Nanoparticle-Modified Electrode with Size- and Shape-Dependent Electrocatalytic Activities

The size, shape, composition, and crystalline structures of noble metal nanoparticles are the key parameters in determining their electrocatalytic performance. Here, we report on a robust chemical-tethering approach to immobilizing gold nanoparticles onto transparent indium tin oxide (ITO) glass electrode surfaces to systematically investigate their size- and shape-dependent electrocatalysis toward a methanol oxidation reaction (MOR) and an oxygen reduction reaction (ORR). Monodisperse 20 nm nanospheres (NS20s), 45 nm nanospheres (NS45s), and 20 nm × 63 nm nanorods (NRs), which could be chemically tethered to ITO-surface-forming submonolayers without any aggregation, were synthesized. These nanoparticle-modified ITO electrodes exhibited strong electrocatalytic activities toward MOR and ORR, but their mass current densities were highly dependent on the particle sizes and shapes. For particles with similar shapes, the size determined the mass current densities: smaller particle sizes led to greater catalytic current densities per unit mass because of the greater surface-to-volume ratio (NS20s > NS45s). For particles with comparable sizes, the shape or crystalline structure governed the selectivity of the electrocatalytic reactions: NS45 exhibited a higher mass current density in MOR than did NRs because its dominant (111) facets were exposed, whereas NRs exhibited a higher mass current density in ORR because its dominant (100) facets were exposed

Copper Nanowires as Conductive Ink for Low-Cost Draw-On Electronics

This work tackles the complicated problem of clump formation and entanglement of high aspect ratio copper nanowires, due to which a well dispersed solution for use as a true ink for drawable electronics has not been made until now. Through rheology studies even a hard to use material like copper nanowires was tailored to be made into a highly efficient conductive ink with only 2 vol % or 18.28 wt % loading which is far lower than existing nanoparticle based inks. This versatile ink can be applied onto various substrates such as paper, PET, PDMS and latex. By using the ink in a roller ball pen, a bending sensor device was simply drawn on paper, which demonstrated detection of various degrees of convex bending and was highly durable as shown in the 10 000 bending cycling test. A highly sensitive strain sensor which has a maximum gauge factor of 54.38 was also fabricated by simply painting the ink onto latex rubber strip using a paintbrush. Finally a complex conductive pattern depicting the Sydney Opera House was painted on paper to demonstrate the versatility and robustness of the ink. The use of Cu NWs is highly economical in terms of the conductive filler loading in the ink and the cost of copper itself as compared to other metal NPs, CNT, and graphene-based inks. The demonstrated e-ink, devices, and facile device fabrication methods push the field one step closer to truly creating cheap and highly reliable skin like devices “on the fly”

Self-Assembled Nanocube-Based Plasmene Nanosheets as Soft Surface-Enhanced Raman Scattering Substrates toward Direct Quantitative Drug Identification on Surfaces

We report on self-assembled nanocube-based plasmene nanosheets as new surface-enhanced Raman scattering (SERS) substrates toward direct identification of a trace amount of drugs sitting on topologically complex real-world surfaces. The uniform nanocube arrays (superlattices) led to low spatial SERS signal variances (∼2%). Unlike conventional SERS substrates which are based on rigid nanostructured metals, our plasmene nanosheets are mechanically soft and optically semitransparent, enabling conformal attachment to real-world solid surfaces such as banknotes for direct SERS identification of drugs. Our plasmene nanosheets were able to detect benzocaine overdose down to a parts-per-billion (ppb) level with an excellent linear relationship (<i>R</i>² > 0.99) between characteristic peak intensity and concentration. On banknote surfaces, a detection limit of ∼0.9 × 10^–6 g/cm² benzocaine could be achieved. Furthermore, a few other drugs could also be identified, even in their binary mixtures with our plasmene nanosheets. Our experimental results clearly show that our plasmene sheets represent a new class of unique SERS substrates, potentially serving as a versatile platform for real-world forensic drug identification

VSP-ADV feature ratings.

<p>Ratings of the different features part of VSP-ADV.</p

VSP-ADV sitting posture charts: Time lines.

<p>A high-resolution image of all postures with a duration <i>d</i> > 10 <i>sec</i>. ordered by starting time. Working day-specific sitting posture patterns can be evaluated. See Fig 10 for posture X labels.</p

VSP-ADV sitting posture charts: Posture patterns.

<p>A high-resolution image of all postures with a duration <i>d</i> > 10 <i>sec</i>. ordered by pose duration. Subject-specific sitting posture patterns can be evaluated.</p

Virtual-Spine: Real-time monitoring and visualization system.

<p>The Real-time Monitoring System: a) in combination with a conventional office chair showing the VSP back and seat mats attached with sensors; b) the connecting hardware of the VSP mat to the computer system; The Real-time Visualization System: c) a laptop running the posture recognition system (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195670#pone.0195670.g004" target="_blank">Fig 4</a>).</p

VSP personal sitting behavior.

<p>Personal Rating, Global Rating, First Changes, Sitting Behavior rating before and after the study.</p

VSP-ADV sitting health posture charts: Time lines.

<p>A high-resolution image of all postures with a duration <i>d</i> > 10 <i>sec</i>. ordered by starting time. The duration-related rating is shown here. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195670#pone.0195670.g008" target="_blank">Fig 8</a> for time X labels.</p

Virtual-Spine system overview.

<p>Left: VSP-RTM: Real-Time Monitoring system; Center: VSP-RTV: Real-Time Visualization system; Right: VSP-ADV: Accumulated Data Visualization system.</p