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We report a method to fabricate micro-pore arrays on a copper sheet by a 355 nm UV nanosecond pulse laser, and investigate the effects of surface microstructures and micro-pore spacing on the wettability of the formed copper micro-mesh. We found that the surface was initially hydrophilic, but changed to superhydrophobic-oleophilic with water contact angle 151° and oil contact angle about 10° after exposed to ambient environment for 14 days. We analysed the surface morphologies of the processed samples with a three-dimensional profilometer, measured the water and oil contact angles, and characterized the surface by a field emission environmental scanning electron microscope (FESEM) and energy dispersive X-ray spectrometer (EDS). The surface chemistry changes were confirmed by X-ray photographic spectroscopy (XPS). Effective oil-water separation performance of the fabricated copper mesh was demonstrated. Learning from the natural change, we designed a coating material containing C8 long C-C (H) chain and coated onto the freshly prepared copper mesh to convert the surface property into a preferred superhydrophobic-oleophilic nature. This study provides a controllable methodology consisting laser processing and surface modification for making micro-pore copper mesh as a simple and effective method for oil-water separation.

Controlled self-assembly of plasmonic photonic nanostructures provides a cost-effective and efficient methodology to expand plasmonic photonic nano-platforms with unique, tunable, and coupled optical characteristics. Keeping advantages and challenges in view, this review highlights contemporary advancements towards the development of self-assembly of a plasmonic photonic nanostructure using a colloidal solution and a self-assembly modeling technique along with exploring novel optical properties and associated prospects. The potential applications of self-assembled plasmonic photonic nano-systems to investigate next-generation optoelectronic devices, the need to reduce and increase scaling up aspects, and improve the performance, are also covered briefly in the review. The need of considerable efforts for the design and development towards establishing novel cost-effective methods to fabricate controlled self-assembled smart nano-plasmonic platforms is also highlighted in this mini-review. Key confronting issues that precisely limit the self-assemblies of photonic nanostructures and desired integration with other device components, mainly including uniformity within miniaturized devices are also discussed. This review will serve as a guideline and platform to plan advanced research in developing self-assembled plasmonic photonic nano-systems to investigate smart functional optical devices.

Bacterial biofilms formed on touchable surfaces such as displays of electronic devices not only reduce the product service life, but also cause human health issues. There is an urgent need to research the biofilm formation mechanism and methodologies to prevent formation of biofilms on human touchable surfaces. It has been reported that laser-induced graphene (LIG) helps resist biofilm growth, which has been attributed to the atomic composition and sharp edges of graphene. However, LIG alone was not able to retard bacterial growth completely. It has been reported that LIG incorporated with silver (Ag) nanoparticles exhibited enhanced surface antibacterial activity. As a heavy metal, overdose of Ag is harmful to human health. Therefore, a new biocompatible antibacterial agent to replace or reduce the use of Ag is highly important. In this study, we investigate and compare the effect of LIG doped with two types of nanocrystals, i.e., ZnO and silver (Ag)-doped ZnO, on antibacterial actions. A 355 nm ultraviolet (UV) laser was used to produce LIG on a watercolor paper substrate. Formation of few-layer graphene has been verified by Raman spectra. Escherichia coli (E. coli), a representative of Gram-negative bacteria and Staphylococcus aureus (S. aureus), a representative of Gram-positive bacteria were employed for the investigation of the bacteriostatic properties of the LIG paper substrate. Results show that with the incorporation of either the ZnO nanocrystals or the silver (Ag)-doped ZnO nanocrystals into LIG, the antibacterial effect became stronger. It is further shown that the Ag-doped ZnO nanocrystals have superior antibacterial performance to that of the ZnO nanocrystals. The Ag-doped ZnO nanocrystals are potentially an effective and biocompatible antibacterial agent and yet have a much reduced and acceptable level of Ag concentration.

The self-assembled plasmonic nano-enabled photonic crystals (PCs)have been studied as promising platforms to develop next-generation photonic and opto-electronic devices. In this review, we attempt to describe the fundamentals of self-assembled colloidal plasmonic nanostructures and various applications of such devices. Different important aspects, such as interaction between metal NPs (MNPs) and non-metal 3-D crystals, effect of NPs on the spectral properties of materials, the mechanism of plasmonic based PCs, and related challenges and their possible solutions have been demonstrated crucially. The advancements in the self-assembly based plasmonic PCs and their applications are discussed carefully. We believe that nano-enabled self-assembled plasmonic crystals are better candidates of nanostructures to advance photonic technologies with reduced form factor and high performance.

In this research article, we reportthe plasmonic effect exhibited by a self-assembled photonic crystal cavity in nanostructures using asecond harmonic laser exposure. The photonic nanostructures composed of goldnanoparticles (AuNPs),enhancedthe fluorescence properties which undergo into lattice planesand thereby affect thenonlinearproperties.The newlyfabricated colloidal structures exhibited a strong plasmonicinteraction with different laser powersdensity.The outcome of this research presentsthe self-assembled nano-photonic cavity as a suitable plasmonic nanostructure for optoelectronic applications. These nanostructurescan be fabricated using high power lasers source,e.g. dye laser and solid-state laser.

Self-powered devices and micro-sensors are in high demand for intelligent electronics and flexible wearables for applications in medical healthcare and human–computer interactive robotics. Flexible, stretchable, wearable and breathable high-sensitivity sensors that monitor signals from subtle changes in the environment provide solutions for personalized medical healthcare. In this article, we review the fundamental mechanisms, theoretical research, sensor fabrication methodologies, and applications of flexible piezoelectric materials. We focus on the flexibility and stretchability of inorganic, polymer, and bio-piezoelectric materials, explain their properties for physiological signal monitoring, motion detection, and force sensing. We provide an overview of the latest progress in piezoelectronics and piezoelectric photonics, the structures of devices, and self-powering technologies. We compared 10 types of polymers and composites with human skin in terms of elastic modulus and found that PLLA/PDMS, electro-spun PVDF, and ZnO/PVDF possess higher elastic modulus (50, 500, and 27900 MPa respectively) than human skin (18.8 MPa), thus being more suitable for wearable devices. In terms of electrical outputs of piezoelectric materials, polarized cast film has stronger piezoelectric property with output of 14–45.6 V than electro-spun filaments material (output 0.4–9 V). Future research and development should focus on increasing electrical performance while maintaining the required flexibility and durability.

The buildings in tropical climate like Singapore get excessive heat gain throughout the year. Passive cooling can be achieved with IR-shielding coating by blocking the IR radiation from solar light. In this work, antimony-doped tin oxide (ATO) nanocrystals with diameter of 10 nm were synthesized by solvothermal method. The Sb dopant concentration in ATO nanoparticles was optimized towards enhanced IR shielding properties. Sol–gel precursor was formulated with silanes and ATO nanocrystals. Transparent IR shielding coatings were coated on glass for smart window. The optical and IR shielding performance of the coatings were evaluated. By incorporating smaller ATO nanocrystals synthesized by solvothermal synthesis, the IR shielding performance of the coating was greatly improved as compared to that using larger commercial ATO nanoparticles. The IR shielding coating with synthesized ATO nanocrystals can block more than 90% IR while it can maintain more than 80% transmittance at the visible range. The solar heat gain coefficient (SHGC or G-value) of the coating with 10 wt.% synthesized ATO nanocrystals is 0.68 for single layer structure, and decreases to 0.53 with double glazing structure while maintaining good visible transmittance of 60%. Keywords: Solvothermal, ATO, IR shielding coating, Smart window

A thorough experimental investigation of polymer-glass transition temperature (Tg ) is performed on poly(vinyl alcohol) (PVA) and fumed silica nanoparticle (SiNP) composite. This is done together with atomistic molecular dynamics simulations of PVA systems in contact with bare and fully hydroxylated silica. Experimentally, PVA-SiNP composites are prepared by simple solution casting from aqueous solutions followed by its characterization using Fourier-transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and dynamic scanning calorimetry (DSC). Both theoretical and experimentally deduced Tg are correlated with the presence of hydrogen bonding interactions involving OH functionality present on the surface of SiNP and along PVA polymer backbone. Further deconvolution of FTIR data show that inter-molecular hydrogen bonding present between PVA and SiNP surface is directly responsible for the increase in Tg . SiNP filler and PVA matrix ratio is also optimized for a desired Tg increase. An optimal loading of SiNP exists, in order to yield the maximum Tg increase arising from the competition between hydrogen bonding and crowding effect of SiNP.

In this paper, sol–gel-based transparent easy-to-clean (ETC) coatings are fabricated using organic–inorganic hybrid precursors and fluorinated silane-based hydrophobic surfactants. ETC coatings were applied on different plastic materials such as polycarbonate, poly(methyl methacrylate) and polyethylene terephthalate. Due to the low temperature resistance of the plastic materials, usually lower than 120 °C, low temperature processes such as ammonia gas curing and ultraviolet irradiation curing were employed for coatings development. Alumina nanoparticles were used to improve the mechanical properties of the coatings, and antimicrobial effect was realized by incorporation of silver nanoparticles, and high bacterial killing rates were obtained with very low silver concentration (50 ppm). All the coatings developed on different substrates show high water/hexadecane contact angles with good wet scrubbing resistance. Abrasion-resistant multifunctional sol–gel coating on PMMA substrate

We measured the Raman spectra of canthaxanthin which contains 9 CC conjugated double bonds in nonpolar solvent carbon disulfide under different pressures. The results showed that the Raman scattering cross section (RSCS) for C C and C C stretching vibration bands of canthaxanthin first increase and then decrease with the increase of pressure. We assume that the main mechanism of the RSCS values increasing can be attributed to the effect of steric hindrance. And the liquid–solid phase transition of carbon disulfide is occurred under the 0.5312 GPa, which lead to the decrease of RSCS values.

In this paper, the author shows that a self-assembled monolayer of decanethiol (C 10 -SAM) molecules, which is only ∼1.3 nm in optical thickness, can be easily detected using 2D plasmonic crystal (PCL) with an angular shift as large as 2.86° which is more than one order of magnitude higher than conventional prism-based SPR and an estimated sensitivity larger than 900°/RIU is possible. The experimental data are accompanied by a model description that explains the principle of sensitivity enhancement. However the field enhancement of 2D PCL will be further improved when the optimum SPP excitation conditions are met.

In this paper an engineered dielectric material is used to introduce porosities which will change the plasmonic crystal's (PCL) refractive index profile, its excitation conditions, electromagnetic (EM) characteristics and propagations. SPP excitation is moved from positive diffraction order (m=1) to negative diffraction order range (m=−1); hence the increment in wavelength will decrease the resonant angle. The m=−1 opens the possibility to control and manipulate the preferred excitation conditions of SPP for different purposes such as optical devices and sensors.

241 p. Semiconductor quantum dots (QDs) offer significant advantages over organic fluorophores; however, the cytotoxicity, complex and toxic synthesis processes, and missing colours in blue-violet range (< 490nm) are major issues for their extended in vivo bio-applications. While ZnO is a good candidate because of its wide band-gap, large exciton binding energy, bio-compatible core material, and bio-friendly synthesis processing, chemically pure ZnO colloidal nanocrystals in quantum size, with excellent optical properties, and bio-compatible surface functionalities are not yet available. DOCTOR OF PHILOSOPHY (MSE)