Sites on poly(dimethylsiloxane) are selected by ultraviolet exposure. In a subsequent electroless deposition, solid silver films are created on the selected sites only. In this way, facile vacuum-free deposition of electrodes from the liquid phase and their photoresist- and solvent-free patterning are realized. The technique enables reliable rigid-to-soft interconnects that are reversibly stretchable under arbitrary and changing stretching directions.

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Stretchable large area electronics conform to arbitrarily-shaped 3D surfaces and enables comfortable contact to the human skin and other biological tissue. There are approaches allowing for large area thin films to be stretched by tens of percent without cracking. The approach presented here does not prevent cracking, rather it aims to precisely control the crack positions and their orientation. For this purpose, the polydimethylsiloxane (PDMS) is hardened by exposure to ultraviolet radiation (172 nm) through an exposure mask. Only well-defined patterns are kept untreated. With these soft islands cracks at the hardened surface can be controlled in terms of starting position, direction and end position. This approach is first investigated at the hardened PDMS surface itself. It is then applied to conductive silver films deposited from the liquid phase. It is found that statistical (uncontrolled) cracking of the silver films can be avoided at strain below 35%. This enables metal interconnects to be integrated into stretchable networks. The combination of controlled cracks with wrinkling enables interconnects that are stretchable in arbitrary and changing directions. The deposition and patterning does not involve vacuum processing, photolithography, or solvents.

also drawn enormous attention due to their highly tunable electromagnetic proper ties over a broad range of frequencies and novel fields of research such as flatland optics, hyperlenses, and nanoscopic phase manipulation [7][8][9][10][11][12][13][14][15] Especially plasmonic metasurfaces benefit from extraordinary high field intensities, enabling improved absorption of electromagnetic radiation at visible and infrared wavelengths. [16][17][18][19][20] Providing high electrical with thermal con ductivity, plasmonic metamaterial absorbers are therefore promising for various appli cations such as solar energy harves ting, [21,22] heat management, [18] electro thermal systems, [23] sensors [5,17,24] as well as nonlinear optics, [25] and could also serve as electrodes and heat sinks at the same time.In order to achieve absorption in plas monic metasurface-based systems, several methods have been developed. Many of them rely on expensive bottomup processes or need relatively large amounts of metal and/or strongly roughened surfaces in order to obtain broadband absorption. [26][27][28] On the other hand, highly absorbing systems with low material consumption have been realized using dielectric films in order to build metal-insu lator-metal (MIM) absorbers. [9,29,30] Further on, recent MIM absorbers are compatible with costefficient statistical large scale production methods. [31][32][33][34] However, due to the dielectric films, the electrical and thermal conductivity of MIM absorbers are not ideal. If the functionality of MIM absorbers could be preserved without any dielectrics, highly conductive broadband absorbers on large scales with low production costs would be achieved.We present a novel metasurface consisting of only silver, demonstrating the resonant nature of MIM absorbers without the necessity of any insulating spacer material. The technique is performed by polydimethylsiloxane (PDMS)assisted transfer printing of silver nanoparticles (AgNP) directly on top of a thin continuous silver (Ag) film, thus forming a metasurface. In addition to that, the technique can easily be used for costefficient, largearea fabrication on arbitrary substrates. The development of the metasurface is based on the experimental observation, that the absorption of AgNP films on PDMS is significantly enhanced, when they are brought into contact with a silver thin film. Results and Discussion Preliminary Simulation of Simplified GeometriesWe first study this phenomenon with numerical simula tions, whereby AgNPs are approximated by perfect silver In various applications simultaneous large optical absorption and large thermal and electrical conductivity are desired. As bulk materials cannot fulfill that need, metamaterials have been developed that often require complicated nanotechnology. The work presents the facile fabrication of black metasurfaces consisting of silver only. Silver nanoparticles (AgNPs) are transfer printed onto a silver film from a polydimethylsiloxane (PDMS) stamp. Numerical simulations confirm that gap plasmon modes b...