Quantitative probing of surface charges at dielectric-electrolyte interfaces

Weihua Guan, Nitin K. Rajan, Xuexin Duan, Mark A. Reed

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


The intrinsic charging status at the dielectric-electrolyte interface (DEI) plays a critical role for electrofluidic gating in microfluidics and nanofluidics, which offers opportunities for integration of wet ionics with dry electronics. A convenient approach to quantitatively probe the surface charges at the DEI for material pre-selection purpose has been lacking so far. We report here a low-cost, off-chip extended gate field effect transistor configuration for direct electrostatic probing the charging status at the DEI. Capacitive coupling between the surface charges and the floating extended gate is utilized for signal transducing. The relationship between the surface charge density and the experimentally accessible quantities is given by device modeling. The multiplexing ability makes measuring a local instead of a globally averaged surface charge possible.

Original languageEnglish (US)
Pages (from-to)1431-1436
Number of pages6
JournalLab on a Chip
Issue number7
StatePublished - Apr 7 2013

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Biochemistry
  • General Chemistry
  • Biomedical Engineering


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