3D topographic reconstruction of CLSM image showing bacterial microcolonies encapsulated in EPS forming a thick biofilm on whisker with scattered patches of microcolonies on (stained green with B-35000, Backlight green live bacterial stain).

<p>Right panel depicts box and whisker diagram of bacterial biovolume of three samples. A box represents 25^th to 75^th percentile range, intersected by median line. Whiskers extend above and below the box range, indicating highest to lowest values.</p

SEM micrograph showing bacterial interactions with whiskers and mechanical injury.

<p>(A-C) Low and high magnification SEM images showing whiskers piercing through the bacterial membrane on Cu whiskers (red versus white arrow exhibit low and high magnification scanned images at tilted angle. (D-F) Bacterial cluster “pinning” on high-aspect-ratio Au-coated Cu whiskers (white arrows in 4A). Red show a high aspect ratio piercing through many bacterial cell membrane at low (4B) and high magnification (4C). Insert in Fig 4B illustrates microcolonies pinned at whisker bottom.</p

Microscopic examinations of Cu and Au-coated Cu whiskers.

<p>(A-C) Transmission electron microscopy micrograph (A), diffraction pattern (B) and energy dispersive x-ray analysis showing material properties of Cu whiskers (C). (D-E) Low and high magnification view of Cu nanowhiskers. (F-H) SEM micrograph at a tilted angle showing high aspect ratio Cu whiskers. (I-J). Deconvoluted XPS spectra showing the elemental composition of Cu and oxygen of nanowhiskers.</p

XPS surface composition and elemental analysis of Cu and Au-shelled Cu whiskers.

<p>XPS surface composition and elemental analysis of Cu and Au-shelled Cu whiskers.</p

Physicochemical and bacterial adhesion response on different nanowhisker samples.

<p>Physicochemical and bacterial adhesion response on different nanowhisker samples.</p

Comparison of wettability analysis of Cu whiskers versus control flat Cu thin films.

<p>Dynamic contact angle hysteresis (CAH) analysis via advancing (A-C) versus receding (D-F) contact angle of whisker and flat samples. (G-I) Mean contact versus step number surface profiles of whisker against the control flat surfaces.</p

Qualitative and quantitative characterization of surface topography with laser scanning microscopy.

<p>Optical, height and 3D topography of Au-coated Cu nanowhiskers (A-C), Cu whiskers (D-F) and flat Cu surfaces (G-I).</p

Reliability of Single Crystal Silver Nanowire-Based Systems: Stress Assisted Instabilities

Time-dependent mechanical characterization of nanowires is critical to understand their long-term reliability in applications, such as flexible-electronics and touch screens. It is also of great importance to develop a theoretical framework for experimentation and analysis on the mechanics of nanowires under time-dependent loading conditions, such as stress-relaxation and fatigue. Here, we combine <i>in situ</i> scanning electron microscope (SEM)/transmission electron microscope (TEM) tests with atomistic and phase-field simulations to understand the deformation mechanisms of single crystal silver nanowires held under constant strain. We observe that the nanowires initially undergo stress-relaxation, where the stress reduces with time and saturates after some time period. The stress-relaxation process occurs due to the formation of few dislocations and stacking faults. Remarkably, after a few hours the nanowires rupture suddenly. The reason for this abrupt failure of the nanowire was identified as stress-assisted diffusion, using phase-field simulations. Under a large applied strain, diffusion leads to the amplification of nanowire surface perturbation at long wavelengths and the nanowire fails at the stress-concentrated thin cross-sectional regions. An analytical analysis on the competition between the elastic energy and the surface energy predicts a longer time to failure for thicker nanowires than thinner ones, consistent with our experimental observations. The measured time to failure of nanowires under cyclic loading conditions can also be explained in terms of this mechanism

Reliability of Single Crystal Silver Nanowire-Based Systems: Stress Assisted Instabilities

Time-dependent mechanical characterization of nanowires is critical to understand their long-term reliability in applications, such as flexible-electronics and touch screens. It is also of great importance to develop a theoretical framework for experimentation and analysis on the mechanics of nanowires under time-dependent loading conditions, such as stress-relaxation and fatigue. Here, we combine <i>in situ</i> scanning electron microscope (SEM)/transmission electron microscope (TEM) tests with atomistic and phase-field simulations to understand the deformation mechanisms of single crystal silver nanowires held under constant strain. We observe that the nanowires initially undergo stress-relaxation, where the stress reduces with time and saturates after some time period. The stress-relaxation process occurs due to the formation of few dislocations and stacking faults. Remarkably, after a few hours the nanowires rupture suddenly. The reason for this abrupt failure of the nanowire was identified as stress-assisted diffusion, using phase-field simulations. Under a large applied strain, diffusion leads to the amplification of nanowire surface perturbation at long wavelengths and the nanowire fails at the stress-concentrated thin cross-sectional regions. An analytical analysis on the competition between the elastic energy and the surface energy predicts a longer time to failure for thicker nanowires than thinner ones, consistent with our experimental observations. The measured time to failure of nanowires under cyclic loading conditions can also be explained in terms of this mechanism

Niobium as Alternative Material for Refractory and Active Plasmonics

The development of stable compounds for durable optics is crucial for the future of plasmonic applications. Even though niobium is mainly known as a superconducting material, it can qualify as an alternative material for high-temperature and active plasmonic applications. We utilize electron beam lithography combined with plasma etching techniques to fabricate nanoantenna arrays of niobium. Tailoring the niobium antenna geometry enables precise tuning of the plasmon resonances from the near- to the mid-infrared spectral range. Additionally, the hydrogen absorptivity as well as the high-temperature stability of the antennas have been investigated. Further advantages of niobium such as superconductivity make niobium highly attractive for a multitude of plasmonic devices ranging from active and refractory perfect absorbers/emitters to plasmon-based single photon detectors