If you're lifting a tiny, delicate object, you likely don't want to exert too much pinching pressure on it, nor do you want to leave it covered in sticky residue. That's why scientists at Germany's Kiel University have developed an adhesive material that not only doesn't leave residue, but that can also be remotely "turned on and off" via ultraviolet light.
At the heart of the material is a porous liquid crystal elastomer (LCE), that bends when exposed to UV light. This has been bonded to an existing adhesive polymer. Inspired by the gripping feet of insects, that polymer consists of microscopic mushroom-shaped structures that act like tiny suction cups.
When the resulting composite initially touches an object, the mushroom structures adhere to it, allowing it to be picked up. Once the object has been moved to the desired location, the material is then exposed to UV light. This causes the LCE in it to bend back – the more it bends, the greater the number of mushrooms that release their grip on the object, until it's been let go.
In the lab, the material has already been utilized to lift and move items such as microscope slides and glass spheres. Down the road, it is hoped that it could also be used for applications such as the manufacturing of highly-sensitive sensors or tiny computer chips. According to lead scientist Prof. Stanislav Gorb, it may even find use in "micro-robots which can be controlled by light to move forwards and climb walls."
A paper on the research was recently published in the journal Science Robotics.
Scientists at Germany's Leibniz Institute for New Materials have also created a switchable adhesive material, although theirs is switched on and off via an electrical signal.
Source: Kiel University