title: Individual nanotube-based needle nanoprobes for electrochemical studies in picoliter microenvironments.
abstract: We report the fabrication and characterization of individual nanotube-based, long and straight needle nanoprobes for electrochemistry and the study of their applicability and behavior in microenvironments. The needle nanoprobe, with a nanoscale ring-shaped Au electrode at the tip of the needle serving as the active electrode, was characterized by electrochemical current measurement and cyclic voltammetry and analyzed with electrochemical models. Such a needle nanoprobe, in combination with another metal-coated nanowire as a reference electrode, was further used, for the first time, for local electrochemical sensing inside microdroplets having volumes down to a few picoliters. We explain the acquired voltammetric behaviors of redox-active molecules in confined microscale environments and reveal a unique electrochemical mechanism which allows the regeneration of the redox-active molecules and the establishment of a stable reference potential in the microenvironments.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, Illinois 61801, USA.
authors.forename: Kyungsuk
authors.initials: K
authors.lastname: Yum
authors.forename: Han Na
authors.initials: HN
authors.lastname: Cho
authors.forename: Jie
authors.initials: J
authors.lastname: Hu
authors.forename: Min-Feng
authors.initials: MF
authors.lastname: Yu
mesh_terms: D004563:Electrochemistry / Q000295:instrumentation*; D043942:Nanotubes / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size