Alternative configuration scheme for signal amplification with scanning ion conductance microscopy

Abstract

Scanning Ion Conductance Microscopy (SICM) is an emerging nanotechnology tool to investigate the morphology and charge transport properties of nanomaterials, including soft matter. SICM uses an electrolyte filled nanopipette as a scanning probe and detects current changes based on the distance between the nanopipette apex and the target sample in an electrolyte solution. In conventional SICM, the pipette sensor is excited by applying voltage as it raster scans near the surface. There have been attempts to improve upon raster scanning because it can induce collisions between the pipette sidewalls and target sample, especially for soft, dynamic materials (e.g., biological cells). Recently, Novak et al. demonstrated that hopping probe ion conductance microscopy (HPICM) with an adaptive scan method can improve the image quality obtained by SICM for such materials. However, HPICM is inherently slower than conventional raster scanning. In order to optimize both image quality and scanning speed, we report the development of an alternative configuration scheme for SICM signal amplification that is based on applying current to the nanopipette. This scheme overcomes traditional challenges associated with low bandwidth requirements of conventional SICM. Using our alternative scheme, we demonstrate successful imaging of L929 fibroblast cells and discuss the capabilities of this instrument configuration for future applications.

Large-scale and non-contact surface topography measurement using scanning ion conductance microscopy and sub-aperture stitching technique

“…For instance, Novak et al successfully measured the dynamic interaction between a nanoparticle and a living cell by utilizing an additional fast shear piezo-actuator to accelerate the withdrawing of SICM probe [47]. Kim et al presented an improvement on imaging speed by designing a novel configuration for the signal amplification of SICM [48]. Our future work will focus on introducing these new techniques into the proposed large-scale measurement method to further reduce the scan time and then expand the application of this method.…”

Development of high-speed ion conductance microscopy

“…Several groups have attempted to increase v z [13,[34][35][36][37][38]. One of approaches used is to mount a shear piezoactuator with a high resonant frequency (but with a small stroke length) on the Z-scanner and this fast piezoactuator is used as a 'brake booster' [34,35]; that is, this piezoactuator is activated only in the initial retraction phase where the tip is in close proximity to the surface.…”

“…This method could cancel an overshooting displacement and therefore increase v z by 10-fold. Another approach is to increase B id by the improvement of the SNR of current signal detection with the use of a current-source amplification scheme [37] or by the use of AC bias voltage between the electrodes (the AC current in phase with the AC bias voltage is used as an input for feedback control) [13,38]. This bias voltage modulation method is further improved by capacitance compensation [14].…”

Dimensional comparison between amplitude-modulation atomic force microscopy and scanning ion conductance microscopy of biological samples

“…[6][7][8][9] In principle, SICM measurements are based on changes in ion conductance between two electrodes, monitored via a glass nano-pipette. [10][11][12] A schematic of a SICM system is shown in Fig. 1(b).…”