Introduction
Drop-on-demand inkjet-printing (DOD IJP) is a versatile digital printing technique that allows for direct patterning of a wide range of functional materials such as polymers, polymer composites, as well as different types of nanomaterials. In this technique, pico-liter droplets are generated and precisely positioned on substrates. The possibility of positioning a small volume of material precisely on the substrate as well as contactless patterning has made DOD IJP an interesting technique in the fields such as fabricating optical components (e.g. microlens arrays), electronic devices (e.g. thin film transistors), sensors (e.g. chemical sensors), as well as tissue engineering (i.e. cell patterning).
Working principle and some examples
In LMIS1 we are using a piezo-actuated drop-on-demand inkjet printer developed by Microfab Technology. In this printer, the dispenser consists of an annular piezoelectric element, which is attached to a capillary glass tube. When a pulsed voltage waveform is applied to the piezo-element a sudden change of volume occurs in the capillary glass that generates acoustic pressure waves inside the capillary tube and consequently expels a small volume of liquid from the orifice. For droplets to be generated physical properties of the ink e.g. viscosity and surface tension, have to be carefully tuned and printing parameters (e.g. applied waveform) have to be optimized. The image below shows how a droplet is generated from an ink containing a polymer, using a piezo-actuated nozzle.
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Figure 1: Generation of pico-liter droplets using a piezo-actuated DOD IJP. |
Liquid encapsulation in microdevices
Current technology allows us to create amazingly small physical devices. However, the precise deposition and protection of pL volumes of liquid need to be improved as a consequence. The time-window to encapsulate picolitres of water-based ink is less than a minute before significant evaporation takes place. The loss of liquid can disturb the concentrations contained within the ink for correct function. We use DOD IJP to print our desired ink into defined open vessels. We immediately print an oil-based UV-curable encapsulating layer. Thereafter upon UV curing, crosslinking occurs and forms a barrier to protect the underlying ink from evaporation and external influence.
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Figure 2: PDMS samples with wells of 300µm internal lengths are filled with a water-based ink. Before complete evaporation takes place, an immiscible ink is deposited on top to encapsulate the ink underneath before UV treatment. |
Printing polymer composites for gas sensing applications
One of the ongoing research activities in our lab regarding IJP is to formulate inks containing polymer nanocomposites (PNCs) for applications in chemical gas sensing using sensor arrays (i.e. electronic nose devices). Since IJP enables us to directly deposit functional materials on a substrate it is a suitable technique for fabricating sensor arrays where each sensor consists of a different material. For this aim we formulate inks containing PNCs, study their printability and investigate their response to different volatile organic compounds (e.g. acetone, and ethanol).
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Figure 3: The image (a) shows an exploded view of the sensor device used for characterization of inkjet-printed polymer composites. The image (b) demonstrate working principle of chemiresistive sensors based on polymer composites. The image (c) shows a representative result indicating the response of a printed polystyrene/carbon black composite to acetone. The inset of the image shows a picture of the printed sensor. |
Keywords: inkjet, ink-jet, microlense, microdrop
Journal papers
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Near-Room-Temperature Detection of Aromatic Compounds with Inkjet-Printed Plasticized Polymer Composites
Acs Sensors. 2024-03-13. Vol. 9, num. 3, p. 1382-1390. DOI : 10.1021/acssensors.3c02406.Inkjet‐Printed Composites for Room‐Temperature VOC Sensing: From Ink Formulation to Sensor Characterization
Advanced Materials Technologies. 2020-12-06. p. 1-11, 2000929. DOI : 10.1002/admt.202000929.Microdrop generation and deposition of ionic liquids
Journal Of Materials Research. 2014. Vol. 29, num. 17, p. 2100-2107. DOI : 10.1557/jmr.2014.162.Inkjet printed superparamagnetic polymer composite hemispheres with programmed magnetic anisotropy
Nanoscale. 2014. Vol. 6, p. 10495-10499. DOI : 10.1039/C3NR06442E.PDMS-based, magnetically actuated variable optical attenuators obtained by soft lithography and inkjet printing technologies
Sensors And Actuators A-Physical. 2014. Vol. 215, p. 30-35. DOI : 10.1016/j.sna.2014.01.021.Inkjet Printing of High Aspect Ratio Superparamagnetic SU-8 Microstructures with Preferential Magnetic Directions
Micromachines. 2014. Vol. 5, p. 583-593. DOI : 10.3390/mi5030583.Fabrication of HepG2 Cell Laden Collagen Microspheres using Inkjet Printing
Journal of the Korean Society for Precision Engineering. 2014. Vol. 31, num. 8, p. 743-747. DOI : 10.7736/KSPE.2014.31.8.743.Inkjet-printed SU-8 Hemispherical Microcapsules and Silicon chip Embedding
IET Micro & Nano Letters. 2013. Vol. 8, num. 10, p. 633-636. DOI : 10.1049/mnl.2013.0241.Simple and easily controllable parabolic-shaped microlenses printed on polymeric mesas
Journal Of Materials Chemistry C. 2013. Vol. 1, num. 11, p. 2152-2157. DOI : 10.1039/c3tc00632h.Heterogeneous material micro-transfer by ink-jet print assisted mould filling
Microelectronic Engineering. 2012. Vol. 98, p. 619-622. DOI : 10.1016/j.mee.2012.04.025.Fabrication of epoxy spherical microstructures by controlled drop-on-demand inkjet printing
Journal of Micromechanics and Microengineering. 2012. Vol. 22, num. 7, p. 074012. DOI : 10.1088/0960-1317/22/7/074012.Nanocomposites based on highly luminescent nanocrystals and semiconducting conjugated polymer for inkjet printing
Nanotechnology. 2012. Vol. 23, num. 7, p. 075701. DOI : 10.1088/0957-4484/23/7/075701.Directly fabricated multi-scale microlens arrays on a hydrophobic flat surface by a simple ink-jet printing technique
Journal of Materials Chemistry. 2012. Vol. 22, num. 7, p. 3053-3058. DOI : 10.1039/c2jm15576a.Microdrop Printing of Hydrogel Bioinks into 3D Tissue-Like Geometries
Advanced Materials. 2012. Vol. 24, num. 3, p. 391-396. DOI : 10.1002/adma.201102800.Microlenses with defined contour shapes
Optics Express. 2011. Vol. 19, num. 19, p. 18665. DOI : 10.1364/OE.19.018665.Hybrid polymer microlens arrays with high numerical apertures fabricated using simple ink-jet printing technique
Optical Materials Express. 2011. Vol. 1, num. 2, p. 259-269. DOI : 10.1364/OME.1.000259.Drop-on-demand inkjet printing of highly luminescent CdS and CdSe@ZnS nanocrystal based nanocomposites
Microelectronic Engineering. 2009. Vol. 86, p. 1124-1126. DOI : 10.1016/j.mee.2008.11.028.Inkjet-Printed Multicolor Arrays of Highly Luminescent Nanocrystal-Based Nanocomposites
Small. 2009. Vol. 5, p. 1051-1057. DOI : 10.1002/smll.200801315.Drop-On-Demand Inkjet Printing of SU-8 Polymer
Micro and Nanosystems. 2009. Vol. 1, num. 1, p. 63-67. DOI : 10.2174/1876402910901010063.Conference papers
Please note that the publication lists from Infoscience integrated into the EPFL website, lab or people pages are frozen following the launch of the new version of platform. The owners of these pages are invited to recreate their publication list from Infoscience. For any assistance, please consult the Infoscience help or contact support.