title: Glass nanopore-based ion-selective electrodes.
abstract: Glass nanopore-based all-solid-state ion-selective electrodes (ISEs) have been developed to probe the distribution of ionic species at micro- or submicrometer-length scales, e.g., mapping of ion flux through micrometer-sized pores. The all-solid-state ISE was fabricated by sealing a conically etched platinum wire (d = 25-microm; radius of etched tip <10 nm) into a soda lime glass capillary. A Pt disk was exposed by gentle polishing the glass and the disk etched to form a conical pore of submicrometer dimension (radius < approximately 500 nm; depth < approximately 30 microm). Ag was electroplated on the Pt electrode in the pore and gently chloridated to obtain a AgCl/Ag layer within the pore. The AgCl/Ag layer-coated ISE was used as a highly selective Cl- probe in scanning electrochemical microscope experiments to map the ion flux through a micropore. The same ISE was also used as the base transducer of the neutral carrier-doped solvent polymeric membrane. The optimized polymer membranes used for the glass nanopore-based all-solid-state ISE require a higher ratio of plasticizer/polymer (9/1) compared to those for conventional ISE (2/1). An ISE based on deposition of an IrO2 layer at the base of a glass nanopore electrode exhibited a highly sensitive response (79.7 +/- 2.3 mV/pH) to variations in pH and could be used for approximately 3 weeks.
authors.affiliation: Chemical Sensor Research Group, Department of Chemistry, Kwangwoon University, Seoul 139-701, Republic of Korea.
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Shim
authors.forename: Juneho
authors.initials: J
authors.lastname: Kim
authors.forename: Geun Sig
authors.initials: GS
authors.lastname: Cha
authors.forename: Hakhyun
authors.initials: H
authors.lastname: Nam
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: White
authors.forename: Henry S
authors.initials: HS
authors.lastname: White
authors.forename: Richard B
authors.initials: RB
authors.lastname: Brown