SVET Scanning Vibrating Electrode Technique

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.
  • Documents +

  • Specifications +

    Lock-in Amplifier
    Noise Sensitivity 13fA per second
    Frequency Range 1 mHz up to 250 kHz
    Full Scale Sensitivity from 10nV to 1V
    DSP Stability Impervious to temperature drift
    High Mechanical Stability No fan for failure
    Piezo up to 30 microns vibration perpendicular to sample surface
    Gain from 1x to 10,000x in decades
    Material Pt/lr
    Single-element probe
  • Options +

    L-Cell VersaSCAN L-Cell
    • Screws into optical table of VersaSCAN
    • Approximately 1 Liter in volume
    • Level adjustment mechanism
    • Accepts large flat samples and 32-mm diameter mounted samples
    • Recommended for all techniques, particularly LEIS, SVET, SKP, SDC, OSP
    mL-Cell VersaSCAN mL-Cell
    • Screws into optical base of VersaSCAN
    • Approximately 7 mL in volume
    • Level adjustment mechanism
    • Accepts a range of samples including 32-mm diameter mounted samples and non-standard samples
    • Specifically engineered for low-volume SECM applications
    VersaCAM VersaCAM
    Long Working Distance Video Microscope
    • Camera:
      • Color
      • Number of pixels: 795 (H) x 596 (V)
      • Minimum illumination 0.02 lx. F1.2
      • Power: 12V DC ±10%
      • CS-mounted or C-mount with provided adapter
    • Lens:
      • C-Mount
      • Manual focus
    • Display:
      • 8 inch color TFT display
      • PAL & NTSC auto selection
      • 640x480 (307,200 pixels) screen resolution
  • Video +

    Watch video demonstrations of the SVET Scanning Vibrating Electrode Technique

  • Experiments +

    Line Scan A vibrating probe is used to measure the potential field gradient that exists in solution due to local current at your sample’s surface.  A lock-in amplifier discriminates against noise and amplifies the signal. Sequencing in software allows experiments to image how the local current source changes with time. SVET can use the topographic data from SKP or OSP to run in constant-distance mode, but probes must be exchanged.
    Area Scan SVET Area Scans are X-Line Scan experiments at incremented positions in the Y-direction. This XY plane is graphed as a map.
    Natural occuring Current or Applied Current The SVET is capable of measuring potential field gradients as a result of naturally occurring current or through controlled applied currents.  Additional instrumentation, such as a VersaSTAT, would be need to apply such a current to an inert sample, such as gold.