Researchers at Iowa State University have developed soft tentacles that can serve as the hands and fingers of robots, and they’re tiny. So tiny, in fact, that they work on the millimeter scale. The tentacles can gently hold an ant in place by wrapping around its thorax.

Most robots use two fingers to manipulate objects, which requires them to squeeze the fingers together, not unlike a human. However, for delicate objects, and especially at very small scales, such fingers can be damaging. The tentacles, developed by Jaeyoun Kim, In-Ho Cho, and Jungwook Paek, are capable of wrapping around an object without damaging it, inspired by tentacles in nature. Naturally occurring tentacles, the most famous of which are probably the eight arms of an octopus, allow creatures to manipulate objects safely, and part of the secret is that they’re soft.

The tentacles are made of PDMS, a transparent elastomer, which is formed into a very thin tube and capped at one end. But pumping air in and out of the tube, it can be made to coil around an object. Until now, tubes this small could only be made to bend once, which isn’t enough to truly hold an object. A combination of asymmetrical wall thickness within the tube and an extra lump of the material at the base allowed for the addition bend required for the spiral pattern.

A field called soft robotics seeks to build robots out of materials other than metal and hard plastics, and Kim and his co-authors combined those ideas with microrobotics, which is devoted to making smaller and smaller robots. The end result is a system by which very small robots can safely manipulate delicate objects, like the ant in the example above. In the future, such robots might be used in surgery, as they could grasp and move tissues or even blood vessels without damage.