Image: The arms of the tetrapod crystal staples interlock with each other forming strong bonds. Image from scanning electron microscope © CAU Germany, Image © Xin Jin

In high technology businesses such as medical engineering, there is a strong demand for innovative ways to make polymers, particularly silicone, stick to other materials, for example to further develop breathing masks, implants or sensors. Medical applications require materials that are absolutely non-harmful, i.e. biocompatible. Many joining methods involve chemical reactions, which may change the polymers' properties and can cause injurious or even toxic effects on organisms. The tetrapod stapling, on the contrary, is a purely mechanical process. Therefore the Kiel team assumes it to be biocompatible. With the tetrapod staples, the scientists have achieved a stickiness – the so-called peel strength – of 200 Newtons per meter, which is similar to peeling sticky tape off glass.