AC electrophoretic mobility of an optically trapped colloidal particle

Kohei Iki, Yasuyuki Kimura

Research output: Contribution to journalConference articlepeer-review


It is important to understand the dynamics of ions around charged colloidal particles from the fundamental and application viewpoints. In this study, we develop a new measurement method of AC electrophoretic mobility of a micrometer-sized single colloidal particle in a wide frequency range over four decades. Fast and precise detection of the displacement of the particle is achieved by laser-trapping of the particle and using laser interferometry. The complex mobility of a silica particle of diameter of 1 μm dispersed in water is measured from 10 Hz to 10 kHz. The obtained apparent spectrum is found to contain the influence of laser trapping at lower frequencies and the dynamics of electro-osmotic flow induced by the charged cell surfaces. We succeed to observe the dynamics of the electrically induced bulk flow in a 100-μm-thick cell threedimensionally for the first time.

Original languageEnglish
Article numberOMC-5-02
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2019
EventOptical Manipulation and Structured Materials Conference 2019 - Yokohama, Japan
Duration: Apr 22 2019Apr 26 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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