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Stroke Asymmetry of Tilted Superhydrophobic Ion Track Textures
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
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2010 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 9, 6790-6796 p.Article in journal (Refereed) Published
Abstract [en]

The stroke asymmetry of contact tingles of water drops on tilted hydrophobic textures is demonstrated, obtained by ion track etching followed by a hydrophobic treatment. Preliminary trends concerning the advancing and receding contact angles are established, each with and against stroke direction. In rough agreement with Cassie-Baxter theory, the cosines of these four contact angles depend linearly on the wetted area fraction. The etched tracks are randomly distributed on the surface of polycarbonate disks and inclined by 300 with respect to the surface, whereby the aspect ratio of individual etched cones is larger than 10. The morphology of the resulting surface is characterized by randomly shaped flat tops overhanging on one side and gradually falling off on the other side. The area fraction of the supporting tops can be calculated from the number of impinging ions per unit area and the cross section of the etched ion tracks. The top layer of the texture consists of flat, horizontal, irregularly shaped tops supporting water drops in the Cassie-Baxter state. With increasing etching time, the texture becomes increasingly defied. To fabricate the textures, we irradiated polyearbonate with 5 x 10(7) Br-80(7+) ions/cm(2) of 30 MeV total energy (having a range of about 20 mu m in polycarbonate) at a tilt angle of 30 with respect to the sample surface and etched the latent ion tracks selectively. The textured surface is made hydrophobic by carbondifluoride radicals (CF2) resulting from the decay of octafluorocyclobutane, C4F8, in a plasma reactor. The goal of the report is to show that the tilt orientation of a superhydrophobic surface leads to advancing and receding contact angles depending on the orientation with and against the stroke direction. In addition, a rotating movement is demonstrated qualitatively by floating a rotationally asymmetric disk on an ultrasonic bath, similarly treated after an irradiation with (1.2 +/- 0.4) x 10(7) Xe-129(274) MeV/cm- of 8.3 MeV/nucleon at an angle of 45 degrees, whereby the superhydrophobic side of the disk points downward to the water of the ultrasonic bath.

Place, publisher, year, edition, pages
2010. Vol. 26, no 9, 6790-6796 p.
National Category
Engineering and Technology Physical Sciences
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
URN: urn:nbn:se:uu:diva-111270DOI: 10.1021/la904137tISI: 000276969700105OAI: oai:DiVA.org:uu-111270DiVA: diva2:285390
Available from: 2010-01-11 Created: 2009-12-08 Last updated: 2017-12-12
In thesis
1. Ion Tracks for Micro- and Nanofabrication: From Single Channels to Superhydrophobic Surfaces
Open this publication in new window or tab >>Ion Tracks for Micro- and Nanofabrication: From Single Channels to Superhydrophobic Surfaces
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A method is described for preset-count irradiations between 1 and 100 ions singling-out individual ions from an ion beam with more than a billion ions arriving per second. The ion tracks are etched in a conductometric system with real-time evaluation of the acquired data. The etch process can be interrupted when reaching a preset channel diameter. Cylindrical channels are obtained by adding surfactants to the etch solution forming a self-assembled barrier between etching medium and polymer. Asymmetric etching of single ion tracks leads to pH sensitive conical pores with diode-like properties. Using etched channels as template, homogeneous and multilayer magnetic single-wires are electrodeposited. The magnetoresistivity of the wires is studied. Single-track applications comprise critical apertures (cylindric, conic, necked), asymmetric pores (pH sensitive, biospecific), Giant Magneto Resistance sensors, and spintronic devices.

On the basis of studies with individual ion tracks we tackled tilted multiporous systems such as ion beam lithography with a masked ion beam leading to micro-structures with inclined walls and anisotropic superhydrophobic ion track textures, analogous to biological shingle structures on butterfly wings. We demonstrated qualitatively, that the asymmetry of the texture translates into motion under ultrasonic agitation. This could lead to the development of rotary drives.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 63 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 700
Keyword
Ion track, single ion, real time, phase detection, conductometric cell, conductometry, electro replication, microtechnology, nanotechnology, surfactant, self organization, GMR, magnetic, sensor technology, hydrophobic, tilted texture.
National Category
Physical Sciences
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-111247 (URN)978-91-554-7683-0 (ISBN)
Public defence
2010-01-29, Polhemsaalen, Ångström Laboratorium, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
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Supervisors
Available from: 2010-01-07 Created: 2009-12-08 Last updated: 2010-01-15

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Spohr, ReimarForsberg, PontusKarlsson, MikaelHallén, AndersWesterberg, Lars

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