On-chip integration of sequential ion-sensing system based on intermittent reagent pumping and formation of two-layer flow

H. Hisamoto, T. Horiuchi, K. Uchiyama, M. Tokeshi, Akihide Hibara, T. Kitamori

Research output: Contribution to journalArticle

110 Citations (Scopus)

Abstract

A sequential ion-sensing system using a single microchip was successfully realized. The system developed here involves intermittent pumping of plural organic phases into a microchannel, followed by contact with a single aqueous phase to form a stable organic - aqueous two-layer flow inside the microchannel. Because the plural organic phases created by intermittent flow contain the same lipophilic pH indicator dye but different ion-selective neutral ionophores, different ions can be sequentially and selectively extracted into the different organic phases, where they can be determined by thermal lens microscopy (TLM). We used KD-A3 as the lipophilic pH indicator dye and valinomycin and DD16C5 as neutral ionophores to demonstrate sequential ion sensing of potassium and sodium ions by measuring the deprotonated dye caused by the ion extraction. The integrated microfluidic system proposed here allows multi-ion sensing, which is not easily demonstrated by conventional ion sensor technology using a solvent polymeric membrane. The minimum volume of single organic phase needed to obtain an equilibrium response without dilution by cross dispersion of two organic phases was ca. 500 nL in our system, indicating that the required amounts of expensive reagents in one measurement could be reduced to 1.7 ng and 2.8 ng for the dye and ionophore molecules, respectively.

Original languageEnglish
Pages (from-to)5551-5556
Number of pages6
JournalAnalytical Chemistry
Volume73
Issue number22
DOIs
Publication statusPublished - 2001 Nov 15
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry

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