Watch This Hydrogel Strut Across A Table

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Caroline Reid

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1835 Watch This Hydrogel Strut Across A Table
Screenshot from video of walking hydrogel. Kim et al./Nature Materials

When things heat up, this L-shaped object puts its best foot forward. This innovative hydrogel has an interesting property: When surrounded by temperature changes, it does a good attempt at the cha-cha slide. 

Under normal circumstances, hydrogels change their shape by absorbing water and releasing it again. However, this version is a little different. Scientists from the University of Tokyo have designed a gel that expands and contracts alongside temperature changes, completely bypassing the need for water intake – a feature that unlocks a lot of possibilities for potential applications.


The gel is composed of thin layers of parallel sheets that have a charge. At room temperature, these sheets are quite content to sit next to each other. As the gel heats up, from 25°C (77°F) to 45°C (113°F), these parallel sheets become more repulsive and start to inch away from each other. This causes the gel to expand and prompts the front 'foot' of the L-shaped hydrogel to take a small step forward. 

As the temperature decreases back to room temperature, the layers become less repellent and return to their original positions. This makes the front 'foot' of the gel contract, effectively dragging its back foot forward. As the temperature fluctuations increase, the gel travels across the surface. The results are published in Nature Materials.

So far, the team has used this gel to create shapes – this includes the walking piece of polymer and a square that expands to a rectangle. There are many more possible shapes to explore. 

One exciting avenue to pursue could be its potential energy-saving or safety applications. Home radiators could be fitted with one of these gels to automatically seal a valve when the radiator reaches the perfect temperature, thus saving energy. The material could also have possible safety applications in factories where overheating vents or pipes could be managed automatically with this humble hydrogel.


You can watch the gel stride along here:



[H/T: New Scientist]


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