This study explores a number of low-viscosity glass-forming polymers for their suitability as high-speed materials in electrohydrodynamic (EHD) lithography. The use of low-viscosity polymer films significantly reduces the patterning time (to below 10 s) compared to earlier approaches, without compromising the high fidelity of the replicated structures. The rapid pace of this process requires a method to monitor the completion of EHD pattern formation. To this end, the leakage current across the device is monitored and the sigmoidal shape of the current curve is correlated with the various stages of EHD pattern formation.

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Natural adhesive systems, consisting of pads covered by dense assemblies of high aspect ratio branched adhesive setae, ( Figure 1 a) excel in terms of adhesive strength on nearly any surface. Facile contact release is achieved by spatulae at the seta tips that are inclined with respect to the setae axis, requiring a normal preload and shear to establish adhesive contact and enabling low-resistance contact release by peel-off. While technologically valuable, dense hierarchical fi brillar adhesives are diffi cult to manufacture and no scalable approaches yet exist to create the required spatulae asymmetry. Here we demonstrate the manufacture of biomimetic hierarchical nanostructures based on polymer micro-pillar arrays topped with densely packed, vertically aligned carbon nanotubes (CNTs), which closely resemble gecko toe-pads. A permanent spatula-like asymmetry is introduced into the CNT assembly during a fi rst adhesion-release cycle consisting of a normal preload and a shear motion. The shear adhesion forces of these deformed hierarchical CNTs/ polymer pillar arrays on smooth and rough surfaces were found to be considerably higher than those of non-structured (i.e., plain) CNT forests, caused by the conformal attachment of the multilevel adhesive elements to the coarse surface topography, energy dissipation during the deformation of the polymer pillars and the increased contact area provided by the inclined CNTs.Exploitation of the naturally optimized design principles of controllable attachment found in biological systems is highly desirable for synthetic adhesives. If successful, such sophisticated biomimetic adhesives would enable a new platform for a variety of applications, ranging from the micromanipulation in production processes, to microelectronics, robotics and biomedicine. Strong, rapid and robust adhesion mediated by gecko toe pads relies on the conformal contact of a fi nely structured adhesive area to any surface profi le, while maintaining structural integrity and wear-resistance. [1][2][3] While highly effi cient in a large number of biological organisms, the biomimetic replication of the "gecko effect" is diffi cult because of the complex geometry of the adhesive surface and its required hierarchical structure.The toe-pads of geckos consist of millions of branched adhesive setae (Figure 1 a), which are arranged in a grid-like pattern on the ventral surface of each scansor, branching out into hundreds of nanometer-sized spatular tips (ca. 200 nm wide), allowing them to deform and adhere to nearly any surface. [ 4 ] Gecko toe-pads consist of β -keratin (elastic modulus E = 1-3 GPa). [ 5,6 ] The intimate contact with surfaces of any roughness [ 7,8 ] gives rise to signifi cant van der Waals (vdW) forces, [ 9 ] and their asymmetric structure allows controlled attachment and detachment during locomotion. [ 10,11 ] Although considerable progress has been made in mimicking fi brillar adhesives by utilizing nanofabrication routes including photo and electron-beam lithography, [12][13][14] micro molding...