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A Basic Investigation of Capillary Nanospraying and On-Demand Printing by Electrowetting for the Maskless Deposition of Colloids

English title A Basic Investigation of Capillary Nanospraying and On-Demand Printing by Electrowetting for the Maskless Deposition of Colloids
Applicant Poulikakos Dimos
Number 125041
Funding scheme Project funding (Div. I-III)
Research institution Institut für Energietechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Mechanical Engineering
Start/End 01.09.2009 - 31.08.2012
Approved amount 382'949.00
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All Disciplines (2)

Discipline
Mechanical Engineering
Fluid Dynamics

Keywords (5)

inkjet; microfluidics; nanofabrication; electrowetting; colloids

Lay Summary (English)

Lead
Lay summary
This project is a fundamental investigation of a novel, capillarity-related, maskless method for the non-contact deposition of nanoparticle colloids leading to the generation of 2D and 3D functional submicron structures at room conditions. State of the art non-contact direct writing is realized by ink-jet printers, but limited to feature sizes of several micrometers. A further downsizing of this technology has proven to be difficult and prohibitingly high pressure is required to mechanically eject droplets by piezoelectric or thermal actuation.Using our novel electro-hydrodynamic approach, submicron printing out of capillary openings is feasible and has already been demonstrated to yield functional micro and nanostructures as much as two orders of magnitude slammer that the several micron features printed by inkjet technologies. In contrast to existing technologies, this novel mechanism allows for the deposition of not only 2D but also of 3D structures (nanowires) well into the submicron range. Since the physical mechanisms of the colloidal microdroplet generation out of capillary openings and its control are not fully understood, a detailed investigation of the physical processes involved includes aspects of submicron scale fluid dynamics, electrohydrodynamics of colloids, wetting phenomena, and rapid vaporization processes.In addition to the theoretical approach, a detailed experimental study will cover a wide parametric domain of wall materials, cavity geometries, colloid properties and electrostatic field aspects, thus creating a science base for this technology. Reducing the feature size by printing out of nozzle openings as small as O(100) nm is part of the envisioned results as well as the investigation of the thermal processing of exemplary functional structures obtained with the methods, in particular for metallic and semiconducting nanoparticle materials. Printing on curved surfaces as a special feature of the novel deposition process will be an additional subject of investigation.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Direct printing of nanostructures by electrostatic autofocussing of ink nanodroplets
Galliker Patrick, Schneider Julian, Eghlidi Hadi, Kress Stephan, Sandoghdar Vahid, Poulikakos Dimos (2012), Direct printing of nanostructures by electrostatic autofocussing of ink nanodroplets, in NATURE COMMUNICATIONS, 3, 1-9.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
MRS spring meeting 09.04.2012 San Francisco, USA


Communication with the public

Communication Title Media Place Year
New media (web, blogs, podcasts, news feeds etc.) ETH-Forscher entwickeln Nano-Superdrucker 20min Online German-speaking Switzerland 06.06.2012
New media (web, blogs, podcasts, news feeds etc.) Neues Druckverfahren für Nanostrukturen ETH Life German-speaking Switzerland 13.06.2012
New media (web, blogs, podcasts, news feeds etc.) Nano drop by drop President's Selection German-speaking Switzerland 01.11.2011

Awards

Title Year
Venture 2012 Business Idea 2012
Venture Kick 2012

Associated projects

Number Title Start Funding scheme
107450 Fundamental thermofluidic and interfacial phenomena in "fountain pen" based micro/nano-writing and curing of nanopartilce inks 01.05.2005 Project funding (Div. I-III)
146180 Facile nanostructuring by direct printing: Fundamentals and applications in light-nanostructure interactions 01.04.2013 Project funding (Div. I-III)
67738 Explosive Vaporization Phenomena in Microenclosures 01.01.2003 Project funding (Div. I-III)

Abstract

We propose herein the fundamental investigation of two novel, both capillarity-related, maskless methods for the deposition of nanoparticle colloids leading to the generation of 2D and 3D functional submicron structures: (a) electrowetting-driven demand printing (b) capillary nanospray deposition. These methods contain interesting and unexplored physics and can be significant advancements over existing technologies. They enable deposition of structures well in the submicron range, which is not amenable by the current state of the art inkjet technologies. Furthermore, they allow deposition of not only 2D but also of 3D structures in a continuous (capillary nanospraying) or discrete- on demand (capillary electrowetting) manner. The deposited nanoparticle structures can already be largely depleted of solvent, facilitating further processing (e.g. thermal), and they can be successfully placed on strongly curved substrates, which are problematic with mask-based technologies. A number of open basic scientific questions related to these novel deposition concepts deserve careful investigation and will constitute the main goals of this proposal. To this end, the main research tasks of the proposed work are:i.Investigation of the physical mechanisms of colloidal microdroplet generation in electrowetting-driven submicron demand-printing. The colloid will be confined in an open-ended capillary cavity and will exhibit a wetting behavior with respect to the walls. Electrowetting behavior of the meniscus at the capillary opening is unlikely to generate (eject) colloidal microdroplets. The latter can be realized by the presence of an additional meniscus in the capillary cavity and a strongly non-uniform cross section of the same. The wetting behavior of the colloid with respect to the wall material, particularly the dynamics at the contact line region, is expected to play an important role. Once the exact physical mechanism is understood, the study will cover a wide parametric domain of wall materials, cavity geometries and sizes, colloid properties and voltage ranges, thus creating a science base for this technology.ii.Experimental investigation of capillary nanospraying as a mechanism of the generation of 2D and 3D nanoparticle-based structures. In this case, it has been observed in our preliminary studies that colloids inserted through the action of capillarity in certain micro- or nanoscale channels, can exit these channels spontaneously in the form of a controllable nanospray that can lead to the generation of the abovementioned structures. The mechanism of the spray generation and its control are not entirely understood and will constitute the focus of this part of the proposed research. Understanding the related mechanisms will involve vaporization processes from menisci containing nanoparticles in openings as small as O(100) nm. The thermal manipulation of the surface tension of a colloidal meniscus in a capillary channel will also be investigated as a means of liquid propagation in the channel. Once the exact physical mechanisms are understood relevant parametric studies as in point i) above will be carried out to generate a knowledge base for this technology. iii.Investigation of the thermal processing (for example laser heat input for further sintering) of exemplary structures obtained with the methods in both parts i) and ii) above, in particular for metallic and semiconducting nanoparticle materials.In summary, the results of the research proposed herein will piece together a fundamental knowledge base for the maskless deposition of nano- and microscale structures by two novel, capillarity based, mechanisms showing promise for 2D and 3D structures on flat or curved substrates. In addition to its merit from the fundamental standpoint, this research is a necessary step toward the possible future development of novel technologies based on the proposed concept.
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