Biologically inspired frictional and adhesive artificial surfaces derived from hierarchically ordered patterns of carbon nanotubes

• Applicant: Professor Dr. Jörg J. Schneider
• Subject Area: Synthesis and Properties of Functional Materials ; Biomaterials
• Term: from 2009 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 156714784

The planned project will study natural and artificial systems which use biomechanical properties to increase contact forces (adhesion, friction) for reversible attachment to a substrat or for sliding prevention in contact. Within the project there are two central tasks which are strongly interconnected to each other.One task is to investigate the ultrastructure, material properties, and attachment-detachment performances in hairy attachment devices of insects, spiders, and geckos, the other task is to build artificial structures based on carbon nanotubes (CNTs). From the materials science point of view, carbon nanotubes are one of the most promising approaches to mimic hierarchical micro- and nanostructures closely resembling the gecko toe structure. These laboratory made structures will be designed in our project in a way that they mimic morphology and some properties of their natural archetype, the setae of gecko. Synthetic ways for their production and routes to align them in a highly integrated manner are established in our labs.Two main research areas, (i) studies towards the biological ultrastructure, the mechanical properties of the attachment devices of insects and gecko setae as well as (ii) the synthesis, structuring, further chemical modification and experimental strength studies related to the adhesive and frictional properties of aligned hierachically ordered CNTs are the joint research endeavour. CNT surfaces will be experimentally tested by various force measurement techniques and the data will be compared and optimized towards those obtained on the biological systems. This approach will not only aid in outlining general rules of the interrelationship between the structure and function in biological systems, but will also allow for new insights into fundamental material properties of aligned CNT structures on their hierachical length scales. Such studies will certainly pave the way to development novel artifical surfaces with particular frictional and adhesive properties.The fundamental results of the planned cooperative project may have potential practical impact for manipulating submicron parts or devices. Often fine details can dramatically improve the performance of a technological system. From studies of biological systems we can learn, which features of natural systems (dimension and density, hair aspect ratio, slope, hierarchy, shape of the contact, asymmetry of hair design combined with proper movements during attachment and detachment, use of gradient materials) are essential for optimal performance of the system on a variety of surfaces. Most of these parameters can be varied when using CNTs as artificial materials basis for self adhesive surface structures. Such structures are of interest in dry adhesion which may be used in reversible gluing, or in pick and place technologies for mounting or manipulating microstructured or even nanostructured pieces in technologically important areas. This area of bionics has been only barely touched so far.

• DFG Programme: Research Grants