scholarly journals Advanced Manufacture by Screen Printing

2020 ◽  
Author(s):  
◽  
Sarah-Jane Potts
Keyword(s):  
Screen Printing ◽  
Computational Models ◽  
Printed Electronics ◽  
Low Cost ◽  
Solid Loading ◽  
Wide Range ◽  
Parametric Studies ◽  
Ink Transfer ◽  
First Time ◽  
Carbon Inks

Screen-printing is the most widely used process in printed electronics, due to its ability to transfer materials with a wide range of functional properties at high thickness and solid loading. However, the science of screen printing is still rooted in the graphics era, with limited understanding of the fundamental science behind the ink transfer process. A multifaceted approach encompassing all aspects of the production of printed electronics from ink formulation, through screen-printing and post processing was therefore undertaken. With a focus on carbon inks due to their electrical conductivity, low cost, inertness and ability to be modified or functionalised. Parametric studies found that with blade squeegees, lower angles and softer blades led to increases in ink deposition, irrespective of ink rheology. However, the effects of print speed and snap distance were related to the rheology of the inks. Existing computational models were inaccurate and based on two contrasting theories. Extensional CaBER testing provided qualitative indications of the effect of separation speed and distance on deposition. However, this could only assess the effect of vertical, 2-dimensional forces and could not evaluate the influence of shear forces due to separation angle or the effects of the screen mesh. For this purpose, a screen-printing visualisation rig was specifically constructed, allowing the ink transfer mechanism to be captured for the first time. This identified similarities with one of the two theories, although existing models had oversimplified the process and did not account for variations in lengths of the separation regions or the contact angle between the mesh and substrate. It was also found that changes in the ink rheology and parameter settings changes the lengths of these regions, as well as the shape and presence of filaments formed during separation. The parameters of print speed, snap distance, solid loading and ink rheology were assessed and found to affect the mesh/substrate contact time and filamentation behaviour. This had a quantifiable effect on ink deposition, in terms of the amount of ink transfer, roughness and therefore conductivity. Finally, photonic annealing and subsequent compression rolling were found to enhance the conductivity of carbon inks by removing binder between particles and consolidating the ink film, leading to 8 times reduction in resistivity for a graphite-based ink and halving in resistivity for an ink containing a combination of carbon black and graphite, where there was less potential for improvement due to the conductive bridges between the graphite flakes.

scholarly journals High-speed imaging the effect of snap-off distance and squeegee speed on the ink transfer mechanism of screen-printed carbon pastes

2019 ◽  
Vol 17 (2) ◽  
pp. 447-459 ◽  
Author(s):  
Sarah-Jane Potts ◽  
Chris Phillips ◽  
Eifion Jewell ◽  
Ben Clifford ◽  
Yin Cheung Lau ◽  
...  
Keyword(s):  
High Speed ◽  
Screen Printing ◽  
Printed Electronics ◽  
Functional Materials ◽  
Print Quality ◽  
High Speed Imaging ◽  
Predictive Algorithms ◽  
Wide Range ◽  
And Performance ◽  
Ink Transfer

AbstractScreen printing is the most widely used process in the production of printed electronics due to its ability to consistently transfer inks containing a wide range of functional materials onto a range of substrates. However, despite its extensive use, the mechanism by which the ink is transferred through the mesh and onto the substrate is not fully understood. Existing theories are contradictory and lack experimental validation. Therefore, high-speed imaging was used in combination with a screen-printing simulation rig that was designed to provide good optical access to study ink deposition during the screen-printing process. The variation in the four stages of ink flow through the screen, described in the theory by Messerschmitt, has been quantified with respect to changes in snap-off distance and squeegee speed. Analyses of the images were compared with measurements of the ink properties and corroborated with analyses of the prints. This has provided a better understanding of the mechanism by which the ink transfers from the mesh to the substrate and subsequently separates in screen printing. This could be used as the basis for the development of predictive algorithms, as well as to improve the understanding of how to optimize print quality and performance.

scholarly journals The effect of plasma functionalization on the print performance and time stability of graphite nanoplatelet electrically conducting inks

2020 ◽  
Author(s):  
Andrew Claypole ◽  
James Claypole ◽  
Tim Claypole ◽  
David Gethin ◽  
Liam Kilduff
Keyword(s):  
Printed Electronics ◽  
Low Cost ◽  
Electrical Performance ◽  
Graphite Nanoplatelets ◽  
Interparticle Interactions ◽  
Electrically Conducting ◽  
Wide Range ◽  
Oscillatory Rheology ◽  
The Stability ◽  
Plasma Functionalization

Abstract Carbon-based pastes and inks are used extensively in a wide range of printed electronics because of their widespread availability, electrical conductivity and low cost. Overcoming the inherent tendency of the nano-carbon to agglomerate to form a stable dispersion is necessary if these inks are to be taken from the lab scale to industrial production. Plasma functionalization of graphite nanoplatelets (GNP) adds functional groups to their surface to improve their interaction with the polymer resin. This offers an attractive method to overcome these problems when creating next generation inks. Both dynamic and oscillatory rheology were used to evaluate the stability of inks made with different loadings of functionalized and unfunctionalized GNP in a thin resin, typical of a production ink. The rheology and the printability tests showed the same level of dispersion and electrical performance had been achieved with both functionalized and unfunctionalized GNPs. The unfunctionalized GNPs agglomerate to form larger, lower aspect particles, reducing interparticle interactions and particle–medium interactions. Over a 12-week period, the viscosity, shear thinning behavior and viscoelastic properties of the unfunctionalized GNP inks fell, with decreases in viscosity at 1.17 s−1 of 24, 30, 39% for the ϕ = 0.071, 0.098, 0.127 GNP suspensions, respectively. However, the rheological properties of the functionalized GNP suspensions remained stable as the GNPs interacted better with the polymer in the resin to create a steric barrier which prevented the GNPs from approaching close enough for van der Waals forces to be effective.

scholarly journals Low-Cost Microfabrication Tool Box

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 135 ◽  
Author(s):  
Charmet ◽  
Rodrigues ◽  
Yildirim ◽  
Challa ◽  
Roberts ◽  
...  
Keyword(s):  
Mass Production ◽  
Screen Printing ◽  
Low Cost ◽  
Unit Cost ◽  
Functional Materials ◽  
Technological Advances ◽  
Wide Range ◽  
In Vitro Diagnostic ◽  
Key Enabling Technologies

Microsystems are key enabling technologies, with applications found in almost every industrial field, including in vitro diagnostic, energy harvesting, automotive, telecommunication, drug screening, etc. Microsystems, such as microsensors and actuators, are typically made up of components below 1000 microns in size that can be manufactured at low unit cost through mass-production. Yet, their development for commercial or educational purposes has typically been limited to specialized laboratories in upper-income countries due to the initial investment costs associated with the microfabrication equipment and processes. However, recent technological advances have enabled the development of low-cost microfabrication tools. In this paper, we describe a range of low-cost approaches and equipment (below £1000), developed or adapted and implemented in our laboratories. We describe processes including photolithography, micromilling, 3D printing, xurography and screen-printing used for the microfabrication of structural and functional materials. The processes that can be used to shape a range of materials with sub-millimetre feature sizes are demonstrated here in the context of lab-on-chips, but they can be adapted for other applications. We anticipate that this paper, which will enable researchers to build a low-cost microfabrication toolbox in a wide range of settings, will spark a new interest in microsystems.

scholarly journals Investigation of Carbon-Based Composites for Elastic Heaters and Effects of Hot Pressing in Thermal Transfer Process on Thermal and Electrical Properties

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7606
Author(s):  
Tomasz Raczyński ◽  
Daniel Janczak ◽  
Jerzy Szałapak ◽  
Piotr Walter ◽  
Małgorzata Jakubowska
Keyword(s):  
Flexible Electronics ◽  
Hot Pressing ◽  
Screen Printing ◽  
Printed Electronics ◽  
Wearable Electronics ◽  
Thermal Transfer ◽  
Wide Range ◽  
Thermal And Electrical Properties ◽  
Carbon Based ◽  
Screen Printed

Wearable electronics are new structures with a wide range of possible applications. This study aims to analyze the effects of hot pressing in thermal transfer of different carbon-based composites as a new application method of screen-printed electronics on textiles. Flexible heaters were screen-printed on polyethylene terephthalate PET foil with composites based on graphene, carbon black, and graphite with different wt.%, measured and then hot pressed to measure and analyze differences. Research showed that the hot pressing process in thermal transfer resulted in decreased electrical resistance, increased power, and higher maximal temperatures. Best results were achieved with composites based on 12 wt.% graphene with sheet resistance lowered by about 40% and increased power by about 110%. This study shows promise for thermal transfer and screen-printing combination as an alternative for creating flexible electronics on textiles.

Nanocellulose based carbon ink and its application in electrochromic displays and supercapacitors.

2021 ◽  
Author(s):  
Robert Brooke ◽  
Andreas Fall ◽  
Mateu Borràs ◽  
Dagmawi Belaineh ◽  
Jesper Edberg ◽  
...  
Keyword(s):  
Screen Printing ◽  
Printed Electronics ◽  
Cellulose Nanofibrils ◽  
Current Collector ◽  
Manufacturing Processes ◽  
Electronic Manufacturing ◽  
Significant Interest ◽  
Commercial Carbon ◽  
Screen Printing Technology ◽  
Carbon Inks

Abstract Conventional electronics have been highlighted as an unsustainable technology; hazardous wastes are produced both during their manufacturing but also, due to their limited recyclability, during electronic end of life cycle (e.g., disposal in landfill). In recent years additive manufacturing processes have attracted significant interest as a more sustainable approach to electronic manufacturing. Despite the field of printed electronics addressing some of the issues related to the manufacturing of electronics, many components and inks are still considered hazardous to the environment and are difficult to recycle. Here we present the development of a low environmental impact carbon ink based on a non-hazardous solvent and a cellulosic matrix and its implementation in electrochromic displays and supercapacitors. As part of the reported work, a different protocol for mixing carbon and cellulose nanofibrils (CNF) (rotation mixing and high shear force mixing), nanocellulose of different grades and different carbon: nanocellulose ratio were investigated and optimized. The rheology profiles of the different inks showed good shear thinning properties, demonstrating their suitability for screen-printing technology. The printability of the developed inks was excellent and in line with those of reference commercial carbon inks. Despite the lower electrical conductivity (400 S/m for the developed carbon ink compared to 1000 S/m for the commercial inks), which may be explained by their difference in composition (carbon content, density and carbon derived nature) compared to the commercial carbon, the developed ink functioned adequately as the counter electrode in all screen-printed electrochromic displays and even allowed for improved supercapacitors compared to those utilizing commercial carbon inks. In this sense, the supercapacitors incorporating the developed carbon ink in the current collector layer had an average capacitance = 97.4 mF/cm2 compared to the commercial carbon ink average capacitance = 61.6 mF/cm2). The ink development reported herein provides a step towards more sustainable printed electronics.

scholarly journals Stretchable and Washable Electroluminescent Display Screen-Printed on Textile

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1276 ◽  
Author(s):  
Daniel Janczak ◽  
Marcin Zych ◽  
Tomasz Raczyński ◽  
Łucja Dybowska-Sarapuk ◽  
Andrzej Pepłowski ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Mechanical Strength ◽  
Rheological Properties ◽  
Polymer Composites ◽  
Screen Printing ◽  
Printed Electronics ◽  
Wearable Electronics ◽  
Printing Technology ◽  
Wide Range ◽  
Screen Printing Technology

Stretchable polymer composites are a new group of materials with a wide range of application possibilities in wearable electronics. The purpose of this study was to fabricate stretchable electroluminescent (EL) structures using developed polymer compositions, based on multiple different nanomaterials: luminophore nanopowders, dielectric, carbon nanotubes, and conductive platelets. The multi-layered EL structures have been printed directly on textiles using screen printing technology. During research, the appropriate rheological properties of the developed composite pastes, and their suitability for printed electronics, have been confirmed. The structure that has been created from the developed materials has been tested in terms of its mechanical strength and resistance to washing or ironing.

Micromachining of an In-Fiber Extrinsic Fabry-Perot Interferometric (MEFPI) Sensor by Using a Femtosecond Laser

2007 ◽  
Vol 364-366 ◽  
pp. 1203-1206 ◽  
Author(s):  
Yun Jiang Rao ◽  
Ming Deng ◽  
Tao Zhu ◽  
Qing Tao Tang ◽  
Guang Hua Cheng
Keyword(s):  
Femtosecond Laser ◽  
Near Infrared ◽  
Fiber Optic ◽  
Low Cost ◽  
Good Reliability ◽  
Sensing Applications ◽  
Wide Range ◽  
Fabry Perot ◽  
Integration Degree ◽  
First Time

This paper reports a novel micro extrinsic fiber-optic F-P interferometric (MEFPI) sensor micromachined on a conventional optical fiber (Corning SMF-28) by using a near-infrared femtosecond laser, for the first time to the best of our knowledge. The strain and temperature characteristics of such a sensor were investigated and the experimental results show that the strain and temperature sensitivities are 0.006nm/με and -0.0017nm/°C, respectively. This type of MEFPI sensors has a number of advantages when compared with conventional EFPI sensors, such as easy fabrication, high integration degree, good reliability, low temperature cross-sensitivity, low cost, and capability for mass-production, offering great potential for a wide range of sensing applications.

scholarly journals Implementation of Radiating Elements for Radiofrequency Front-Ends by Screen-Printing Techniques for Internet of Things Applications

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3626 ◽  
Author(s):  
Imanol Picallo ◽  
Hicham Klaina ◽  
Peio Lopez-Iturri ◽  
Aitor Sánchez ◽  
Leire Méndez-Giménez ◽  
...  
Keyword(s):  
Internet Of Things ◽  
Screen Printing ◽  
Low Cost ◽  
Cost Effective ◽  
Wireless Transceivers ◽  
Test Environment ◽  
Angular Deflection ◽  
Wide Range ◽  
Flexible Antenna ◽  
Printing Techniques

The advent of the Internet of Things (IoT) has led to embedding wireless transceivers into a wide range of devices, in order to implement context-aware scenarios, in which a massive amount of transceivers is foreseen. In this framework, cost-effective electronic and Radio Frequency (RF) front-end integration is desirable, in order to enable straightforward inclusion of communication capabilities within objects and devices in general. In this work, flexible antenna prototypes, based on screen-printing techniques, with conductive inks on flexible low-cost plastic substrates is proposed. Different parameters such as substrate/ink characteristics are considered, as well as variations in fabrication process or substrate angular deflection in device performance. Simulation and measurement results are presented, as well as system validation results in a real test environment in wireless sensor network communications. The results show the feasibility of using screen-printing antenna elements on flexible low-cost substrates, which can be embedded in a wide array of IoT scenarios.

Safety assessment of biological raw materials in the system of medicines quality assurance

2020 ◽  
pp. 63-72
Author(s):  
Yu. Olefir ◽  
E. Sakanyan ◽  
I. Osipova ◽  
V. Dobrynin ◽  
M. Smirnova ◽  
...  
Keyword(s):  
Raw Materials ◽  
State Level ◽  
The State ◽  
Spongiform Encephalopathy ◽  
Safety Standards ◽  
Wide Range ◽  
The Russian Federation ◽  
Key Aspects ◽  
First Time ◽  
Medicines Quality

The entry of a wide range of biotechnological products into the pharmaceutical market calls for rein-forcement of the quality, efficacy and safety standards at the state level. The following general monographs have been elaborated for the first time to be included into the State Pharmacopoeia of the Russian Federation, XIV edition: "Viral safety" and "Reduction of the risk of transmitting animal spongiform encephalopathy via medicinal products". These general monographs were elaborated taking into account the requirements of foreign pharmacopoeias and the WHO recommendations. The present paper summarises the key aspects of the monographs.

Innovation in Byzantine Medicine

2020 ◽  
Author(s):  
Petros Bouras-Vallianatos
Keyword(s):  
Human Physiology ◽  
Medical Literature ◽  
Cultural Exchange ◽  
Significant Degree ◽  
Medieval Medicine ◽  
Medieval Latin ◽  
Main Thesis ◽  
Wide Range ◽  
Comprehensive Examination ◽  
First Time

Byzantine medicine is still a little-known and misrepresented field not only in the wider arena of debates on medieval medicine but also among Byzantinists. Byzantine medical literature is often viewed as ‘stagnant’ and mainly preserving ancient ideas; and our knowledge of it continues to be based to a great extent on the comments of earlier authorities, which are often repeated uncritically. This book presents the first comprehensive examination of the medical corpus of, arguably, the most important late Byzantine physician John Zacharias Aktouarios (c.1275–c.1330). The main thesis is that John’s medical works show an astonishing degree of openness to knowledge from outside Byzantium combined with a significant degree of originality, in particular, in the fields of uroscopy, pharmacology, and human physiology. The analysis of John’s edited (On Urines and On Psychic Pneuma) and unedited (Medical Epitome) works is supported for the first time by the consultation of a large number of manuscripts. The study is also informed by evidence from a wide range of medical sources, including previously unpublished ones, and texts from other genres, such as epistolography and merchants’ accounts. The contextualization of John’s works sheds new light on the development of Byzantine medical thought and practice, and enhances our understanding of the late Byzantine social and intellectual landscape. Finally, John’s medical observations are also examined in the light of examples from the medieval Latin and Islamic worlds, placing his medical theories in the wider Mediterranean milieu and highlighting the cultural exchange between Byzantium and its neighbours.

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