Figure 2

Ion current oscillations in a nanopipette induced by nano-precipitation. (a) Electrochemical setup to measure ion current through a quartz nanopipette. All solutions contain 0.1 M KCl and are buffered at pH 7, with 10 mM potassium phosphate in the barrel and 10 mM Tris–HCl in the bath. Zinc chloride is included in the bath at concentrations of 2--20 μM. (b) Configuration causing ion current oscillations. A negative potential in the nanopipette barrel draws zinc cations from the bath into the pore, while phosphate ions are pushed out into the bath. When a precipitate of sufficient size is formed, the pore is blocked and ionic current decreases. (c) Current oscillations in a nanopipette setup with 2 μM zinc chloride in the bath and a potential of 350 mV. Inset: expanded view of one of the open states. From Ref. [37], copyright@2011 American Chemical Society.