Flexible highly conductive films based on expanded graphite /polymer nanocomposites

Highly electrically and thermally conducting films of expanded graphite/polymer nanocomposites were fabricated using an approach based on solution mixing methods. The use of Hydroxyethylcellulose and benzylic alcohol based solutions provides efficient dispersion and better exfoliation of multilayer graphene (nanographite) flakes that are further aligned in extended 2D layers forming continuous conductive pathways during lamination (hot calendering) process. Very high electrical conductivity (190 S/cm) was obtained for fabricated layered films. In contrast, for films produced by a conventional mixing and deposition method with acrylic copolymer and the same nanographitic material, with flakes randomly distributed within the composite, much lower conductivities (2.4 S/cm) were obtained

Graphite nanobelts characterization and application for blood pulse sensing

In this work, graphite nanobelts-based films as a promising material for applications in flexible blood pulse sensors with low power consumption are studied. A modified Langmuir Blodgett method used here for the sensor fabrication, is a reliable, simple and scalable technique allowing for controlled deposition of conducting films with desired electrical properties. The nanobelts, deposited over oxidized silicon or onto flexible polydimethylsiloxane substrates, were morphologically and electrically characterized. The response of the sensors to blood pulses measured on wrists and necks of two different persons (a male and a female) and the ways of the sensor response optimization are discussed

Graphite nanobelts characterization and application for blood pulse sensing★

In this work, graphite nanobelts-based films as a promising material for applications in flexible blood pulse sensors with low power consumption are studied. A modified Langmuir Blodgett method used here for the sensor fabrication, is a reliable, simple and scalable technique allowing for controlled deposition of conducting films with desired electrical properties. The nanobelts, deposited over oxidized silicon or onto flexible polydimethylsiloxane substrates, were morphologically and electrically characterized. The response of the sensors to blood pulses measured on wrists and necks of two different persons (a male and a female) and the ways of the sensor response optimization are discussed

Self-assembled nanostructures of 3D hierarchical faceted-iron oxide containing vertical carbon nanotubes on reduced graphene oxide hybrids for enhanced electromagnetic interface shielding

The self-assembled three dimensional (3D) hybrids nanostructure containing uniform growth of vertical carbon nanotubes (VCNTs) with faceted iron oxide nanoparticles (f-Fe3O4 NPs) on the surfaces of reduced graphene oxide nanosheets (rGO NSs) is achieved using microwave assisted approach. The formation of hierarchical 3D f-Fe3O4-VCNTs@rGO hybrids, using microwave method is a rapid, simple, and inexpensive synthetic route. First, the VCNTs grow with help of Fe NPs, and after oxidizing of Fe NPs in form of f-Fe3O4 NPs, the growth has terminated resulting in formation of small size (< 500 nm) VCNTs containing f-Fe3O4 NPs on its tip. The defect and oxygen-rich sites of rGO NSs favor the heterogeneous nucleation and growth of f-Fe3O4 NPs on the tip of VCNTs. The synthesized 3D f-Fe3O4-VCNTs@rGO hybrid shows the improved electromagnetic interference (EMI) for microwave shielding effectiveness (SE) as compared to both rGO NSs and Fe3O4 NPs@rGO NSs materials. This 3D f-Fe3O4-VCNTs@rGO hybrid demonstrates the shielding effectiveness value more than 25 dB as compared to Fe3O4 NPs@rGO NSs for 1.0 mm thin film of 3D f-Fe3O4-VCNTs@rGO hybrids in microwave X-band (8.2-12.4 GHz). This applied microwave synthesis approach for 3D f-Fe3O4-VCNTs@rGO hybrids is simple, fast, reproducible and scalable for advanced EMI shielding materials. It can be concluded that the faceted Fe3O4 NPs on the tip of VCNTs which are grown in-situ on rGO NSs shows synergetic performance for EMI shielding elements in advanced application areas like spacecraft and aircraft1686676CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPnão temnão temThe author (R. Kumar) acknowledges Japan Society for the Promotion of Science (Standard) for international/foreign postdoctoral fellowship (P18063) and JSPS KAKENHI Grant No. 18F18063 (financial support). AVA and SAM would like to acknowledge CNPq and FAPESP (Brazil) for financial suppor

Burning Graphene Layer-by-Layer

Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in &quot;cold-wall&quot; reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material

Physiochemically Distinct Surface Properties of SU‑8 Polymer Modulate Bacterial Cell-Surface Holdfast and Colonization

SU-8 polymer is an excellent platform for diverse applications due to its high aspect ratio of micro/nanostructure fabrication and exceptional physicochemical and biocompatible properties. Although SU-8 polymer has often been investigated for various biological applications, how its surface properties influence the interaction of bacterial cells with the substrate and its colonization is poorly understood. In this work, we tailor SU-8 nanoscale surface properties to investigate single-cell motility, adhesion, and successive colonization of phytopathogenic bacteria, Xylella fastidiosa. Different surface properties of SU-8 thin films have been prepared using photolithography processing and oxygen plasma treatment. A more significant density of carboxyl groups in hydrophilic plasma-treated SU-8 surfaces promotes faster cell motility in the earlier growth stage. The hydrophobic nature of pristine SU-8 surfaces shows no trackable bacterial motility and 5–10 times more single cells adhered to the surface than its plasma-treated counterpart. In addition, plasma-treated SU-8 samples suppressed bacterial adhesion, with surfaces showing less than 5% coverage. These results not only showcase that SU-8 surface properties can impact the spatiotemporal bacterial behavior but also provide insights into pathogens’ prominent ability to evolve and adapt to different surface properties