Droplet microfluidics on a planar surface

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorTorkkeli, Altti
dc.contributor.departmentDepartment of Electrical and Communications Engineeringen
dc.contributor.departmentSähkö- ja tietoliikennetekniikan osastofi
dc.date.accessioned2012-02-10T09:27:57Z
dc.date.available2012-02-10T09:27:57Z
dc.date.issued2003-10-03
dc.description.abstractThis work reports on the modelling of, and experiments on, a method in which liquid is transported as droplets on a planar hydrophobic surface with no moving parts, merely through electrostatic forces generated by the underlying electrodes. Two-directional transportation along a straight electrode path and across a junction, fusion of two droplets and methods for importing, exporting and filtering of water droplets were demonstrated, and can be used as basic functions of a lab-on-a-chip type microfluidic system. In this work, the electrostatic droplet actuation is for the first time demonstrated on super-hydrophobic surfaces. Such surfaces are composed of air-filled pores and exhibit a very low droplet sliding resistance due to reduced contact angle hysteresis and a high water contact angle (usually > 150°). This work shows that superhydrophobic surfaces can be used to reduce the minimum voltage and to increase the maximum speed under certain conditions, but there are some harmful side-effects. First of all, the electrostatic pressure can push water into the surface pores, which hinders actuation. The phenomenon can also be treated as a vertical electrowetting effect. Another drawback is that the use of superhydrophobic surfaces makes actuation more critical to the properties of the liquid. For example, actuation of biological buffer solutions was not successful. For these reasons, it is concluded that it is more beneficial to use a smooth surface with low hysteresis than a superhydrophobic surface in droplet actuation. Electrostatic droplet actuation is a potential method for manipulating liquid on a microscopic scale, but there is still work to do. This work contains a detailed examination of the droplet actuation mechanism, and trapping of charges in the solid-liquid interface is found to be the most severe problem that needs to be solved.en
dc.description.versionrevieweden
dc.format.extent194, [19]
dc.format.mimetypeapplication/pdf
dc.identifier.isbn951-38-6237-2
dc.identifier.issn1455-0849
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/2202
dc.identifier.urnurn:nbn:fi:tkk-001721
dc.language.isoenen
dc.publisherVTT Technical Research Centre of Finlanden
dc.publisherVTTfi
dc.relation.ispartofseriesVTT publicationsen
dc.relation.ispartofseries504en
dc.subject.keywordmicrofluidicsen
dc.subject.keywordlab-on-a-chipen
dc.subject.keywordelectrostatic droplet actuationen
dc.subject.keywordelectrowettingen
dc.subject.keywordsuperhydrophobic surfaceen
dc.subject.keywordMEMSen
dc.subject.otherElectrical engineeringen
dc.subject.otherPhysicsen
dc.titleDroplet microfluidics on a planar surfaceen
dc.typeG4 Monografiaväitöskirjafi
dc.type.dcmitypetexten
dc.type.ontasotVäitöskirja (monografia)fi
dc.type.ontasotDoctoral dissertation (monograph)en
local.aalto.digiauthask
local.aalto.digifolderAalto_63446
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