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KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).ORCID iD: 0000-0001-6443-878X
KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).ORCID iD: 0000-0001-9552-4234
KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).ORCID iD: 0000-0001-8248-6670
2008 (English)In: 21st IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2008), IEEE conference proceedings, 2008, 595-598 p.Conference paper (Refereed)
Abstract [en]

We introduce a novel approach for greatly improved transport and trapping of airborne sample to a microfluidic analysis system by integrating an electrohydrodynamic (EHD) air pump with a microfluidic air-liquid interface. In our system, a negative corona discharge partially ionizes the air around a sharp electrode tip while the electrostatic field accelerates airborne particles towards an electrically grounded liquid surface, where they absorb. The air-liquid interface is fixated at the microscale pores of a perforated silicon diaphragm, each pore functioning as a static Laplace valve. Our system was experimentally tested using airborne smoke particles of ammonium chloride and aqueous salt solution as the liquid. We measured that EHD enhanced transport of the particles from the air into the liquid is enhanced over 130 times compared to passive trapping.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2008. 595-598 p.
, Proceedings: IEEE micro electro mechanical systems, ISSN 1084-6999
Keyword [en]
Ammonium compounds; Composite micromechanics; Electric corona; Electrohydrodynamics; Fluid dynamics; Fluid mechanics; Hydrodynamics; Liquids; Mechanical engineering; Mechanics; Mechatronics; MEMS; Microelectromechanical devices; Nanofluidics; Nonmetals; Reactive ion etching; Silicon
National Category
Control Engineering
URN: urn:nbn:se:kth:diva-14190DOI: 10.1109/MEMSYS.2008.4443726ISI: 000253356900149ScopusID: 2-s2.0-50149095599ISBN: 978-1-4244-1792-6OAI: diva2:331623
21st IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2008), Tucson, AZ,13-17 Jan, 2008

QC 20100723

Available from: 2010-07-23 Created: 2010-07-23 Last updated: 2015-06-03Bibliographically approved
In thesis
1. MEMS Interfaces for Bioanalysis Systems
Open this publication in new window or tab >>MEMS Interfaces for Bioanalysis Systems
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis deals with various aspects of using open microfluidic interfaces. Three specific areas of application are studied.

The first is air-to-liquid interfacing in biosensors with possibilities for component inte­gration. A micromachined interface for airborne sample-to-liquid and droplet-to-liquid adsorption is discussed. It enables a robust sheet liquid flow serving as adsorption site. The inter­face properties are presented. Along with the interface, a novel method and system for rapid detection of dust and vapour-based narcotics and explosives traces is introduced. The QCM sensor detection principle with antibody immunoassay is described. Having shown the working principles of molecular adsorption to liquid surface and molecular detection with QCM technology, an integrated device is introduced. Diffusion as an effective transport mechanism in this microfluidic device is discussed. By holding the two components (inter­face and QCM) together with a double-sided adhesive, anisotropically vertically conductive tape, we achieve three functions, namely fixation, electrical connection and liquid sealing. Finally, enhanced electrostatic trapping of small particles to the liquid interface is demon­strated.

The second area concerns open microfluidics for the integration of capillary electropho­resis and mass spectroscopy. A technique for hyphenation between CE and MALDI-MS is presented. Two closed fused-silica capillaries were connected via a silicon chip comprising an open microcanal. The influence of the capillary-to-microcanal connection is discussed, as well as a simple technique to control evaporation from the open microcanal.

The third area concerns microfluidics enabling studies of single cells in asymmetric en­vironments. Using extracellular matrix or synthetic gel-embedding cells in an assay chamber, cells thrive and proliferate. This makes it possible to carry out medium to long term cultiva­tion of cells in a more physiological, controlled 3D environment than in traditional 2D cul­tures. The gels are discussed in terms of handling as well as their properties. A gel and micro­fluidic device for three dimensional cell culture with microgradient environments is pre­sented. Finally, a method for studying cilia-forming cells in asymmetric microfluidic environments is presented. Bending the primary cilium with a fluid flow will give rise to a response, but sensitivity to flow direction has only been sparsely studied. Design considerations are presented and discussed.

Abstract [sv]

Den här avhandlingen diskuterar olika aspekter av den öppna gränsytan hos styckevis öppna mikrofluidiksystem. Tre specifika användningsområden har studerats.

Det första är gränsytan mellan luft och vätska i en biosensor och de användningsområ­den som finns här. Ett mikrofabricerat interface för adsorption av luftburna substanser samt dropp-absorption diskuteras. Här används en rörlig vätskeyta som adsorbtionsyta och dess egenskaper presenteras. En ny metod för sprängämnes- och narkotikadetektering med interfa­cet introduceras. QCM-tekniken i kombination med antikroppskemi beskrivs. En integrerad lösning med dessa tekniker introduceras där diffusion utgör en effektiv transportmekanism. Med en dubbelsidig ledande tejp hålls komponenterna ihop, tätas och förses med ström. Slut­ligen presenteras elektrostatisk infångning av partiklar där den ena elektroden utgörs av väts­keytan.

Det andra området berör ett öppet mikrofluidiksystem för integrering av kapillärelek­trofores och masspektrometri. Teknik för att koppla ihop CE och MALDI-MS presente­ras. Två glaskapillärer har kopplats ihop med ett kiselchip med en öppen mikrokanal. Kopp­lingen mellan kapillären och chippet diskuteras liksom en enkel teknik för att kontrol­lera avdunstningen från den öppna mikrokanalen.

Det tredje området diskuterar hur mikrofluidik möjliggör studier av cellulära reaktioner i asymmetriska miljöer. Med inbäddning av celler i extracellulär matris eller syntetisk gel fås fysiologiskt relevant lokal miljö för celltillväxt och celldelning. Detta möjliggör studier av cellutveckling och cellreaktioner under lång tid i faktisk 3D-miljö till skillnad från den nuva­rande etablerade 2D-miljön. Gelerna diskuteras ur en hanteringssynpunkt liksom utifrån sina egenskaper. Ett system för cellodling i 3D med gradi­entmiljö presenteras och diskuteras. Slutligen presenteras ett system för studier av ciliefor­mande cellers respons där asymmetriska flöden ger upphov till böjning av cilier. Olika de­signaspekter diskuteras.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. xii, 56 p.
Trita-EE, ISSN 1653-5146 ; 2008:002
microfluidic interfacing, microfluidics, µTAS, sample transfer, biosensor, electronic nose, surface tension, quartz crystal microbalance, QCM, narcotics detection
National Category
Control Engineering
urn:nbn:se:kth:diva-4609 (URN)978-91-7178-846-7 (ISBN)
Public defence
2008-02-08, Sal M3, KTH, Brinellvägen 64, Stockholm, 10:00
QC 20100927Available from: 2008-01-18 Created: 2008-01-18 Last updated: 2010-09-27Bibliographically approved

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