In this paper, we experimentally study the unique surface sensing property and enhanced sensitivity in subwavelength grating (SWG) based microring resonator biosensors versus conventional ring resonator biosensors. In contrast to a conventional ring, the effective sensing region in the SWG microring resonator includes not only the top and side of the waveguide, but also the space between the silicon pillars on the propagation path of the optical mode. It leads to an unique property of thickness-independent surface sensitivity versus common evanescent wave sensors; in other words, the surface sensitivity remains constantly high with progressive attachment of biomolecules to the sensor surface. To increase the robustness of performance of ring shaped circular SWG biosensors, we experimentally demonstrate silicon SWG racetrack resonators. A quality factor of 9800 and bulk sensitivity (S) is ∼429.7 nm/RIU (refractive index per unit) results in an intrinsic detection limit (iDL) 3.71×10-4 RIU in racetrack SWG biosensors while still retaining the accumulated surface thickness properties of circular rings.

Due to their highly favorable materials properties such as direct bandgap, appropriate bandgap energy against solar spectrum, and ability to form multiple junctions, epitaxially grown III-V compound semiconductors such as gallium arsenide have provided unmatched performance over silicon in solar energy harvesting. However, their large-scale deployment in terrestrial photovoltaics remains as a daunting challenge mainly due to the high cost of growing device-quality epitaxial materials. In this regard, releasable multilayer epitaxial growth in conjunction with printing-based deterministic materials assemblies represents a promising approach that can overcome this challenge but also create novel engineering designs and device functionalities, each with significant practical values in photovoltaic technologies. This article will provide an overview of recent advances in materials design, fabrication concept, and nanophotonic light management of multilayer-grown nanomembrane-based GaAs solar cells aiming for high performance, cost-efficient platforms of III-V photovoltaics.

Thin anodic porous alumina (tAPA), engineered by electrochemical anodization of aluminum and post-fabrication etching, has already shown surface-enhanced Raman scattering (SERS) activity, after overcoating with a thin gold film. On the other hand, the tAPA nanoporous surface, which is biocompatible and presents controlled roughness, has been extensively investigated as a substrate for living cell cultures. Here, we are interested in exploiting the nanoporosity of tAPA as a drug reservoir and demonstrating drug-delivery capabilities of these substrates which can be combined with the above cell-seeding and SERS activities. We focused on the loading/elution of a test drug, the nonsteroidal anti-inflammatory and analgesic molecule Diclofenac. We carried out pore loading of differently concentrated aqueous solutions of the test drug, and characterized the elution profiles by UV-Vis absorbance, using the lipid bilayers coated on the top surface as a mechanism for retarded elution from the pores, providing a more sustained release. We also demonstrated that, by changing an environmental parameter such as the pH, we can trigger an increased release of the drug. Additionally, we investigated the tAPA adsorption properties by quartz crystal microbalance technique with dissipation monitoring (QCM-D). For the purpose, anodization was carried out on an Al-coated quartz, which resulted in successful fabrication of tAPA on the sensor. Finally, the process of lipid bilayer formation on the nanoporous sensor, as well as the test drug loading, was demonstrated by QCM-D.

As the global populations grow, water demand and pollution of water resources will increase. As a consequence, water borne disease outbreaks are on the rise and current disinfection methods have been shown to be ineffective in inactivating all pathogens during water treatment. Aluminum oxide nanoparticles (Al2O3 NPs) have been shown to poses antimicrobial properties. Also, Al2O3 has high thermal and chemical stability, which makes these NPs an excellent candidate for water treatment applications. Thus, the objective of this work is to assess the bactericidal properties of Al2O3 NPs synthesized using a polyol-based process in presence of polyvinylpyrrolidone (PVP). For practical applications nanoparticles must be immobilized in a medium to ensure that particles are not dispersed into the treated water. For this reason, synthesized nanoparticles were dispersed in electrospun polyacrylonitrile (PAN) membranes to also evaluate the bacterial removal capacity. X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis suggests that synthesized nanoparticles are γ-Al2O3 after annealing at 800°C for 6 hours. Scanning Electron Microscopy (SEM) characterization was used to determine the morphology and size of synthesized nanoparticles. Composite electrospun membranes were also characterized by XRD, FT-IR, and SEM. The bactericide activity of the synthesized γ-Al2O3 NPs and commercially available Al2O3 particles was evaluated by the disc diffusion method against E. coli bacteria. Also, Al2O3-PAN composite electrospun membranes bacterial filtration capacity was tested. Both synthesized and industrially produced particles exhibited antibacterial activity against E. coli, but polyol-based synthesized nanoparticles demonstrated better bactericide properties. The bacterial removal capacity of PAN and PAN/Al2O3 fibers was comparable to that of paper filters.

Since the discovery of graphene in 2004, graphene has already been one of the researching hotspots in the material science. As a promising method, electrochemical exfoliation has drawn great attention for producing graphene on industrial scale with high efficiency, low cost, and non-pollution. However, like other wet-chemical methods, the induced oxidation and chemical functionalization are unavoidable during the exfoliation process. Several solutions have been reported to overcome this issue and improve the graphene quality. In this review, we summarize the recent progress in preparation and potential applications of high-quality graphene via electrochemical exfoliation in acidic electrolytes, focusing on the technological innovation and related properties of obtained high-quality graphene.