattern. Once researchers rehydrated the tardigrade, it came back to life, now marked with a design.
This method enabled researchers to create intricate patterns, including squares, dots, and even a university logo, with lines as narrow as 72 nanometers wide.
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Approximately 40% of the tardigrades survived, and researchers believe the success rate could be improved with further refinements. Most importantly, the tardigrades showed no changes in behavior, suggesting that the technique is safe and could help print microelectronics or sensors onto living tissue.
Journal Reference:
- Zhirong Yang et al., Patterning on Living Tardigrades, Nano Letters (2025). DOI: 10.1021/acs.nanolett.5c00378
