Carbon loaded polystyrene microneedle patches have been prepared using silicone micromoulding techniques and the ability of the needles to serve as viable transdermal sensors has been evaluated. The population of quinone groups at the interface of the embedded carbon nanoparticles was increased through anodisation and their pH dependent redox transitions exploited as the basis of a reagentless pH sensor. The peak position of the quinone oxidation process was found to shift in accordance with Nernstian behaviour and the influence of penetration depth on response has been investigated. The analytical applicability of the microneedle electrode patch was critically evaluated through using tomato skin as model transdermal skin mimic. Despite the increased complexity of the matrix, the microneedle sensor response was found to compare favourably with conventional/commercial pH probes.

Electrochemical anodisation techniques are regularly used to modify carbon fiber surfaces as a means of improving electrochemical performance. A detailed study of the effects of oxidation (+ 2 V) in alkaline media has been conducted and Raman, XPS and SEM analyses of the modification process have been tallied with the resulting electrochemical properties. The co-application of ultrasound during the oxidative process has also been investigated to determine if the cavitational and mass transport features influence both the physical and chemical nature of the resulting fibers. Marked discrepancies between anodisation with and without ultrasound is evident in the C1s spectra with variations in the relative proportions of the electrogenerated carbon-oxygen functionalities. Mechanisms that could account for the variation in surface species are considered. Graphic abstract

Surfactant free synthesis of copper nanoparticles by using atmospheric plasma pressure.

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Alkali‐activated functionalized carbon nanotubes (AFCNTs) and 2D nanostructured MoS2 are investigated as a novel hybrid material for energy‐storage applications. The nanoflower‐like 2D MoS2 is grown on the surface of AFCNT using the controlled one‐step hydrothermal technique. The activation of functionalized carbon nanotubes results in greater performance due to the improved surface area. The Brunauer–Emmett–Teller (BET) surface area of the AFCNTs is found to be 594.7 m2 g−1 which is almost 30 times of the as‐prepared carbon nanotubes (CNTs). The improved surface area with attached hydroxyl and carboxylic functional groups helps in the attachment of MoS2 nanoflowers onto the AFCNT, thus reducing the interfacial resistance and providing an easy path for electron transfer. The electrochemical analysis shows a high specific capacitance of 516 F g−1 at 0.5 A g−1 with a corresponding energy density of 71.76 Wh kg−1, which is an encouraging reported value from AFCNT and MoS2 hybrid material. To the best of our knowledge, herein, the first report on AFCNTs and 2D MoS2 nanostructured hybrid electrode material for supercapacitor applications is provided, and promising results in terms of specific capacitance, energy density, and power density by boosting the properties of individual material are explained.

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Conductive microneedle patches consisting of carbon nanoparticles embedded in a polystyrene matrix have been prepared using micro-moulding techniques. The interfacial properties of the structures before and after electrochemical etching have been characterised using X-ray photoelectron spectroscopy and contact angle. Anodisation of the needles leads to a significant increase in oxygen functionality and is shown to dramatically improve the electroanalytical capabilities of the microneedle array. The detection of uric acid in horse blood was used as a model system through which to assess the performance of the system. The composite approach is shown to lead to viable carbon-based sensors and can offer a rapid prototype option for the development of tailored microneedle systems.

Plasma-liquid interactions are becoming increasingly interesting due to their key features such as non-faradaic, non-equilibrium behaviour as well electron-driven reactions, therefore with potential strong impact for several promising applications. However,...