Scanning ion conductance microscopy SICM

Other local probe techniques to be discussed, of an electrochemical nature, which rely on much of the same instrumental technology, are scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM). 

Scanning micropipette microscopy (SMM) Scanning micropipette molecule microscopy (SMMM) Scanning ion conductance microscopy (SICM)... 

SECM associated with scanning ion conductance microscopy (SICM) requires a double tip, on one side of which is a conventional microdisc electrode and on the other side is a narrow pipette filled with electrolyte and an electrode that measures ionic conductance through the mouth of the pipette with respect to another electrode in the bulk solution. When the pipette mouth is within one pipette tip radius away from the sample surface, the conductance varies sufficiently to be used as a control signal to maintain the z-position of the tip during the scans, thereby affording constant-distance SECM operations [133,134]. This methodology is fast and apparently less-challenging to implement than shear force SECM, but it requires the fabrication of double-barrel tips in which one channel is left empty and the other is filled with a conventional microdisc. 

Scanning ion-conductance microscopy (SICM) was initially developed to obtain topographical information on delicate and fragile samples, typically biological samples, immersed in liquid solution in a noncontact and noninvasive way [33]. SICM employs a hollow capillary as scanning probe instead of a microelectrode. 

Chen, C.-C., and L. A. Baker, Effects of pipette modulation and imaging distances on ion currents measured with scanning ion conductance microscopy (SICM), Analyst, Vol. 136, 2011 pp. 90-97. 

Zhukov, A. Richards, O. Ostanin, V. Korchev, Y Klenerman, D., A hybrid scanning mode for fast scanning ion conductance microscopy (SICM) imaging. Ultramicroscopy 2012,121,1-1. 

Nadappuram, B. P. McKelvey, K. A1 Botros, R. Colbnm, A. W. Unwin, P. R., Fabrication and characterization of dual function nanoscale pH-scanning ion conductance microscopy (SICM) probes for high resolution pH mapping. Analytical Chemistry 2013, 85, 8070-8074. 

At smaller values of the tip-substrate separation distance, d, feedback and hindering effects, as those observed in the feedback modes at amperometric tips, perturb the transport processes. The tip then starts to interfere with the source, which complicates the quantitative data analysis without numerical modeling.Such perturbing effects are not observed when passive probes such as potentiometric " or biosensor microelectrodes are used, but then the positioning of these substance-selective sensors is difficult. An alternative would be to consider the use of the scanning ion conductance microscopy (SICM). Indeed, recently, the SICM afforded the opportunity to image and quantify precisely local K+ and Cl ionic fluxes. ... 

The pipette resistance is another important parameter to be measured if the pipette is to be used in kinetic experiments (and also for resistive-pulse sensing or scanning ion conductance microscopy, SICM). The total pipette resistance comprises of two components, that is, the... 

Three major detecting methods of electrochemistry have been adapted for SECM studies. They are voltammetry, potentiometry, and conductometry. It must be mentioned here that scanning ion conductance microscopy (SICM) sometimes considered rather as an individual scanning probe microscopic technique than member of the SECM methods. Accordingly, we discuss shortly the SECM properties of the three detection techniques trying to show the major differences. 

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