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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.

Because of the bioaccumulation effect, organophosphorus pesticides cause long-term damage to mammals, even at small concentrations. The ability to perturb the phospholipid bilayer structure as well as the overstimulation of cholinergic receptors makes them hazardous to humans. Therefore, there is a need for a quick and inexpensive detection of organophosphorus pesticides for agricultural and household use. As organophosphorus pesticides are acetylcholinesterase (AChE) inhibitors, biosensors using this mechanism hold a great promise to meet these requirements with a fraction of reagents and time used for measurement comparing to laboratory methods. This study aims to manufacture AChE-coated, screen-printed carbon electrodes applicable in such amperometric biosensors.

AChE enzyme, known for catalytic activity for the hydrolysis of acetylthiocholine (ATCh), could be used to obtain electrochemically active thiocholine from acetylthiocholine chloride in aqueous solutions. Using Malathion’s inhibitory effect towards AChE, pesticides’ presence can be detected by reduction of anodic oxidation peaks of thiocholine in cyclic voltammetry.

The conducted research proved that it is possible to detect pesticides using low-cost, simple-to-manufacture screen-printed graphite (GR) electrodes with an enzymatic (AChE) coating. Investigated electrodes displayed significant catalytic activity to the hydrolysis of ATCh. Owing to inhibition effect of the enzyme, amperometric response of the samples decreased in pesticide-spiked solution, allowing determination of organophosphorus pesticides.

Printed electronics has grown significantly in recent years as well as research focused on carbon-based nanocomposites. Yet, the utilization of carbon nanocomposites in screen-printed electronics is still considered a novelty in the market. Biosensors have proved useful not only in laboratory conditions but also in home applications, as glucometers are a superior solution for glucose determination for personal use. Although pesticides could be detected accurately using chromatography, spectroscopy, spectrometry or spectrophotometry, the market lacks low-cost, disposable solutions for pesticide detection applicable for household use. With biosensing techniques and electric paths screen-printed with GR or graphene nanocomposites, this preliminary research focuses on meeting these needs.

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.

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.

The paper aims to present the research results related to transparent heating elements made from carbon nanomaterials. Heating elements were fabricated only with cost-effective techniques with the aim to be easily implemented in large area applications. Presented materials and methods are an interesting alternative to vacuum deposition of transparent resistive layers and etching of low-resistive patterns. Fabricated heating elements were designed to be used as de-icing structures in roof-top windows.

The paper presents the research results related to transparent heating elements made from carbon nanomaterials. Heating elements were fabricated only with cost-effective techniques with the aim to be easily implemented in large area applications. Presented materials and methods are an interesting alternative to vacuum deposition of transparent resistive layers and etching of low-resistive patterns. Fabricated heating elements were designed to be used as de-icing structures in roof-top windows.

The sheet resistance of obtained layers was between 9 and 11 kΩ/□; however, double-walled carbon nanotubes showed significantly higher optical transmission (around 70 per cent) than graphene nanoplatelets (around 55 per cent for visible and near infrared range). The amount of polymer resin had the influence on the paints stability, electrical properties and coatings adhesion.

Results show a novel method of fabrication of a large area and transparent heating elements with tunable resistance done through the change of spray coating paint composition.

The purpose of this study is to develop a molecular imprinting electrochemical sensor for the specific detection of the anticancer drug amsacrine. The sensor used a composite of bacterial cellulose (BC) and silver nanoparticles (AgNPs) as a platform for the immobilization of a molecularly imprinted polymer (MIP) film. The main objective was to enhance the electrochemical properties of the sensor and achieve a high level of selectivity and sensitivity toward amsacrine molecules in complex biological samples.

The composite of BC-AgNPs was synthesized and characterized using FTIR, XRD and SEM techniques. The MIP film was molecularly imprinted to selectively bind amsacrine molecules. Electrochemical characterization, including cyclic voltammetry and electrochemical impedance spectroscopy, was performed to evaluate the modified electrode’s conductivity and electron transfer compared to the bare glassy carbon electrode (GCE). Differential pulse voltammetry was used for quantitative detection of amsacrine in the concentration range of 30–110 µM.

The developed molecular imprinting electrochemical sensor demonstrated significant improvements in conductivity and electron transfer compared to the bare GCE. The sensor exhibited a linear response to amsacrine concentrations between 30 and 110 µM, with a low limit of detection of 1.51 µM. The electrochemical response of the sensor showed remarkable changes before and after amsacrine binding, indicating the successful imprinting of amsacrine in the MIP film. The sensor displayed excellent selectivity for amsacrine in the presence of interfering substances, and it exhibited good stability and reproducibility.

This study presents a novel molecular imprinting electrochemical sensor design using a composite of BC and AgNPs as a platform for MIP film immobilization. The incorporation of BC-AgNPs improved the sensor’s electrochemical properties, leading to enhanced sensitivity and selectivity for amsacrine detection. The successful imprinting of amsacrine in the MIP film contributes to the sensor's specificity. The sensor's ability to detect amsacrine in a concentration range relevant to anticancer therapy and its excellent performance in complex sample matrices add significant value to the field of electrochemical sensing for pharmaceutical analysis.

The purpose of this paper is to design novel tunnel field effect transistor (TFET) using graphene nanoribbons (GNRs).

To design the proposed TFET, the bilayer GNRs (BLGNRs) have been used as the channel material. The BLGNR-TFET is designed in QuantumATK, depending on 2-D Poisson’s equation and non-equilibrium Green’s function (NEGF) formalism.

The performance of the proposed BLGNR-TFET is investigated in terms of current and voltage (I-V) characteristics and transconductance. Moreover, the proposed device performance is compared with the monolayer GNR-TFET (MLGNR-TFET). From the simulation results, it is investigated that the BLGNR-TFET shows high current and gain over the MLGNR-TFET.

This paper presents a new technique to design GNR-based TFET for future low power very large-scale integration (VLSI) devices.

This paper aims to develop an inexpensive, portable, sensitive and environmentally friendly electrochemical sensor to quantify trace metals.

A sensor was constructed by modifying carbon paste electrode for the determination of lead, cadmium and zinc ions using square wave anodic stripping voltammetry (SWASV). The modified electrode was prepared by inserting homogeneous mixture of 2-hydroxy-acetophenonethiosemicarbazone, graphite powder and mineral oil. Various important parameters controlling the performance of the sensor were investigated and optimized. Electrochemical behavior of modified electrode was characterized by cyclic voltammetry.

Modified carbon pastes electrodes showed three distinct peaks at −0.50, −0.76 and −1.02 V vs silver/silver chloride corresponding to the oxidation of lead, cadmium and zinc ions at the electrode surface, respectively. The highest peak currents for all the metal ions under study were observed in the phosphate buffer solution at pH 1 with a deposition time of 70 s. The sensor exhibited linear behavior in the range of 0.25-12.5 μg mL-1 for lead and cadmium and 0.25-10.0 μg mL⁻¹ for zinc. The limit of detection was calculated as 78.81, 96.17 and 91.88 ng mL⁻¹ for Pb2⁺, Cd2⁺and Zn2⁺, respectively. The modified electrode exhibited good stability and repeatability.

A chemically modified electrode with Schiff base was applied to determine the content of cadmium, lead and zinc ions in aqueous solutions using SWASV.

The purpose of this study is to study the mechanical, tribological and electrical properties of the copper-graphene (Cu-Gn) composites fabricated by a novel rapid tooling technique consist of three-dimensional printing and ultrasonic-assisted pressureless sintering (UAPS).

Four different Cu-Gn compositions with 0.25, 0.5, 1 and 1.5 per cent of graphene were fabricated using an amalgamation of three-dimensional printing and UAPS. The polymer 3d printed parts were used to prepare mould cavity and later the UAPS process was used to sinter Cu-Gn powder to acquire free-form shape. The density, hardness, wear rate, coefficient of friction and electrical conductivity were evaluated for the different compositions of graphene and compared with the pure copper. Besides, the comparison was performed with the conventional method.

Cu-Gn composites revealed excellent wear properties due to higher hardness, and the lubrication provided by the graphene. The electrical conductivity of the fabricated Cu-Gn composites started increasing initially but decreased afterwards with increasing the content of graphene. The UAPS fabricated composites outperformed the conventional method manufactured samples with better properties such as density, hardness, wear rate, coefficient of friction and electrical conductivity due to homogeneous mixing of metal particles and graphene.

The fabrication of Cu-Gn composite freeform shapes was found to be difficult using conventional methods. The novel technique using a combination of polymer three-dimensional printing and UAPS as rapid tooling was introduced for the fabrication of freeform shapes of Cu-Gn composites and mechanical, tribological and electrical properties were studied. The method can be used to fabricate optimized complex Cu-Gn structures with improved wear and electrical applications.

The purpose of this paper is to present the properties of thick-film resistors made of novel pastes prepared from glass and graphite.

Graphite-based resistors were made of thick-film pastes with different graphite-to-glass mass fraction were prepared and examined. Sheet resistance, temperature coefficient of resistance, impact of humidity and short-term overload were investigated. The properties of the layers fired in atmospheres of air at 550°C and nitrogen at 875°C were compared.

Graphite-based resistors with various graphite-to-glass ratios made possible to obtain a wide range of sheet resistance from single O/square to few kO/square. These values were dependent on firing atmosphere, paste composition and the number of screen-printed layers. The samples made of paste with 1:1 graphite-to-glass ratio exhibited the temperature coefficient of resistance of about −1,000 ppm/°C, almost independently on the firing atmosphere and presence of a top coating. The resistors fired in the air after coating with overglaze, exhibited significantly lower sheet resistance, reduced impact of humidity and improved power capabilities.

In this paper, graphite-based resistors for applications in typical high-temperature cermet thick-film circuits were presented, whereas typical graphite-based resistors were fabricated in polymer thick-film technology. Owing to very low cost of the graphite, the material is suitable for low-power passive circuits, where components are not subjected into high temperature, above the typical temperature of operation of standard electronic components.