Project

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Direct force measurements with combined total internal reflection and atomic force microscopy

English title Direct force measurements with combined total internal reflection and atomic force microscopy
Applicant Borkovec Michal
Number 150631
Funding scheme R'EQUIP
Research institution Département de Chimie Minérale et Analytique Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Physical Chemistry
Start/End 01.12.2013 - 31.05.2015
Approved amount 198'000.00
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All Disciplines (2)

Discipline
Physical Chemistry
Material Sciences

Keywords (5)

total internal reflection microscopy ; direct force measurement; atomic force microscopy; colloidal particles; surface forces

Lay Summary (German)

Lead
Kräfte zwischen kolloidalen Partikeln werden in diesem Projekt gemessen.
Lay summary
In diesem Projekt wird ein Mikroskop konstruiert, welches eine genaue Messung der Kräfte zwischen kolloidalen Partikeln erlaubt. Solche Kräfte sind zum Beispiel bei der Abwasser-Reinigung von Bedeutung. Abwasser enthält grössere Mengen an schwebenden Partikeln, und diese können abgetrennt werden, indem anziehende Kräfte zwischen den Partikeln durch den Zusatz geeigneter Flockungs-Mittel induziert werden.

Das geplante Mikroskop wird in der Lage sein, solche Kräfte mit Teilchen von Durchmesser kleiner als ein Mikrometer zu erfassen. Solche Messungen werden bewerkstelligt, indem ein solches Teilchen an einem flexiblen Träger fixiert wird. Wenn das Teilchen in die Nähe von einem Substrat gebracht wird, verbiegt sich der Träger, und auf diese Weise kann die Kraft zwischen dem Teilchen und dem Substrat gemessen werden. Das neue System wird auch in der Lage sein, den Abstand zwischen den Oberflächen mit einer Genauigkeit von besser als einem Nanometer zu bestimmen.

Dieses Gerät wird in laufenden Forschungs-Projekten eingesetzt, um die Mechanismen solcher Kräfte besser zu verstehen. Solches Verständnis kann beispielsweise dafür eingesetzt werden, um bessere Flockungsmittel zu entwickeln. In der Zukunft wird man auf diese Weise stark verschmutzte Abwasser effizienter reinigen können.
Direct link to Lay Summary Last update: 14.11.2013

Responsible applicant and co-applicants

Collaboration

Group / person Country
Types of collaboration
Alberto Morpurgo, Univ. Geneva Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Paul Dyson, EPFL Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Nicolas Spencer, ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Andreas Kilbinger, Univ. Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Christophe Labbez, Univ. Bourgogne France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Ger Koper, TU Delft Netherlands (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dieter Schlüter, ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Sven Behrens, Georgia Tech. United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Christophe Weder, Univ. Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Associated projects

Number Title Start Funding scheme
136191 Designing Interactions across Interfaces in Ionic Liquids 01.01.2012 Sinergia
140327 Tuning Interactions between Dissimilar Surfaces by Polyelectrolytes 01.06.2012 Project funding
159874 Polyelectrolytes near like-charged substrates in the presence of multivalent ions 01.06.2015 Project funding

Abstract

The aim of this project is to realize an atomic force microscope (AFM) combined with a total internal reflection microscope (TIRM). This instrument will be optimized for direct force measurements involving colloidal particles and planar substrates, and enable us to make independent measurement of the forces and surface separations with resolutions better than pN and nm, respectively. The colloidal probe technique will be used to measure forces by probing the deflection of the AFM cantilever to which a particle will be attached. The surface separation will be obtained directly through TIRM by means of the luminosity of the particle, which will be detected by an optical microscope. Independent force and distance measurements are essential for the study of solvation forces, and interactions involving soft or deformable substrates, such as adsorbed polymer layers, bubbles, or vesicles. TIRM will be equally used to investigate weak interaction potentials by probing the distance distribution induced by thermal fluctuations. With this technique one may achieve a superior force resolution than with the AFM. The instrument will be principally used in running research projects, whereby two main questions will be pursued. First, we will study interactions induced by dissolved polyelectrolytes, and thereby measure forces-distance profiles involving soft adsorbed layers whereby the actual surface separation will be recorded. Structural forces that occur at higher concentrations will be probed as well. Second, solvation forces induced by ionic liquids will be investigated. An independent distance determination is essential in this case as well, since one would like to establish whether all solvation layers can be displaced under load. Several other research groups at the University of Geneva have expressed interest to use this instrument as well.
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