Adhesive mechanisms in the natural world, as used by geckos and other animals when they walk upside down on the ceiling, have many advantages: they are always strongly adhesive - and without any glues or residues. Scientists at Kiel University are researching how these mechanisms can be artificially created. An interdisciplinary research team from Materials Science, Chemistry and Biology has now succeeded in developing a bioinspired adhesive material that can be controlled remotely by using UV light. This way it is possible to precisely transport objects in a micro-range. The findings could be interesting for applications in the fields of robotics, industry and medical technology.
In nature, mechanical stimuli such as muscle movements ensure that animals’ legs adhere to surfaces and can be detached again. The scientists in Kiel are using light to control their artificial adhesive mechanism instead, which they have built inspired by models from nature.
When illuminated with UV light, the intelligent material with the adhesive surface can transport three-dimensional objects (here, a 1 millimetre diameter glass sphere).
“The advantage of light is that it can be used very precisely. It is reversible, so it can be switched on and off again, and that very quickly,” says Emre Kizilkan from the Functional Morphology and Biomechanics research group under Professor Stanislav Gorb at the Zoological Institute. The Kiel-based research team's results were published in the current edition of the scientific journal Science Robotics.
So the scientists first developed an elastic porous material (LCE, liquid crystal elastomer) which bends when illuminated with UV light, on account of its special molecular structure. When doing so, they noticed that the more porous the material, the more it bents.
The researchers made use of this fact. “Due to their structures, porous materials can be very easily incorporated to other materials,” explains Kizilkan. “So we tested what happens when we combined the elastic material, which reacts well to light, with a bioinspired material that has good adhesive properties.”
The result is an intelligent, adhesive composite material that can be controlled with light. The surface consists of mushroom-shaped adhesive microstructures, as can be found on the feet of some species of beetles. Flat or three-dimensional small elements such as microscope slides or glass spheres can attach and be picked up. When the composite material is illuminated with UV light, it bends. Because of the bending of the surface more and more adhesive elements detach from the object, until it can finally be dropped down again.
“We were able to show that our new material can be used to transport objects. Moreover, we demonstrated that the transport can be controlled very precisely with light – on a micro-level,” explains Kizilkan. Gorb adds: „We use light as a remote control, so to say. Our bioinspired adhesive material doesn’t leave any residues on the objects, either.”
The research group’s discovery is therefore especially interesting when building sensitive sensors or micro computer chips. They need to be manufactured in an environment that is protected from external influences and impurities, such as Kiel University’s cleanroom. “In the long term, we would like to use the new material to develop micro-robots which can be controlled by light to move forwards and climb walls,” is Professor Gorb’s insight.
The research project is part of the Collaborative Research Centre (SFB) 677 “Function by Switching” at Kiel University, in which 100 scientists from Chemistry, Physics, Materials Science, Pharmacy and Medicine are working on a cross-disciplinary basis to develop switchable molecular machines which can be controlled by light, for example.
Science Robotics: E. Kizilkan, J. Strueben, A. Staubitz, S. N. Gorb, Bioinspired photocontrollable microstructured transport device. Sci. Robot. 2, eaak9454 (2017). http://robotics.sciencemag.org/content/2/2/eaak9454; DOI: 10.1126/scirobotics.aak9454
Royal Society Open Science: E. Kizilkan, J. Strueben, X. Jin, C. F. Schaber, R. Adelung, A. Staubitz, S. N. Gorb, Influence of the porosity on the photoresponse of a liquid crystal elastomer. R. Soc. Open Sci. 3, 150700 (2016). DOI:10.1098/rsos.150700
Photos are available for download under:
When illuminated with UV light, the intelligent material with the adhesive surface bends. This way it can lift, transport and put down flat and three-dimensional objects (here, a 1 millimetre diameter glass ball).
Photo/Copyright: Emre Kizilkan
The new composite material consists of two substances: an adhesive material (blue) and an elastic LCE (liquid crystal elastomer) plastic (yellow). LCE is made up of azobenzene molecules which bend - thus bending the whole material - when they are irradiated with UV light. The curvature causes the adhesive elements to detach from the object.
Image/Copyright: Emre Kizilkan and Jan Strüben
The second, adhesive material is a polymer modelled on examples from nature. Its surface consists of a mushroom-shaped microstructure which becomes visible under the scanning electron microscope. It is recreated with highly adhesive, reversible adhesive elements, as can be found in some species of beetle.
Photo/Copyright: Emre Kizilkan
Precisely controlling micro-transportation using light: the new composite material (BIPMTD) adheres when laid on a glass slide (i). The glass slide can thus be picked up (ii). When UV light with a wavelength of 365 nanometres is switched on (iii), the glass slide detaches itself in 5 seconds and can be put down (iv).
Photo/Copyright: Emre Kizilkan
Materials scientist Emre Kizilkan tests how strongly the composite material adheres to objects when illuminated with UV light, using an experimental set-up for measuring strength.
Photo/Copyright: CAU/Julia Siekmann
Professor Stanislav N. Gorb
Zoological Institute at Kiel University
Tel.: +49 (0)431/880 -4513
Tel.: +49 (0)431/880-4859
http://robotics.sciencemag.org/content/robotics/suppl/2017/01/10/2.2.eaak9454.DC... The video shows how the composite material picks up a glass ball with a diameter of 1 millimetre, transports it and puts it down again when illuminated with UV light.
http://Copyright: Emre Kizilkan
Dr. Boris Pawlowski | Christian-Albrechts-Universität zu Kiel
Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University
Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences