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The aims of this paper are to investigate the influence of direct current (DC) electric field on separation and orientation of carbon nanotubes (CNTs) in spray-coated layers and apply this method to the fabrication of elastic and transparent electrodes. The orientation of CNTs in the form of paths in the direction of electrical conduction should increase the electrode conductivity without decreasing its optical transmission.

Materials are deposited using vacuum-free, ultra-fine nozzle spray coating technique, easily applicable for large-scale production. After the deposition of carbon nanomaterials, nanoparticles are oriented in the electric field and initially cured with infrared halogen lamp to evaporate solvents and preserve orientation of the nanoparticles in the deposited layer. Afterwards, layers are cured in a chamber dryer to obtain desired properties. Nanoparticles orientation and carbon nanomaterials separation via DC electric field are analysed, and the optical and electrical properties of prepared electrodes are measured.

Experiments described in this paper showed that DC electric field can be applied provide separation and orientation of CNTs and combined with spray coating technique, can be used as additional tool for tuning the conductivity of flexible and transparent electrodes by decreasing the sheet resistance about five times.

The results showed that spray coating combined with electric field orientation is a promising solution of obtaining elastic and transparent electrodes with oriented carbon particles. According to the authors’ knowledge, none of the experiments was directed to obtain DC electric field-oriented transparent layers produced with the use of spray coating technique.

The aim of this paper was to verify applicability of graphene-based sensors for voltammetric and amperometric measurements of low-concentration compounds in biological fluids.

Using the screen printing method, electrochemical sensors were manufactured on polymethylmetacrylate foil using a paste consisting of organic solvents and graphene nanopetals. As the model of a biological fluid tear film was chosen, the compound chosen as the analyte was H₂O₂, which is produced in oxidation of biological compounds. Tear film analog was prepared, in which, the measurements were carried out in a wide range of concentrations to determine the oxidation potential of H₂O₂ through square-wave voltammetry. The second series of amperometric measurements was carried out for concentrations between 0 and 30 μM/L, which is the lower range of physiological glucose concentration in tear films.

The sensors presented linearity for concentrations from 0 to 3.5 per cent. Mean linear correlation coefficient between the peak current and the concentration for the examined sensors was 0.9764. Mean sensitivity was 434.4 mA·M−1·L−1.

Results indicate a need for optimization of the sensors ' performance. Main parameters to be improved are surface area of electrodes and purity of the graphene layer, as well as uniformity of the manufacturing process to improve accuracy and repeatability of measurements.

Technology and materials used present an opportunity for creating low-cost, miniaturized and biocompatible sensors to be used in medical monitoring.

Printed electronics technology described was not investigated previously in the field of biological sensors and could contribute to the solving of vital medicine problems.

A comparison of electric and viscosity percolation threshold is crucial from the scientific and technical points of view to understand the features and capabilities of heterogeneous graphene composite materials and properly select the functional phase volume. Therefore, the purpose of this paper is to present the analysis of the electrical and rheological percolation thresholds in the polymer–graphene screen printing pastes and the analysis of the relation between these two parameters.

In the paper, the properties of polymer-based pastes with graphene nanoplatelets were tested: paste viscosity and printed layers conductivity. The tests of pastes with different filler content allowed to determine both the electrical and rheological percolation thresholds using power law, according to Kirkpatrick’s percolation model.

The electrical percolation threshold for graphene nanoplatelets (GNPs) in the composite was 0.74 Vol.% when the rheological percolation threshold is observed to be at 1.00 Vol.% of nanoplatelets. The percolation threshold values calculated using the Kirkpatrick’s percolation model were 0.87 and 0.5 Vol.% of GNPs in the paste for electrical and rheological percolation thresholds, respectively.

Recently, GNPs are becoming more popular as the material of the functional phase in screen printing heterophase materials, because of their unique mechanical and electrical properties. However, till date no research presented in the literature is related to the direct comparison of both the electrical and rheological percolation thresholds. Such analysis is important for the optimization of the printing process toward the highest quality of printed conductive paths, and finally the best electrical properties.

New types of substrates were used for fabrication of printed electroluminescent structures. Polymer foils mainly used as substrates for such optoelectronic elements were replaced with paper and textiles. Printing on non-transparent substrate requires elaboration of printed transparent electrode, while usually polyester foils with sputtered ITO transparent electrodes are used. The paper aims to discuss these issues.

Electroluminescent structures were fabricated with elaborated polymer compositions filled with nanomaterials, such as carbon nanotubes and graphene platelets, dielectric and luminophore nanopowders. Structures were printed as “reverse stack”, where transparent electrode is printed on top of the last luminophore layer. For that carbon nanotubes and graphene platelets filled composition was used, deposited with spray-coating technique.

Main issue with new substrates is proper wetting with the use of screen-printing pastes, and much higher roughness especially for textiles.

Fully functional structures were obtained, but several disadvantages were observed that needs to be eliminated in further studies.