Printmaking | EPFL Graph Search

Printmaking is the process of creating artworks by printing, normally on paper, but also on fabric, wood, metal, and other surfaces. "Traditional printmaking" normally covers only the process of creating prints using a hand processed technique, rather than a photographic reproduction of a visual artwork which would be printed using an electronic machine (a printer); however, there is some cross-over between traditional and digital printmaking, including risograph. Prints are created by transferring ink from a matrix to a sheet of paper or other material, by a variety of techniques. Common types of matrices include: metal plates for engraving, etching and related intaglio printing techniques; stone, aluminum, or polymer for lithography; blocks of wood for woodcuts and wood engravings; and linoleum for linocuts. Screens made of silk or synthetic fabrics are used for the screen printing process. Other types of matrix substrates and related processes are discussed below. Except in t

Fully 3D Printed Mechanical Pressure Sensors: A Comparison of Sensing Mechanisms

Julien Gaëtan Berger, Danick Briand, Rubaiyet Iftekharul Haque, Ryan Mitchell van Dommelen

Recent advances in 3D printing techniques are allowing for new ways to manufacture sensors with materials and geometries previously not exploited. In this work we present a fabrication approach for fully 3D printed soft mechanical pressure sensors, as well as their characterisation. These sensors were created out of soft materials only using the Direct Ink Writing (DIW) printing technique. The applicability of both piezoresistive and capacitive transducing mechanisms were evaluated for the sensing of normal pressures. The produced sensors were tested by means of automated mechanical tests and compared based on their performance. In this way, we determined and analysed both their static and dynamic behaviours.

IEEE2020

Properties and Printability of Inkjet and Screen-Printed Silver Patterns for RFID Antennas

Danick Briand, Nico de Rooij, Francisco Molina Lopez, Jinyu Jason Ruan

We report the modeling, and geometrical and electrical characterization, of inkjet and screen-printed patterns on different polymeric substrates for use as antennas in radio-frequency identification (RFID) applications. We compared the physical and electrical characteristics of two silver nanoparticle-based commercial inkjet-printable inks and one screen-printable silver paste, when deposited on polyimide (PI), polyethylene terephthalate (PET), and polyetherimide (PEI) substrates. First, the thickness of the inkjet-printed patterns was predicted by use of an analytical model based on printing conditions and ink composition. The predicted thickness was confirmed experimentally, and geometrical characterization of the lines was completed by measuring the root-mean-square roughness of the patterns. Second, direct-current electrical characterization was performed to identify the printing conditions yielding the lowest resistivity and sheet resistance. The minimum resistivity for the inkjet-printing method was 8.6 +/- A 0.8 mu I (c) cm, obtained by printing four stacked layers of one of the commercial inks on PEI, whereas minimum resistivity of 44 +/- A 7 mu I (c) cm and 39 +/- A 4 mu I (c) cm were obtained for a single layer of screen-printed ink on polyimide (PI) with 140 threads/cm mesh and 90 threads/cm mesh, respectively. In every case, these minimum values of resistivity were obtained for the largest tested thickness. Coplanar waveguide transmission lines were then designed and characterized to analyze the radio-frequency (RF) performance of the printed patterns; minimum transmission losses of 0.0022 +/- A 0.0012 dB/mm and 0.0016 +/- A 0.0012 dB/mm measured at 13.56 MHz, in the high-frequency (HF) band, were achieved by inkjet printing on PEI and screen printing on PI, respectively. At 868 MHz, in the ultra-high-frequency band, the minimum values of transmission loss were 0.0130 +/- A 0.0014 dB/mm for inkjet printing on PEI and 0.0100 +/- A 0.0014 dB/mm for screen printing on PI. Although the resistivity achieved is lower for inkjet printing than for screen printing, RF losses for inkjetted patterns were larger than for screen-printed patterns, because thicker layers were obtained by screen printing. Finally, several coil inductors for the HF band were also fabricated by use of both printing techniques, and were used as antennas for semi-passive smart RFID tags on plastic foil capable of measuring temperature and humidity.

Springer Verlag2014

Implementation of Functional Microfluidic Dispensing Tools Enabling Enhanced Control in Extrusion Bioprinting

Ludovic Serex

Inspired from additive manufacturing's success, the structuring of biocompatible materials through bioprinting has become a growing field of research in the past fifteen years. It opened the door to a plethora of applications ranging from the fabrication of tissue models for research to regenerative medicine. This field of research has mainly been tackled from a biological view point to study the culture of cells ''ex-vivo'' as well as through a materials science lens as to synthesize extracellular matrices. Per contra, the tools currently used for bioprinting do not allow advanced manipulations that are needed to reproduce the complex structures found in tissues. This sets strict limitations on what can be achieved by bioprinting. This thesis proposes an engineering perspective on bioprinting by providing new tools which improve the level of control over deposited biomaterials through extrusion bioprinting. The advancements in microfluidic technology are leveraged to micromanufacture extrusion tools serving as printing heads for bioprinters. Successful implementation of a microfluidic mixer combined with a heating element and temperature sensor in an extrusion tool, enabled the printing of cryogels. These macroporous materials display remarkable properties, such as high pore interconnection, large surface to volume ratio and high mechanical stability. A collagen coating that is covalently bonded to the cryogel has been developed to enable the culture of adherent cells within the printed scaffold. Using the heating element, the pores' size of the printed cryogel can be controlled during printing allowing the selection of the position of the seeded cells. A cell concentrator capable of working as a printing head was implemented. The ability to concentrate cells just before printing presents remarkable advantages such as reduced risk of cell lysis in tubings and reduced cell losses in dead volumes of bioprinters. As evidence of the beneficial effects of printing at a high cell concentration were found, such tools provide the opportunity to work at high cellular concentrations without the complications usually associated with it. The implementation of a microfluidic mixer downstream of the cell concentrator enables the addition of extracellular matrix, providing a complete platform for tissue printing at high cell concentration. Using this tool, fibroblasts were printed at high concentration in a collagen matrix. Moreover, using the concentrator, primary uroepithelial cells were printed in a basement membrane extract. The control over the cellular concentration allowed for the optimization of the amount of printed cells which has been demonstrated to have a major impact on bladder organoid formation. Finally, as many extracellular matrices take several minutes to crosslink, multi-layer 3D printing of these materials can be challenging. Hence solutions for the printing of liquid materials are explored through the creation of a composite biomaterial, co-printing of rigid support materials and liquid materials using a dedicated extrusion head and the printing of liquid materials within a supporting gel. These printing techniques allowed to cope with the long curing time of certain bioinks and to shape them in 3D. The tools developed in this work set the ground for the development of a new generation of bioprinters providing more freedom for the design and printing of functional tissues through enhanced control over the printed materials.

EPFL2019