Micro-/Nanopipette Techniques

Micro-/Nanopipettes are used in SECM-related techniques:

  • Scanning ion conductance microscopy (SICM)
  • Scanning micropipette contact method (SMCM)
  • Scanning electrochemical cell microscopy (SECCM)

The pipettes are filled with electrolyte solution and an Ag/AgCl wire is inserted into the pipette which acts as a quasi-reference-counter electrode (QRCE). For measuring ion conductance currents, the current between the QRCE inside the pipette and one in the bulk solution or second pipette barrel inside a theta capillary is determined.

SICM

In SICM the ion conductance current between one quasi-reference-counter electrode (QRCE) inside the micropipette and one in the bulk solution is measured. The substrate is immersed in electrolyte. Upon approaching a surface, the ion conductance current decreases due to hindered diffusion between micropipette opening and the surface. This allows non-contact high-resolution topography imaging.

SMCM and SECCM

In SMCM and SECCM the solution-filled micropipette is operated in air, as well as the substrate. At the opening of the micropipette a droplet is formed. At close proximity to the substrate surface, the droplet creates a miniature electrochemical cell by locally wetting the surface.

In this electrochemical cell where the substrate is connected as the working electrode (WE) and the Ag/AgCl wire as the QRCE, spatially resolved localized electrochemical techniques, such as:

  • Micro-CV and micro-fabrication for conductive polymers
  • Localized characterization of battery materials
  • Micro-EIS and micro-Tafel for localized corrosion studies
  • Combined electrocatalysis and topography imaging for nanomaterials

Check out our micropipette holder for SMCM and theta pipette holder for SECCM.

SECM - SICM

Using theta-micropipettes (double-barrel micropipettes) enables the combination of SECM and SICM in one scan. One barrel is filled with electrolyte solution and an Ag/AgCl wire is inserted. In the other barrel, carbon is deposited to create a microelectrode tip. Topography imaging is performed by measuring the ion conductance current through the electrolyte-filled barrel (SICM). Electrochemical properties are simultaneously probed by the microelectrode (SECM).

Top View of Theta Pipette