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1 – 10 of 304Piotr Walter, Andrzej Pepłowski, Łukasz Górski, Daniel Janczak and Małgorzata Jakubowska
Because of the bioaccumulation effect, organophosphorus pesticides cause long-term damage to mammals, even at small concentrations. The ability to perturb the phospholipid bilayer…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Originality/value
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.
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Kazimierz Drabczyk and Piotr Panek
The paper aims to present results of investigations carried out on the front electrode of the solar cell. The front-side electrode for solar cells based on crystalline material is…
Abstract
Purpose
The paper aims to present results of investigations carried out on the front electrode of the solar cell. The front-side electrode for solar cells based on crystalline material is obtained by the screen printing method. Screen printing has been the prevailing method of electrode deposition because of its low cost. One of the ways to improve the cell efficiency and reduce the production costs is a further refinement of the metal electrode screen printing process.
Design/methodology/approach
The researches were focused on the modification of mechanical parameters of screen printing process to ensure the best possible cross-section of the front electrode geometry. The main printing process parameters were constant, however, the print speed was variable. The obtained fine line of front contact was characterized morphologically – the dimension and geometry of the front contact cross-section – by scanning electron microscopy technique.
Findings
The thin paths of 100 μm in width were screen printed applying a new silver-paste made by Du Pont. The printing speed has significant effect on print quality in the way that the lower speed enhanced the printed results.
Research limitations/implications
For newest pastes (e.g. PV17D) influence of screen printing parameters on the front metallic electrodes geometry of solar cell is not so significant. Presented screen printing process can still give good results, but the further optimization for the new paste must be performed to achieve better cross-section geometry.
Originality/value
This paper confirms that one-step screen printing process can still give good results. The screen printed thin paths of 100 μm in width have good cross-section aspect ratio.
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In this paper, results of the studies on the copper deposition on screen-printed fine-line front electrode of the solar cell were presented. The silver consumption is an important…
Abstract
Purpose
In this paper, results of the studies on the copper deposition on screen-printed fine-line front electrode of the solar cell were presented. The silver consumption is an important problem according to growing silver prices. The proposed solution of those problems might be printing of a very thin silver seed layer and subsequent copper plating. This process can be an alternative for typically used screen printing. The purpose of this study was the optimization of the finger path fabrication process to obtain required geometric of fingers for copper deposition.
Design/methodology/approach
In this paper, double-step metallization process was analyzed. The first step of an electrode formation is screen printing, the second one is copper electrodeposition. Presented investigations were focused on the optimization of the finger path fabrication process to obtain required geometric dimensions and sharp border of fingers. The morphology of the electrodes was characterized by scanning electron microscope before and after copper deposition. The X-ray analysis of elemental arrangement and cross-section profiles of fingers were made using energy-dispersive X-ray fluorescence spectrometer.
Findings
Presented investigations were focused on the optimization of the finger path fabrication process to obtain required geometric dimensions and sharp border of fingers without any silver particles. The main problem of non-uniform silver paste distribution close to the border of printed finger paths was eliminated by selection of appropriate paste and printing parameters. The obtained coatings were soft, ductile and bright.
Originality/value
The novelty of the presented approach is modification of the printing parameters, especially for copper deposition. In this paper, the reasons of the widening of electrodes during the copper deposition process is analyzed.
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Eduardo Garcia-Breijo, Gema Prats-Boluda, Jose Vicente Lidon-Roger, Yiyao Ye-Lin and Javier Garcia-Casado
This paper aims to present a comparison between three types of manufacturing techniques, namely, screen-printed, inkjet and gravure, using different types of inks, for the…
Abstract
Purpose
This paper aims to present a comparison between three types of manufacturing techniques, namely, screen-printed, inkjet and gravure, using different types of inks, for the implementation of concentric ring electrodes which permit estimation of Laplacian potential on the body surface.
Design/methodology/approach
Flexible concentric ring electrodes not only present lower skin–electrode contact impedance and lower baseline wander than rigid electrodes but are also less sensitive to interference and motion artefacts. The above three techniques allow printing of conductive inks on flexible substrates, and with this work, the authors aim to study which is the best technique and ink to obtain the best electrode response.
Findings
From the results obtained regarding ink thickness, resistivity, electrode resistance and other performance parameters derived from electrocardiographic signal recording tests, it can be said that concentric electrodes using the screen-printing and inkjet techniques are suitable for non-invasive bioelectric signal acquisition.
Originality/value
The development of new types of inks and substrates for the electronics industry and the adaptation of new manufacturing techniques allow for an improvement in the development of electrodes and sensors.
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Kazimierz Drabczyk, Jaroslaw Domaradzki, Grazyna Kulesza-Matlak, Marek Lipinski and Danuta Kaczmarek
The purpose of this paper was investigation and comparison of electrical and optical properties of crystalline silicon solar cells with ITO or TiO2 coating. The ITO, similar to TiO…
Abstract
Purpose
The purpose of this paper was investigation and comparison of electrical and optical properties of crystalline silicon solar cells with ITO or TiO2 coating. The ITO, similar to TiO2, is very well transparent in the visible part of optical radiation; however, its low resistivity (lower that 10-3 Ohm/cm) makes it possible to use simultaneously as a transparent electrode for collection of photo-generated electrical charge carriers. This might also invoke increasing the distance between screen-printed metal fingers at the front of the solar cell that would increase of the cell’s active area. Performed optical investigation showed that applied ITO thin film fulfill standard requirements according to antireflection properties when it was deposited on the surface of silicon solar cell.
Design/methodology/approach
Two sets of samples were prepared for comparison. In the first one, the ITO thin film was deposited directly on the crystalline silicon substrate with highly doped emitter region. In the second case, the TCO film was deposited on the same type of silicon substrate but with additional ultrathin SiO2 passivation. The fingers lines of 80 μm width were then screen-printed on the ITO layer with two different spaces between fingers for each set. The influence of application of the ITO electrode and the type of metal electrodes patterns on the electrical performance of the prepared solar cells was investigated through optical and electrical measurements.
Findings
The electrical parameters such as short-circuit current (Jsc), open circuit voltage (Voc), fill factor (FF) and conversion efficiency were determined on a basis of I-V characteristics. Short-circuit current density (Jsc) was equal to 32 mA/cm2 for a solar cell with a typical antireflection layer and 31.5 mA/cm2 for the cell with ITO layer, respectively. Additionally, electroluminescence of prepared cells was measured and analysed.
Originality/value
The influence of the properties of ITO electrode on the electrical performance of crystalline silicon solar cells was investigated through complex optical, electrical and electroluminescence measurements.
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Katarina Cvejin, Libu Manjakkal, Jan Kulawik, Krzysztof Zaraska and Dorota Szwagierczak
– This paper aims to investigate different properties of synthesized perovskite Sm0.9Sr0.1CoO3-δ and its potential for application in potentiometric oxygen sensors.
Abstract
Purpose
This paper aims to investigate different properties of synthesized perovskite Sm0.9Sr0.1CoO3-δ and its potential for application in potentiometric oxygen sensors.
Design/methodology/approach
The powder was obtained through solid-state reaction method and characterized by thermogravimetric/differential thermal analyzer and X-ray diffraction. It was used for both making a paste and pressing into rods for sintering. The prepared paste was deposited on alumina and yttria-stabilized zirconia substrates, by screen printing. Thick film conductivity, bulk conductivity and Seebeck coefficient of sintered rods were measured as a function of temperature. An oxygen concentration cell was fabricated with the screen-printed perovskite material as electrodes.
Findings
Electrical conductivity of the bulk sample and thick film increases with the increase in temperature, showing semiconductor-like behavior, which is also indicated by relatively high values of the measured Seebeck coefficient. Estimated values of the activation energy for conduction are found to be of the same magnitude as those reported in the literature for similar composition. An investigation of Nernstian behavior of the fabricated cell confirmed that Sm0.9Sr0.1CoO3-δ is a promising material for application in oxygen potentiometric sensors.
Originality/value
Gas sensor research is focused on the development of new sensitive materials. Although there is scarce information on SmCoO3-δ in the literature, it is mostly investigated for fuel cell applications. Results of this study imply that Sr-doped SmCoO3-δ is a good candidate material for oxygen potentiometric sensor.
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J.K. Atkinson, M. Glanc, P. Boltryk, M. Sophocleous and E. Garcia‐Breijo
The purpose of this paper is to show how the fabrication parameters of screen‐printed thick‐film reference electrodes have been experimentally varied and their effect on device…
Abstract
Purpose
The purpose of this paper is to show how the fabrication parameters of screen‐printed thick‐film reference electrodes have been experimentally varied and their effect on device characteristics investigated.
Design/methodology/approach
The tested devices were fabricated as screen‐printed planar structures consisting of a silver back contact, a silver/silver chloride interfacial layer and a final salt reservoir layer containing potassium chloride. The fabrication parameters varied included deposition method and thickness, salt concentration and binder type used for the final salt reservoir layer. Characterisation was achieved by monitoring the electrode potentials as a function of time following initial immersion in test fluids in order to ascertain initial hydration times, subsequent electrode drift rates and useful lifetime of the electrodes. Additionally, the effect of fabrication parameter variation on electrode stability and their response time in various test media was also investigated.
Findings
Results indicate that, although a trade‐off exists between hydration times and drift rate that is dependent on device thickness, the initial salt concentration levels and binder type also have a significant bearing on the practical useful lifetime. Generally speaking, thicker devices take longer to hydrate but have longer useful lifetimes in a given range of chloride environments. However, the electrode stability and response time is also influenced by the type of binder material employed for the final salt reservoir layer.
Originality/value
The reported results help to explain better the behaviour of thick‐film reference electrodes and contribute towards the optimisation of their design and fabrication for use in solid‐state chemical sensors.
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W.V. Glasspool and J.K. Atkinson
The bulk batch fabrication process of thick film technology has been utilised in the design and production of miniature amperometric dissolved oxygen sensors based on…
Abstract
The bulk batch fabrication process of thick film technology has been utilised in the design and production of miniature amperometric dissolved oxygen sensors based on potentiostatic and voltammetric operation. Three different polymers have been investigated as membrane materials – cellulose acetate, PTFE and PVC. PTFE has been deposited on the devices by aerosol spray and PVC and cellulose acetate by screen‐printing. These methods have been shown to be effective membrane fabrication techniques, and have significant implications in the field of chemical sensors as a whole. All the membrane covered devices investigated were found to exhibit sensitive and linear responses to dissolved oxygen. The effects of temperature and flow rate on sensor response have been investigated and the use of PVC and PTFE in place of cellulose acetate have been shown to reduce both effects. These membranes have also been shown to reduce the detrimental effects of fouling observed on the surfaces of cellulose acetate covered devices as they are powered in tap water.
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Kazimierz Drabczyk, Edyta Wróbel, Grazyna Kulesza-Matlak, Wojciech Filipowski, Krzysztof Waczynski and Marek Lipinski
The purpose of this study is comparison of the diffusion processes performed using the commercial available dopant paste made by Filmtronics and the original prepared liquid…
Abstract
Purpose
The purpose of this study is comparison of the diffusion processes performed using the commercial available dopant paste made by Filmtronics and the original prepared liquid dopant solution. To decrease prices of industrially produced silicon-based solar cells, the new low-cost production processes are necessary. The main components of most popular silicon solar cells are with diffused emitter layer, passivation, anti-reflective layers and metal electrodes. This type of cells is prepared usually using phosphorus oxychloride diffusion source and metal pastes for screen printing. The diffusion process in diffusion furnace with quartz tube is slow, complicated and requires expensive equipment. The alternative for this technology is very fast in-line processing using the belt furnaces as an equipment. This approach requires different dopant sources.
Design/methodology/approach
In this work, the diffusion processes were made for two different types of dopant sources. The first one was the commercial available dopant paste from Filmtronics and the second one was the original prepared liquid dopant solution. The investigation was focused on dopant sources fabrication and diffusion processes. The doping solution was made in two stages. In the first stage, a base solution (without dopants) was made: dropwise deionized (DI) water and ethyl alcohol were added to a solution consisting of tetraethoxysilane (TEOS) and 99.8 per cent ethyl alcohol. Next, to the base solution, orthophosphoric acid dissolved in ethyl alcohol was added.
Findings
Diffused emitter layers with sheet resistance around 60 Ω/sq were produced on solar grade monocrystalline silicon wafers using two types of dopant sources.
Originality/value
In this work, the diffusion processes were made for two different types of dopant sources. The first one was the commercial available dopant paste from Filmtronics and the second one was the original prepared liquid dopant solution.
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Keywords
Abstract
The present and potential applications of screen‐printing thick film technology to the field of chemical sensing are briefly reviewed in the first part of the paper. The second part is devoted to the search for new routes to selectivity for basically non‐selective gas sensors.