Search

Surface-enhanced Raman spectroscopy (SERS) technology is an attractive method for the prompt and accurate on-site screening of illicit drugs. As portable Raman systems are available for onsite screening, the readiness of SERS technology for sensing applications is predominantly dependent on the accuracy, stability and cost-effectiveness of the SERS strip. An atmospheric-pressure plasmaassisted chemical deposition process that can deposit an even distribution of nanogold particles in a one-step process has been developed. The process was used to print a nanogold film on a paperbased substrate using a HAuCl4 solution precursor. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the gold has been fully reduced and that subsequent plasma post-treatment decreases the carbon content of the film. Results for cocaine detection using this substrate were compared with two commercial SERS substrates, one based on nanogold on paper and the currently available best commercial SERS substrate based on an Ag pillar structure. A larger number of bands associated with cocaine was detected using the plasma-printed substrate than the commercial substrates across a range of cocaine concentrations from 1 to 5000 ng/mL. A detection limit as low as 1 ng/mL cocaine with high spatial uniformity was demonstrated with the plasma-printed substrate. It is shown that the plasma-printed substrate can be produced at a much lower cost than the price of the commercial substrate.

A novel approach to significantly enhance and comprehensively assess the level of nanochannel ordering in self-assembled nanoporous membranes is proposed and tested. An advanced technique based on a two-step anodization and two-step chemical treatment was used to prepare the perfect through membranes by opening channels from the bottom via electrochemical enlargement, and chemical removal of a residual metal and barrier alumina layer. The influence of the process parameters on the self-assembled ordering was studied, and various methods of order assessment were proposed and tested, such as distributions of equivalent disc radii, 2D Fourier transformations, autocorrelation, Hough transformations, Minkowski connectivity, and distributions of nanochannel centre positions. We have demonstrated that self-assembled ordering in nanoscaled membranes could be efficiently tuned by the process parameters, and different assessment methods should be used to comprehensively characterize the order of nanochannels in the nanoporous membranes. To demonstrate the potential of this technique, we show simulations of the narrowing of plasmon spectra in these materials. The proposed fabrication and assessment methods could be used to drastically enhance the properties of nanoporous membranes for nanoelectronics, filters, sensors, bio-active devices and other advanced emerging applications. Finally, our approach could be used for enhancing and tailoring other self-assembled systems and devices of considerable complexity.

Further development of the near-Earth satellite infrastructure as well as plans for colonization of the Moon and Mars require innovative materials and technologies to produce efficient space assets capable of active functioning for several years. Therefore, the development of compact and efficient devices has bloomed exponentially. Critical components of such devices, propulsion systems that include thrusters, and feed and power systems, have to be efficient and compact. Moreover, these systems shall be simple and cheap, to satisfy the need for thousands of small satellites planned to be launched in the near future. Herein, the design of a 3D-printed, reinforced multilayered material system for gas supply to be used in CubeSats and small satellites of a 1U (10 × 10 × 11.3 cm) form factor is described. The main objective of the system is to provide 0.1 standard cubic centimeter per minute (sccm) of propellant to the thruster. To achieve that, a material system is designed for a propellant tank of ≈50 × 100 mm.

Increasingly intricate in their composition and structural organization, hierarchical multicomponent metamaterials with nonlinear spatially reconfigurable functionalities challenge the intrinsic constraints of natural materials, revealing tremendous potential for the advancement of biochemistry, nanophotonics, and medicine. Recent breakthroughs in high-resolution nanofabrication utilizing ultranarrow, precisely controlled ion or laser beams have enabled assembly of architectures of unprecedented structural and functional complexity, yet costly, time- and energy-consuming high-resolution sequential techniques do not operate effectively at industry-required scale. Inspired by the fictional Baron Munchausen's fruitless attempt to pull himself up, it is demonstrated that metamaterials can undergo intrinsically driven self-assembly, metaphorically pulling themselves up into existence. These internal drivers hold a key to unlocking the potential of metamaterials and mapping a new direction for the large-area, cost-efficient self-organized fabrication of practical devices. A systematic exploration of these efforts is presently missing, and the driving forces governing the intrinsically driven self-assembly are yet to be fully understood. Here, recent progress in the self-organized formation and self-propelled growth of complex hierarchical multicomponent metamaterials is reviewed, with emphasis on key principles, salient features, and potential limitations of this family of approaches. Special stress is placed on self-assembly driven by plasma, current in liquid, ultrasonic, and similar highly energetic effects, which enable self-directed formation of metamaterials with unique properties and structures.

Thermal chemical vapour deposition techniques for graphene fabrication, while promising, are thus far limited by resource-consuming and energy-intensive principles. In particular, purified gases and extensive vacuum processing are necessary for creating a highly controlled environment, isolated from ambient air, to enable the growth of graphene films. Here we exploit the ambient-air environment to enable the growth of graphene films, without the need for compressed gases. A renewable natural precursor, soybean oil, is transformed into continuous graphene films, composed of single-to-few layers, in a single step. The enabling parameters for controlled synthesis and tailored properties of the graphene film are discussed, and a mechanism for the ambient-air growth is proposed. Furthermore, the functionality of the graphene is demonstrated through direct utilization as an electrode to realize an effective electrochemical genosensor. Our method is applicable to other types of renewable precursors and may open a new avenue for low-cost synthesis of graphene films.

Material processing techniques utilizing low-temperature plasmas as the main process tool feature many unique capabilities for the fabrication of various nanostructured materials. As compared with the neutral-gas based techniques and methods, the plasma-based approaches offer higher levels of energy and flux controllability, often leading to higher quality of the fabricated nanomaterials and sometimes to the synthesis of the hierarchical materials with interesting properties. Among others, nanoscale biomaterials attract significant attention due to their special properties towards the biological materials (proteins, enzymes), living cells and tissues. This review briefly examines various approaches based on the use of low-temperature plasma environments to fabricate nanoscale biomaterials exhibiting high biological activity, biological inertness for drug delivery system, and other features of the biomaterials make them highly attractive. In particular, we briefly discuss the plasma-assisted fabrication of gold and silicon nanoparticles for bio-applications; carbon nanoparticles for bioimaging and cancer therapy; carbon nanotube-based platforms for enzyme production and bacteria growth control, and other applications of low-temperature plasmas in the production of biologically-active materials.