Gold Layers on Elastomers near the Critical Stress Regime

This study demonstrates that the interplay between functionalized oxygen-plasmatreated polydimethylsiloxane (PDMS) films and sputter-deposited metal electrodes allows for conserving compressive stress within the electrode. Insulator–metal transition already occurs for 10 nm thin Au electrodes, and below this electrode thickness, atomic force microscopy nanoindentations with sub-micrometer resolutions reveal no stiffening of the Au/PDMS heterostructure.

Adv. Mater. Technol., 2017, 2

Bekim Osmani, Hans Deyhle, Tino Töpper, Thomas Pfohl, Bert Müller

Soft electrodes are essential components of soft robotics, tunable optics, microfluidics, flexible electronics, neuroprosthetics, and dielectric elastomeric transducers (DET). The two main paths employed to increase an electrode’s compliance involve the manipulation of either its intrinsic material properties or its structural features, such as the introduction of wrinkles, which arise above the critical stress of metal films on elastomeric substrates. Herein, this study demonstrates that the interplay between functionalized oxygen-plasmatreated polydimethylsiloxane (PDMS) films and sputter-deposited metal electrodes allows for conserving compressive stress within the electrode. Insulator–metal transition already occurs for 10 nm thin Au electrodes, and below this electrode thickness, atomic force microscopy nanoindentations with sub-micrometer resolutions reveal no stiffening of the Au/PDMS heterostructure. These DETs exhibit reduced electrocreasing, which is a significant contributor to structural failure, while their enhanced dielectric breakdown field of up to 120 V μm–1 enables calculated strains above 10% — a crucial requirement for thin-film DETs such as those used for artificial muscles.

AFM images were acquired by raster scanning the region of interest with a soft AFM probe (Tap190Al-G probe) in tapping mode on a Nanosurf FlexAFM.

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Flex-Axiom — AFM for materials research

By advancing key technologies and designs, Nanosurf has made the Flex-Axiom one of the most versatile and flexible atomic force microscopes ever, allowing a large variety of materials research applications to be handled with ease. Together with the powerful C3000 controller, complex material characterizations are possible.

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Flex-Bio — AFM for biology and life science

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