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Linear and nonlinear microrheology of dense colloidal suspensions

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Original languageEnglish
Title of host publicationOptical Trapping and Optical Micromanipulation III
EditorsK Dholakia, GC Spalding
Place of PublicationBELLINGHAM
PublisherSPIE
PagesU441-U450
Number of pages10
ISBN (Print)0-8194-6405-8
DOIs
StatePublished - 2006
EventConference on Optical Trapping and Optical Micromanipulation III - San Diego

Conference

ConferenceConference on Optical Trapping and Optical Micromanipulation III
CitySan Diego
Period13/08/0617/08/06

Abstract

The length and time scales accessible to optical tweezers make them an ideal tool for the examination of colloidal systems. Embedded high-refractive-index tracer particles in an index-matched hard sphere suspension provide 'handles' within the system to investigate the mechanical behaviour. Passive observations of the motion of a single probe particle give information about the linear response behaviour of the system, which can be linked to the macroscopic frequrency-dependent viscous and elastic moduli of the suspension. Separate 'dragging' experiments allow observation of a sample's nonlinear response to an applied stress on a particle-by particle basis. Optical force measurements have given new data about the dynamics of phase transitions and particle interactions; an example in this study is the transition from liquid-like to solid-like behaviour, and the emergence of a yield stress and other effects attributable to nearest-neighbour caging effects. The forces needed to break such cages and the frequency of these cage breakign events are investigated in detail for systems close to the glass transition.

    Research areas

  • laser trapping, optical tweezers, trapping potential, colloidal glasses, microrheology, DIELECTRIC PARTICLES, GLASS-TRANSITION, MODEL SYSTEM, HARD-SPHERE, FLOW

Event

Conference on Optical Trapping and Optical Micromanipulation III

13/08/0617/08/06

San Diego

Event: Conference

ID: 1488454