VS-SVET Sweeping Vibrating Electrode Technique
Description
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VS-SVET generates images of local currents by measuring voltage fields in solution
- It uses a Pt/Ir microelectrode to map the voltage field in solution from local current events, such as pitting corrosion or galvanic couples.
- The SR 7230 ensures superior signal measurement allowing for high resolution measurements.
Applications and Software
The vibrating electrode scanning technique uses a single wire to measure the voltage drop across the solution. This voltage drop is the result of local current on the surface of a sample._cc781905-5cde -3194-bb3b-136bad5cf58d_The measurement of this voltage in images of the solution of the current on the surface of the sample. The current can occur naturally from a biological or corrosion process, or the current can be controlled externally using a galvanostat.
A piezo unit vibrates the probe in the Z direction (axis parallel to the sample). The amplitude of vibration can be only tens of microns from peak to peak._cc781905-5cde-3194-bb3b -136bad5cf58d_This small vibration provides a very small voltage to measure.
Therefore, the electrometer gets the response (signal + noise) in the probe. The output obtained from the electrometer is then input to a Lock-In amplifier. This , in turn, uses a phase detector along with a reference to the same vibration frequency to extract the small AC signal from the entire measured response. The VersaSCAN takes advantage of leading noise characteristics in Ametek industry's Signal Recovery 7230 blocking amplifier to provide superior measurement of these small signals.
The voltage is recorded and the probe is repositioned. The results of a data map are displayed as the voltage is displayed as a function of position.
A key application of SVET is to study the corrosion process of bare metals. These metals can be galvanic pairs or can occur from local non-uniform corrosion events, such as pitting or cracking.
The series of time-lapse experiments provide the ability to literally watch corrosion events occur, as different areas passivate and activate.
Furthermore, there are many applications and references for the use and results of SVET used in biological systems.
- Measure the localized voltage gradient between the tip and the substrate to determine the localized current density.
- Developed for the analysis of non-uniform corrosion events, such as pitting, welding and galvanic pairs.
- Capable of generating temporal resolution images when scheduled as a sequence.