Flow sandwich-type immunoassay in microfluidic devices based on negative dielectrophoresis

Tomoyuki Yasukawa, Masato Suzuki, Takashi Sekiya, Hitoshi Shiku, Tomokazu Matsue

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)


Microparticles have been manipulated in a microfluidic channel by means of negative dielectrophoresis (n-DEP), and the approach applied to a heterogeneous immunoassay system. A microfluidic device, with three-dimensional (3-D) microelectrodes fabricated on two substrates, was used to manipulate particle flow in the channel and to capture the particles in the caged area that was enclosed by the collector electrodes. Polystyrene microparticles (6 μm diameters) modified with anti-mouse immunoglobulin G (IgG) were manipulated and captured in the caged area when surrounded by intense n-DEP electric fields. Specifically, particles were trapped when AC voltages with amplitudes of 6-15 Vpeak and frequencies over 500 kHz were applied to the two facing microelectrodes. A heterogeneous sandwich immunoassay was achieved by successively injecting a sample solution containing mouse antigen (IgG), and a solution containing a secondary antibody with a signal source (FITC-labeled anti-mouse IgG antibody), into the channel. The fluorescence intensity from captured particles in the caged area increased with increasing concentrations (10 ng/ml to 10 μg/ml) of mouse IgG. The described system enables mouse IgG to be assayed in 40 min. Thus, the automatic separation of free fractions from desired analytes and labeled antibodies can be achieved using a microfluidic device based on n-DEP.

Original languageEnglish
Pages (from-to)2730-2736
Number of pages7
JournalBiosensors and Bioelectronics
Issue number11
Publication statusPublished - 2007 May 15


  • Dielectrophoresis
  • Microfluidic device
  • Microparticles
  • Sandwich immunoassay
  • Separation

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Biomedical Engineering
  • Electrochemistry


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