Researchers have successfully developed a method to “tattoo” microscopic tardigrades, marking a significant advance in nanotechnology. This breakthrough has the potential to pave the way for the creation of biocompatible nanoscale devices, including sensors, integrated circuits, and even living robots.
The goal of this research is not merely to decorate the hardy tardigrades, but to explore how nanoscale patterns can be applied to living organisms. This process also provides new insights into the resilience of tardigrades, some of which survived the procedure and continued to move around, adorned with intricate patterns.
Ding Zhao, an optical engineer from the Technical University of Denmark, explained, “Through this technology, we’re not just creating micro-tattoos on tardigrades, we’re extending this capability to various living organisms, including bacteria.”
The ability to etch precise patterns onto tiny surfaces is a crucial challenge in the field of nanotechnology. While progress has been made in adapting existing technologies to the nanoscale for material engineering, creating high-resolution patterns on living organisms has proven to be much more complex.
To achieve the tattoos, Zhao and his team adapted a nanofabrication technique known as ice lithography. This method, a form of electron-beam lithography, uses an electron beam to etch nanoscale patterns onto surfaces. However, traditional electron-beam lithography can introduce contamination or damage to very fine surfaces. The team discovered that applying a thin layer of ice between the beam and the target prevented such issues, allowing them to create patterns as small as 20 nanometers.
For context, the average width of a human hair ranges from 80,000 to 100,000 nanometers, while tardigrades can be up to 500,000 nanometers in size.
Tardigrades are renowned for their extreme durability, largely due to their ability to enter a state of cryptobiosis. When faced with harsh environmental conditions, tardigrades dehydrate and suspend their metabolism, allowing them to survive freezing, boiling, and even the vacuum of space. Zhao’s team took advantage of this by inducing the cryptobiosis state in the tardigrades before subjecting them to the electron beam.
Each tardigrade was processed individually to minimize exposure to the experimental conditions. The creatures were placed on a sheet of carbon-composite paper within a vacuum chamber, which was then cooled to -143°C (-226°F). Anisole, a colorless liquid compound, was applied over the cooled tardigrade to protect it from the electron beam. When the beam was directed at the specimen, the anisole reacted and formed a new compound, which adhered to the surface of the tardigrade, leaving behind a nanoscale pattern.
Once the tardigrade was rehydrated, the pattern remained intact, with details as small as 72 nanometers. The team then tested the creatures’ ability to survive the procedure by rehydrating them and attempting to revive them.
“This study successfully demonstrates in situ fabrication of micro/nanopatterns on living organisms using ice lithography,” the researchers noted in their published paper.
While tardigrades are uniquely suited to endure such processes, the study marks just the beginning of this line of research. The team hopes to refine the technique to improve the survival rate of other organisms that may not have the same level of resilience.
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