The Scanning Vibrating Electrode Technique uses a single wire to measures voltage drop in solution. This voltage drop is a result of local current at the surface of a sample. Measuring this voltage in solution images the current at the sample surface. Current can be naturally occurring from a corrosion or biological process, or the current can be externally controlled using a galvanostat. A piezo unit vibrates the probe in Z-direction (axis parallel to the sample). The amplitude of vibration may be only 10s of microns peak-to-peak. This small vibration provides a very small voltage to be measured. Therefore, the response (signal + noise) at the probe is then gained by the electrometer. The gained output of the electrometer is then input to a Lock-In Amplifier. This, in turn, uses a phase detector along with a Reference at the same frequency of vibration to extract the small AC signal from the entire measured response. The VersaSCAN capitalizes on Ametek’s industry-leading Noise Characteristics of the Signal Recovery 7230 Lock-In Amplifier to provide superior measurement of these small signals. The voltage recorded and the probe is repositioned. A data map results as voltage versus position are displayed. A key application of SVET is to study corrosion process of bare metals. These metals could be galvanic couples or these could occur from local non-uniform corrosion events, such as pits or crevices. Time-lapse experiment series provide the capability to literally watch the corrosion events happen – as different areas passivate and activate. Additionally, there are many applications and references for the use and results of SVET used in biological systems.
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- Measures localized voltage gradient between tip and substrate for determination of localized current density.
- Developed for analysis of non-uniform corrosion events, such as pits, welds and galvanic couples.
- Capable of Time-Resolved Imaging when programmed as a sequence