Using an experimental technique called ice lithography, a team of researchers successfully etched nanoscale patterns onto living tardigrades. Not all of them survived, unfortunately; but some of them did. Their breakthrough, published in Nano Letters, could pave the way for a new generation of living microrobots and biocompatible sensors.
“Through this technology, we’re not just creating micro-tattoos on tardigrades — we’re extending this capability to various living organisms, including bacteria,” explains Ding Zhao, a co-author of the paper.
This tardigrade is sporting a new “tattoo” — represented in this magnified image by the highlighted dots, and visible in the inset image. Image credits: Nano Letters 2025, DOI: 10.1021/acs.nanolett.5c00378
How do you tattoo a tardigrade?
The process began by coaxing tardigrades into their “tun” state. In this state, which tardigrades use to withstand extreme environmental conditions, they expel almost all the water from their body. They retract their limbs, and curl into a lifeless-looking ball called a “tun”. This allows them to survive for years without food, water or even oxygen.
Once the water bears were desiccated and immobilized, the scientists laid each onto carbon-composite paper inside a vacuum chamber chilled to -226 degrees Fahrenheit (-143 degrees Celsius). They then sprayed a thin layer of anisole — a chemical compound that smells like licorice, on the creatures. Then, using an electron beam, researchers “wrote” onto the anisole layer.
Where the beam hit, the anisole reacted and stuck to the tardigrade’s surface. As the animals warmed under vacuum, the unreacted anisole sublimated, leaving only the etched design behind.
With this approach, researchers inscribed patterns as fine as 72 nanometers wide, a thousand times thinner than a human hair. They successfully drew squares, dots, lines, and even a university logo.
A simplified representation of the tattooing process. Image credits: Zhao et al., Nano Letters.
Forty percent of the tattooed tardigrades survived the ordeal, reviving with no apparent behavioral changes. Their new tattoos stayed intact even after stretching, rinsing, and drying. While 40% survival isn’t ideal, Zhao’s team believes refinements to the technique could increase that number and make it safe.
Why this matters
This experiment isn’t just about tattooing tiny animals for fun. It addresses a critical challenge in bioengineering: how to integrate the precision of microfabrication with the delicate nature of living organisms.
Traditional microfabrication revolutionized fields like electronics and photonics. But it’s one thing to tattoo on a static material and it’s another to do it on living tissues. High-energy beams, toxic chemicals, and rigid coatings typically damage living tissue. Ice lithography, developed a few years ago by other researchers, originally by Gavin King (who was not involved in the study), offers a gentler alternative. “It is challenging to pattern living matter, and this advance portends a new generation of biomaterial devices and biophysical sensors that were previously only present in science fiction,” King said.
Living microrobots — part biological, part engineered — could become game-changers for medicine. Imagine microbial cyborgs designed to monitor environments inside the human body, deliver drugs precisely where needed, or even repair tissues from within.
For now, the team’s accomplishment stands as both a technical and biological milestone: proof that the most indestructible creatures on Earth can become canvases for the future of nanotechnology. It’s still early days. But the study also opens new possibilities in cryopreservation and astrobiology, fields that already look to tardigrades as models for extreme survival.
