Three dimensional structures made of sugar based materials can be utilized in tissue engineering since sugar serves as a nutrient for growing cells. It can also be applied in other areas of life like food industry or art. Following paper describes preparation of a material based on commonly used sucrose and proteins contained in chicken eggs. Furthermore a method of additive manufacturing with use of the mentioned material is also described. Method is based on a direct write 3D printing technology and was implemented by utilizing a low cost commercial 3D printer alongside with an industrial glue dispenser. The printed parts are then dried using UV light or a common oven and presented results are discussed.
See-through layers of conductive material are used in many fields of science and technology for example on screens of electronic devices or heated car windows. An elaboration of a high-performance and economical method of producing transparent electrodes is one of the challenges of today's science. This paper presents the results of spraying test of various conductive inks, performed on an ultrasonic spray coating station, leading to a development the optimal parameters of manufacturing the transparent conductive electrode. Spray coating is one of the most common techniques of coating objects with thin films. The ultrasonic atomization used in this process allows the increase of the precision and thus decrease of thickness and higher homogeneity of applied layers. In this study, after the selection of the best carrier and coating parameters, a suspension of carbon nanotubes was created and used for coating. The prepared sample was subjected to electrical tests and the results of these studies have been described.
Aerosol jet printing is a new technology which is able to form a micrometer size patterns directly on the substrate. It is possible due to the special ink treatment - first, the ink is formulated to form a mist or fog with a very small droplets (average size about 1 μm). Then the atomized ink is transported to the printing head. In the printing head, a special shear gas flow focuses the mist into several micrometer size stream. This technology is an additive method which allows printing even on the 3D substrates. The achievement of 10 μm line wide makes it comparable with conventional flat, many stages photolithography. In this article, authors present the self-made printing head for the aerosol jet method and the results of the printing process. The printing process was performed with ultrasonic atomizer and the nanosilver ink. As a result, authors have obtained conductive, 40 μm wide silver lines.
Printing electronics even though the printing techniques are known for a long time, are gaining in importance. The possibility of making the electronic circuits on flexible, big-area substrates with efficient and cheap technology make it attractive for the electronic industry. Spray coating, as a one of printing methods, additionally provide the chance to print on the non-flat, complicated shaped substrates. Despite the spray coating is mostly used to print a big pads, it is reachable to spray the separate conductive lines both as a quickly-produced prototype and as a fully manufactured circuit. Our work presents the directly printed lines with spray coating technique. For the printing process self-made ink was used. We tested three different approaches to line formation and compare them in the terms of line edge, resistivity and thickness. Line profiles provide the information about the roughness and the line size. In the end we showed the aerosol jet printed meander to give an overview of this similar to spray coating but more sophisticated technique.
In the last few years there has been a growing interest in wearable electronic products, which are generating considerable interest especially in sport and medical industries. But rigid electronics is not comfortable to wear, so things like stretchable substrates, interconnects and electronic devices might help. Flexible electronics could adjust to the curves of a human body and allow the users to move freely. The objective of this paper is to study possibilities of polymer composites with conductive nanomaterials application in wearable electronics. Pastes with graphene, silver nanoplates and carbon nanotubes were manufactured and then interconnects were screen-printed on the surfaces of polyethylene terephthalate (PET) and fabric. Afterwards, the resistance and mechanical properties of samples were examined, also after washing them in a washing machine. It has been found that the best material for the conductive phase is silver. Traces printed directly on the fabric using conductive composites with one functional phase (silver nanoplates or graphene or carbon nanotubes) are too fragile to use them as a common solution in wearable electronics. Mechanical properties can be improved not only by adding carbon nanotubes or graphene to the silver paste, but also by printing additional layer of graphene paste or carbon nanotube paste onto silver layer. In fact, these solutions are not sufficient enough to solve a problem of using these composites in wearable electronics.
Electrodes for measuring pH of the solution were fabricated by the means of screen-printing technology. Potentiometric sensors’ layers comprised of composite with polymer matrix and graphene nanoplatelets/ruthenium (IV) oxide nanopowder as functional phase. Transceivers were printed on the elastic PMMA foil. Regarding potential application of the sensors in the wearable devices, dynamic response of the electrodes to changing ultraviolet radiation levels was assessed, since RuO2 is reported to be UV-sensitive. Observed changes of the electrodes’ potential were of sub-millivolt magnitude, being comparable to simultaneously observed signal drift. Given this stability under varying UV conditions and previously verified good flexibility, fabricated sensors meet the requirements for wearable applications.
Thin composite layers based on polyacrylonitrile (PAN) and carbon nanotubes (CNT) were fabricated by means of spray coating with pneumatic atomization. Research was conducted to achieve transparent and flexible electrodes. Prepared suspensions in different proportions of functional phase provided good dispersion quality of CNTs and the stability. The carbon nanotubes were dispersed in dimethylformamide and then added to polyacrylonitrile solution. Suspension was sprayed onto Polyethylene terephthalate (PET) foil. After thermal treatment, samples were mechanically and electrically tested. Thanks to carbon nanomaterials used in prepared coatings, high electrical conductivity and mechanical resistance was observed. Use of a polyacrylonitrile guarantee the flexibility of electrodes and high potential in integration with polyacrylonitrile based fabrics.
Transparent electrodes are one of the basic elements of various electronic components. The paper presents the preliminary results related to novel method of ultrasonic spray coating used for fabrication of transparent flexible electrodes. Experiments were conducted by means of specially made laboratory setup composed of ultrasonic spray generator and XYZ plotter. In the first part of the paper diverse solvents were used to determine the crucial technological parameters such as atomization voltage and fluid flow velocity. Afterwards paint containing carbon nanotubes suspended in the two solvent system was prepared and deposited on the polyethylene terephthalate foil. Thickness, roughness and electrical measurements were performed to designate the relations of technological parameters of ultrasonic spray coating on thickness, roughness, sheet resistance and optical transmission of fabricated samples.
The purpose of the work is to find an appropriate flexible material to replace commonly used transparent conductive oxides (TCO) in photovoltaic (PV) emitter electrode applications. Authors show the alternative, potential possibility of using PEDOT conductive polymer as transparent emitter contacts for thin-film, flexible photovoltaic structures. The vast majority of contacts made of TCO layers, dominantly indium tin oxide ITO, are electrically unstable under the influence of mechanical stresses [1,2,3]. This drawback inhibits their usage in flexible devices, such as solar cells. The need of the development in the field of flexible PV structures induces searching for new materials. Investigated transparent conductive layers (TCL) were made of organic compositions based on PEDOT polymer and their parameters were compared with equally measured parameters of carbon nanotube (CNT) layers, commercial ITO and AgHT ultra-thin silver layers. Transparent conductive layers based on PEDOT:PSS compound were deposited on flexible substrates by screen printing technique. The analysis of achieved results shows the broad spectrum of application possibilities for PEDOT layers.
Carbon nanotubes as well as graphene are allotropic forms of carbon. Graphene is a two dimensional (2D) form of atomic-scale, hexagonal lattice, while carbon nanotube is a cylindrical nanostructure composed of a rolled sheet of graphene lattice at specific and discrete angles.
Both of discussed materials have a high potential for modern engineering, especially in organic and printed electronics. High transparency in the visible part of the electromagnetic spectrum and low electrical resistance are desirable features in various applications and may be fulfilled with studied carbon nanomaterials. They have chances to become an important technological improvement in customers electronic devices by applying them to electrodes production in flexible screens and light sources.
Graphene end carbon nanotubes are conceptually similar. However, characteristic properties of these two substances are different. In the article authors present the results of the transmission in visible electromagnetic spectrum characteristics of different samples. This parameter and the resistance of electrodes are tested, analysed and compared. Characteristics of optical transmittance against resistance with the optimal point of that relationship are presented in paper. Moreover, dependency of graphene nanoplatelets agglomerates arrangement against type of nano-fillers is shown.
Two groups of tested inks contain graphene nanoplatelets with different fillers diameters. The third group contains carbon nanotubes.
Described parameters are important for production process and results of analysis can be used by technologists working with elastic electronics.
In the thick film technology it is very important that paste can be printed easily on the substrate and that printed pattern is correct and precise. Paste printing behavior is characterized by its rheology. The main aim of this work was to examine the influence of paste composition on the rheology of pastes containing graphene nanoplatelts. The secondary aim was to find the optimal composition of the pastes. The resulting measurements graphs of viscosity curves shows the influence of: binder type, functional phase content, dispersant type and content on the rheological properties of polymer pastes. The thicknesses of printed layers, obtained from pastes which characterized by various viscosity, were measured. At the end composition of the pastes with graphene nanoplatelets that exhibit the best rheological properties was described.
Graphene nanoplatelets exhibit high potential for current engineering applications, particularly in context of conductive inks for organic and flexible electronic. Electrodes for organic displays are expected to be transparent in the visible part of electromagnetic spectrum.
Thus this study aimed at full-field transmission measurements in the visible wavelength range. The paper presents transmission characteristics of different graphene samples. Samples, prepared using spray coating methods contained 3 types of deposited inks. Each of them was based on different concentration and size of graphene nanoplatelets. Moreover, they had various numbers of layers. Such materials were characterized by different parameters, like distribution of deposited carbon nanoparticles which is influencing layers homogeneity, resulting in different optical properties.
Further, this research tries to establish a robust indicators characterizing examined samples. Authors built in Institute novel scanning optical system with fiber-based, compact spectrometer instead of other expensive techniques used for material characteristic in nanosciences i.e. high-resolution scanning electron microscopy. An optical scheme, design of system and technical parameters are described.
Performed examinations show, that number of parameters derived from our measurements, strongly correlate with physical properties of deposited inks. Authors estimated surface roughness, homogeneity and distribution of nanoparticles agglomerates within the deposited layers.
Presented results suggest, that this novel cost-effective, simple optical method of materials characterization especially in production of graphene nanoplates coatings can be promising in concern of repeatability assessment and optical properties.
Optical coherence tomography (OCT) is noncontact and nondestructive interferometric method which allows visualization of internal structure of an investigated sample. Till now it has found many applications in measurements of biological tissues, technical materials and conservation of art. Optical coherence tomography in full-field configuration is a great technique for visualization of subsurface structures of measured sample with high resolution. In this technique, en-face data acquisition is applied, which allows application of microscope objectives with high numerical aperture while the depth of field is not a problem. These objectives allow obtaining ultra high transverse resolution like in traditional microscopy. Additionally, light sources with broad spectrum, like low cost incandescent lamps (i.e. halogen lamp), allow measurements with micrometer scaleaxial resolution. In this paper the authors present application of full-field optical coherence tomography with a Linnik microscope for the thickness measurement of layers in flexible display with electrodes made of graphene and carbone nanotubes. Thicknesses of layer have a huge impact on the display parameters. There is a correlation between the thickness of the graphene layer and its electrical resistance. Graphene is a new and very promising material which is durable, flexible and has a good adhesion to diverse substrates. It gives a theoretical possibility to create flexible electronics, such as graphene bendable screens. Using OCT we can evaluate the quality of printed layers and detect subsurface defects.
Polymer substrates which are covered with a thin layer of graphene nanoplatelets or carbon nanotubes have a big potential for modern engineering, especially in organic electronics. The main advantage of those materials is transparency in the visible part of the electromagnetic spectrum. This property creates a possibility of using these materials to produce electrodes in flexible screens and light sources. It is necessary to know the transmission characteristics of these materials to assess their usefulness in optoelectronics. In the article authors present the results of the conducted research on the transmittance characteristics of different samples. The samples contained different deposited substances. They had various diameters of the graphene nanoplatelets, one group contained carbon nanotubes. Samples had 50 or 100 layers. The authors examine the influence of these parameters on ink transmittance and ink transmittance uniformity. These analyses are a base for future research on flexible carbon electrodes, especially for applying them in production of flexible organic displays and light sources.
Transparent, flexible and conducting graphene films were produced by screen printing method using printing pastes
based on graphene nanoplatelets in polymer matrix. The transparency of received layers and the mechanical resistivity in
several bending cycles were measured. Subsequently percolation threshold was investigated. Graphene layers were
printed on diverse substrates (glass, Al2O3, PET) and afterwards for samples printed on glass different firing atmospheres
(N2, H2, air) were studied. Best firing results (resistance decrease) were obtained for treatment in 250 °C in atmosphere
of air. Finally investigation results were used to produce a transparent and elastic electrode for an electroluminescent
display, showing the application potential of our graphene nanocomposite pastes.
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