Surface-enhanced Raman spectroscopy: a half-century historical perspective.

Surface-enhanced Raman spectroscopy (SERS) has evolved significantly over fifty years into a powerful analytical technique. This review aims to achieve five main goals. (1) Providing a comprehensive history of SERS's discovery, its experimental and theoretical foundations, its connections to advances in nanoscience and plasmonics, and highlighting collective contributions of key pioneers.

Toward a Procedure for the Template Free Growth of Te Nanowires Across an Insulator by Electrodeposition.

In this work, we present a method for direct, site-selective growth of tellurium nanowires by electrochemical deposition. The Te nanowires were grown laterally between two specially designed nanoband electrodes across a gap, and over a dielectric material, forming a lateral device structure directly. The resulting wires are crystalline and phase pure, as evidenced by Raman spectroscopy, EDS (energy dispersive X-ray spectroscopy), and ADF-STEM (annular dark field scanning transmission electron microscopy).

Tunable Neuromorphic Switching Dynamics via Porosity Control in Mesoporous Silica Diffusive Memristors.

In response to the growing need for efficient processing of temporal information, neuromorphic computing systems are placing increased emphasis on the switching dynamics of memristors. While the switching dynamics can be regulated by the properties of input signals, the ability of controlling it via electrolyte properties of a memristor is essential to further enrich the switching states and improve data processing capability. This study presents the synthesis of mesoporous silica (mSiO) films using a sol-gel process, which enables the creation of films with controllable porosities.

Film before aggregates: an GISAXS study on electrochemically assisted surfactant assembly.

The process of electrochemically assisted surfactant assembly was followed in real time by grazing incidence small angle X-ray scattering with the aim to deconvolute the formation of mesoporous silica film and unwanted porous particles. The X-ray technique proved to be useful for the characterisation of this process, as it takes place at a very dynamic, solid/liquid interface. This paper shows the electrochemically driven onset and evolution of silica/surfactant structures.

Multiframe-based non-local means denoising for Raman spectra.

A method for denoising Raman spectra is presented in this paper. The approach is based on the principle that the original signal can be restored by averaging pixels based on structure similarity. Similarity searching and averaging are not limited to the neighbouring pixels but extended throughout the entire signal range across different frames.

Grating-incoupled waveguide-enhanced Raman sensor.

We report a waveguide-enhanced Raman spectroscopy (WERS) platform with alignment-tolerant under-chip grating input coupling. The demonstration is based on a 100-nm thick planar (slab) tantalum pentoxide (Ta2O5) waveguide and the use of benzyl alcohol (BnOH) and its deuterated form (d7- BnOH) as reference analytes. The use of grating couplers simplifies the WERS system by providing improved translational alignment tolerance, important for disposable chips, as well as contributing to improved Raman conversion efficiency.

Flexible Memristor Devices Using Hybrid Polymer/Electrodeposited GeSbTe Nanoscale Thin Films.

We report on the development of hybrid organic-inorganic material-based flexible memristor devices made by a fast and simple electrochemical fabrication method. The devices consist of a bilayer of poly(methyl methacrylate) (PMMA) and Te-rich GeSbTe chalcogenide nanoscale thin films sandwiched between Ag top and TiN bottom electrodes on both Si and flexible polyimide substrates. These hybrid memristors require no electroforming process and exhibit reliable and reproducible bipolar resistive switching at low switching voltages under both flat and bending conditions.

Mesoporous silica films as hard templates for electrodeposition of nanostructured gold.

Metallic nanostructures have widespread applications in fields including materials science, electronics and catalysis. Mesoporous silica films synthesised by evaporation induced self-assembly and electrochemically assisted self-assembly with pores below 10 nm were used as hard templates for the electrodeposition of Au nanostructures. Electrodeposition conditions were optimised based on pore orientation and size.

3D-structured mesoporous silica memristors for neuromorphic switching and reservoir computing.

Memristors are emerging as promising candidates for practical application in reservoir computing systems that are capable of temporal information processing. Here, we experimentally implement a physical reservoir computing system using resistive memristors based on three-dimensional (3D)-structured mesoporous silica (mSiO) thin films fabricated by a low cost, fast and vacuum-free sol-gel technique. The learning capability and a classification accuracy of 100% on a standard machine learning dataset are experimentally demonstrated.

AC-assisted deposition of aggregate free silica films with vertical pore structure.

Silica thin films with vertical nanopores are useful to control access to electrode surfaces and may act as templates for growth of nanomaterials. The most effective method to produce these films, electrochemically assisted surfactant assembly, also produces aggregates of silica particles. This paper shows that growth with an AC signal superimposed onto the potential avoids the aggregates and only very small numbers of single particles are found.

Selection and characterisation of weakly coordinating solvents for semiconductor electrodeposition.

Weakly coordinating solvents, such as dichloromethane, have been shown to be attractive for the electrodeposition of functional p-block compound and alloy semiconductors for electronic device applications. In this work the use of solvent descriptors to define weakly coordinating solvents and to identify new candidates for electrochemical applications is discussed. A set of solvent selection criteria are identified based on Kamlet and Taft's π*, and parameters: suitable solvents should be polar (π* ≥ 0.

LiFePO Battery Material for the Production of Lithium from Brines: Effect of Brine Composition and Benefits of Dilution.

Lithium battery materials can be advantageously used for the selective sequestration of lithium ions from natural resources, which contain other cations in high excess. However, for practical applications, this new approach for lithium production requires the battery host materials to be stable over many cycles while retaining the high lithium selectivity. Here, a nearly symmetrical cell design was employed to show that LiFePO shows good capacity retention with cycling in artificial lithium brines representative of brines from Chile, Bolivia and Argentina.

Tungsten disulfide thin films electrodeposition from a single source precursor.

We report a simple process for the electrodeposition of tungsten disulfide thin films from a CHCl-based electrolyte using a tailored single source precursor, [NEt][WSCl]. This new precursor incorporates the 1 : 2 W:S ratio required for formation of WS, and eliminates the need for an additional proton source in the electrolyte to remove excess sulfide. The electrochemical behaviour of [NEt][WSCl] is studied by cyclic voltammetry and electrochemical quartz crystal microbalance techniques, and the WS thin films are grown by potentiostatic electrodeposition.

Waveguide Enhanced Raman Spectroscopy for Biosensing: A Review.

Waveguide enhanced Raman spectroscopy (WERS) utilizes simple, robust, high-index contrast dielectric waveguides to generate a strong evanescent field, through which laser light interacts with analytes residing on the surface of the waveguide. It offers a powerful tool for the direct identification and reproducible quantification of biochemical species and an alternative to surface enhanced Raman spectroscopy (SERS) without reliance on fragile noble metal nanostructures. The advent of low-cost laser diodes, compact spectrometers, and recent progress in material engineering, nanofabrication techniques, and software modeling tools have made realizing portable and cheap WERS Raman systems with high sensitivity a realistic possibility.

Complete Electrolytic Plastron Recovery in a Low Drag Superhydrophobic Surface.

We present a superhydrophobic surface capable of recovering the lubricious gas layer known as the "plastron" from a fully wetted state underwater. It is shown that full plastron recovery is possible without a second layer of structural hierarchy, which is prone to irreversible wetting transitions. This allows us to use a cheap, fast, and potentially scalable method to fabricate the surface from silicone and carbon black in a molding process.

Large-Area Electrodeposition of Few-Layer MoS on Graphene for 2D Material Heterostructures.

Heterostructures involving two-dimensional (2D) transition metal dichalcogenides and other materials such as graphene have a strong potential to be the fundamental building block of many electronic and optoelectronic applications. The integration and scalable fabrication of such heterostructures are of the essence in unleashing the potential of these materials in new technologies. For the first time, we demonstrate the growth of few-layer MoS films on graphene via nonaqueous electrodeposition.

Thermoelectric Properties of Bismuth Telluride Thin Films Electrodeposited from a Nonaqueous Solution.

We report the thermoelectric properties of BiTe thin films electrodeposited from the weakly coordinating solvent dichloromethane (CHCl). It was found that the oxidation of porous films is significant, causing the degradation of its thermoelectric properties. We show that the morphology of the film can be improved drastically by applying a short initial nucleation pulse, which generates a large number of nuclei, and then growing the nuclei by pulsed electrodeposition at a much lower overpotential.

Direct Detection and Discrimination of Nucleotide Polymorphisms Using Anthraquinone Labeled DNA Probes.

A novel electrochemical detection approach using DNA probes labeled with Anthraquinone (AQ) as a reporter moiety has been successfully exploited as a method for the direct detection of DNA targets. This assay uses simple voltammetry techniques (Differential Pulse Voltammetry) to exploit the unique responsiveness of AQ to its chemical environments within oxygenated aqueous buffers, providing a specific detection mechanism as a result of DNA hybridization. This measurement is based on a cathodic shift of the reduction potential of the AQ tag and the concurrent reduction in peak current upon DNA binding.

Using GISAXS to Detect Correlations between the Locations of Gold Particles Electrodeposited from an Aqueous Solution.

Electrodeposition is a powerful tool for the bottom-up fabrication of novel electronic devices. This necessitates a complete understanding of the deposition process beyond the classical description using current transients. Recent calculations predict deviations within the spatial arrangement of electrodeposited particles, away from random nucleation.

Studying direct electron transfer by site-directed immobilization of cellobiose dehydrogenase.

Covalent coupling between a surface exposed cysteine residue and maleimide groups was used to immobilize variants of cellobiose dehydrogenase (CDH) at multiwall carbon nanotube electrodes. By introducing individual cysteine residues at particular places on the surface of the flavodehydrogenase domain of the flavocytochrome we are able to immobilize the different variants in different orientations. Our results show that direct electron transfer (DET) occurs exclusively through the haem cofactor and that the redox potential of the haem is unaffected by the orientation of the enzyme.

Waveguide Absorption Spectroscopy of Bovine Serum Albumin in the Mid-Infrared Fingerprint Region.

Protein sensing in biological fluids provides important information to diagnose many clinically relevant diseases. Mid-infrared (MIR) absorption spectroscopy of bovine serum albumin (BSA) is experimentally demonstrated on a germanium on silicon (GOS) waveguide in the 1900-1000 cm (5.3-10.