A UV-light-controlled bioinspired adhesive could have applications in fields ranging from robotics to medical technology. Users can turn the substance’s stickiness on and off remotely and it leaves no residues on surfaces.

A gecko foot.The research team from Kiel University in Germany drew inspiration from the gecko and other animals that can walk upside down. Their sticking mechanisms have to be reversible and leave no footprints behind. Typically, these mechanisms respond to a muscle stimulus.

The researchers chose to use light as the stimulus to turn their adhesive on and off. They first developed an elastic porous material (LCE, liquid crystal elastomer) that bends when illuminated with UV light to use as the new adhesive’s base. Bending caused by light stimulation causes the material to “let go” of the substrate. More intense light caused greater bending.

The bioinspired photocontrollable microstructured transport device (BIPMTD) sandwiches a layer of LCE film between layers of polydimethylsiloxane (PDMS). The surface layer contains mushroom-shaped adhesive microstructures protruding from the PDMS, giving it good adhesion, the researchers say. The backing layer seals the LCE film between the two PDMS layers.

The team demonstrated how the new material can transport objects. By turning the UV light off and on, the substance would attach itself to the test objects, a glass sphere and a circular glass slide, and move the objects across the adhesive surface. The substance regains its original configuration when light is removed.

The team envisions using their adhesive in industrial pick-and-drop systems and for industrial micromanipulation tools.