Experimental devices used for ultrasound assistance to electroanalytical techniques

Experimental devices used for ultrasound assistance to electroanalytical techniques 

The simplest way to assist electrochemical techniques with US is by using a bath to immerse the electrochemical cell, as proposed by Lorimer et al. [154] (see Fig. 8.15A). These authors used a three-compartment thermostated voltammetric cell consisting of a platinum flag (the counter electrode), a saturated calomel electrode (the reference electrode) and a rotating disc (the working electrode). Although an ultrasonic bath affords less accurate control of US irradiation, it affords a tenfold current increase in sonovoltammetry [167]. 

US applications, where the ultrasonic field can induce potential oscillations [169]). Somewhat less common is the use of split cell arrangements where a glass separator [145] or a polymer coating [170] is used to separate the compartments in which the ultrasonic tip and the electrodes are immersed. 

The flow generated by US application in the side-on position is similar to that observed at a channel electrode with the mass transport of electroactive material similar to that of a convective flow over a stationary plate. This geometry provides well-defined sonovoltammetric signals for quantitative purposes. The speed of the flow passing over the electrode has been measured to be between 50 and 170 cm/s [173,174]. 

Another possibility is adapting the titanium tip of the US transducer (Fig. 8.16C) for use as a working electrode (a sonotrode ). The simplest case is the use of the titanium tip itself as electrode [175] however, anodic currents are not possible owing to the formation of a Ti02 layer [176]. More recently, sonotrodes have been prepared by directly embedding a platinum electrode into the horn tip this provides extremely high limiting currents for diffusion layer thicknesses of less than 1 pm, even at low US intensities [133]. The operation 

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