A dielectric biosensor using the capacitance change with AC frequency integrated on glass substrates

Jongin Hong, Dae Sung Yoon, Myung Il Park, Jongwan Choi, Tae Song Kim, Geunbae Im, Sanghyo Kim, Y. Eugene Pak, Kwangsoo No

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Glass-based microchannel chips were fabricated using photolithographic technology, and Pt thin-film microelectrodes as dielectric biosensors were integrated on them. From capacitance-frequency measurements at various interelectrode distances and ionic concentrations, a significant difference between deionized (DI) water and tris-ethylenediaminetetraacetic acid (EDTA) (TE) buffer was observed in the low-frequency region. Although the capacitance (CM) of the DI water decreased as the interelectrode distance increased, that of the TE buffer was similar up to a frequency of 100 Hz, after which it was spilt in the same manner as the DI water above 100 Hz. As the ionic concentration increased, the CM of the TE buffer increased and the slope in the low frequency region changed from -0.875 to -0.425. The point where the slope changed shifted towards the frequency increase. These observations were clarified from the viewpoint of interfacial phenomena, such as the electrical double layer and Faradaic reactions, the dielectric constant related to conductivity, and the capacitance inversely proportional to the interelectrode distance. The addition of deoxyribonucleic acid (DNA) molecules (10ng/ul) increased the capacitance and dielectric loss in the TE buffer at low frequency. It is feasible to use dielectric properties for the rapid and direct detection of biomolecules, particularly DNA molecules, without using labels or indicators.

Original languageEnglish
Pages (from-to)5639-5645
Number of pages7
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Issue number8 A
Publication statusPublished - 2004 Aug
Externally publishedYes


  • Capacitance
  • DNA detection
  • Dielectric biosensor
  • Dielectric loss
  • Electrical double layer

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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