Dual-barrel electrodes

In experiments with dual-pipette electrodes, the purpose of silanizing the outer glass wall is to prevent the formation of an aqueous film between the two pipettes and mixing of the filling solutions. The procedure is similar to the above except that argon should be passed through both barrels of the pipette. 

Scanning electrochemical cell microscopy (SECCM) uses a capillary with double compartment (dual barrel capillary) pulled to a sharp opening (Fig. 13b) as scanning probe [36]. Both compartments of the capillary are filled with the electrolyte solution, and a quasi-reference counter electrode (QRCE) is inserted in each compartment (Fig. 13a). 

An alternative route to fabrieating SECM-SICM probes with smaller electrode dimensions has been explored by Takahashi and co-workers, who developed a simple proeedure for making dual-barrelled probes from theta capillaries. In this proeess, one of the barrels of a pulled capillary is filled with carbon via the pyrolytic decomposition of a hydrocarbon gas feed. 

Figure 14.15 shows a photograph of commonly used microelectrodes and miniaturized reference and counter electrode. Note that even a dual microelectrode (double-barrel electrodes68) can be used in the robotic system.69... 

For high impedance electrodes, e.g., liquid membrane ion-selective tips (39), another method is essential. Using techniques borrowed from electrophysiology, it is possible to construct dual tips from theta glass (Chapter 3). One barrel of the double tip can be used for the liquid membrane, and the other may be filled with a low melting point metal such as gallium to make a voltammetric sensor (41). 

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