The Ionscope’s hopping mode allows imaging of surfaces with high aspect ratios. In hopping mode, the nanopipette is withdrawn to a Z height clear of all topographical features. The pipette is then brought to a point near the surface where the ion current drops by a predefined amount. The Z-axis height location of the surface is measured and the pipette withdrawn back to a safe height.
A proprietary algorithm for adaptive scanning is built in the software to optimise the Z height clear of topographic features during the scan when the sample roughness changes across its surface. Avoiding unnecessary Z travel reduces scan time.
The approach curve mode can be used to study the current-distance characteristics of the probe or can be particularly useful in studying conductivity at surface pores and features imaged with the hopping mode. The Ionscope SICM measures changes in ion current as the pipette nears material interfaces and surfaces.
The superior nano-positioning capabilities of the Ionscope SICM allow the user to specify multiple XY locations on the sample surface, and to define Z heights along with pipette approach and retraction speeds. Multiple conductivity measurements can be made at multiple locations in the same scan.
The manual approach allows precise and reproducible control of the pipette both for measurement and when extracting or introducing materials near specific features. The manual approach is used in drug challenge, electrochemistry studies and for topography-guided electrophysiological measurements.
In manual approach the pipette can be positioned at a single user-defined XY position. The Z piezo is driven to bring the pipette closer to the sample in precise step sizes (≥0.1 nm) of the piezo movement.
Integration with Auxiliary Input
The Openiolabs SPM IOI controller and software support the option to record a signal from an external measurement device and synchronise it for display with the ion current threshold detection point and the corresponding Z measurement on the topography image. The auxiliary input mode can be used in addition to the hopping mode. The auxiliary signal can be displayed in real time via the 2D or 3D topographic displays (and in conjunction with the ion current signal) and is stored in the database. In this manner a range of simultaneous measurements can be recorded for overlay with the topographic image of the sample- for example, the electrochemical measurements close to the surface of the sample.