Princeton Applied Research-VersaSCAN – Scanning Vibrating Electrode Technique (Model: SVET)

SVET Overview

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.

The VersaSCAN SVET integrates the Base with a Signal Recovery Lock-in Amplifier, a piezo-based vibration module, an electrometer and a single wire- based probe.  The SVET technique measures voltage-drop in solution.  This voltage-drop exists in electrolyte due to local current activity at a sample surface.  SVET adds spatial resolution to applications such as non-uniform corrosion events, such as pits, welds and galvanic couples.  Additionally, there are biological applications to SVET.

• Compatible Lock-in Amplifier:  Signal Recovery 7230

• Capable of both single Line Scans and Area Scans

• Capable of Time-Resolved Imaging when programmed as a sequence

• Can perform Constant-Distance operation in conjunction with a topographic measurement technique, typically OSP

Specifications