Edinburgh Research Explorer

Linear and nonlinear microrheology of dense colloidal suspensions

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Related Edinburgh Organisations

Original languageEnglish
Title of host publicationOptical Trapping and Optical Micromanipulation III
EditorsK Dholakia, GC Spalding
Place of PublicationBELLINGHAM
Number of pages10
ISBN (Print)0-8194-6405-8
Publication statusPublished - 2006
EventConference on Optical Trapping and Optical Micromanipulation III - San Diego
Duration: 13 Aug 200617 Aug 2006


ConferenceConference on Optical Trapping and Optical Micromanipulation III
CitySan Diego


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


Conference on Optical Trapping and Optical Micromanipulation III


San Diego

Event: Conference

ID: 1488454