Probe
SECM UME Probes
Ultra Micro Electrodes for SECM/ac-SECM/ic-SECM
Choice of fused silica and pulled capillary SECM probes covering a range of sizes form 1 to 25 µm diameter
SECM uses an UltraMicroElectrode (UME) to measure the local electrochemical activity of an interface. When selecting an SECM probe there are a number of characteristics which should be considered.
Probe diameter
The diameter of the active area of the probe is directly related to the resolution of the SECM measurement. Ideally, the probe should be equal to or smaller than the feature of interest to achieve the sharpest images. It is possible to use a probe with an active diameter larger than the feature of interest, however, the resulting image will be broader, and overlap from nearby features may be apparent.
RG Ratio
The RG ratio is given by RG=R/r where R is the radius of the insulating sheath of the probe, and r is the active area of the electrode. The RG ratio should typically be around 10 to achieve optimal results. When the RG ratio is too large, the redox mediator has a large distance to diffuse to reach the active area. This restricts how close the probe can approach the sample surface, restricting the sensitivity of the technique. On the other hand, when the RG ratio is too small the diffusion of the redox mediator to the probe is poorly restricted, resulting in similar responses for active and inactive regions again reducing the sensitivity of the technique.
Active Material
The active material of the probe is important in determining the sensitivity of the measurement. The most popular material for SECM probes is platinum. Platinum is relatively inert and compared to other materials the surface is easily prepared for use. Furthermore, platinum is typically more sensitive than other electrode materials.
Two different types of Platinum SECM UME are available: Fused Silica Based SECM Probes and Capillary Based SECM Probes.
Capillary based SECM Probes
- Designed for use with dc-SECM, ac-SECM
- The 1, 2, and 5 µm probes should NOT be used for ic-SECM under any conditions
- Lower cost
- 1, 2, 5, 10, 15, 25 µm diameter available
Fused silica based SECM Probes
- Designed for use with dc-SECM, ac-SECM and ic-SECM
- Robust construction
- 10, 15, and 25 µm diameter available
| Fused Silica-based SECM probes | |
| Electrode Diameter (/µm) | 10, 15 or 25 |
| Nominal RG ratio | 10 |
| Nominal Probe length (/mm) | 80 |
| Connector | 1.5 mm plug |
| OD (/mm) | 4 |
| Electrode material | 99.9% Pt |
| Order size | 1 probe only |
| Compatible instrument | M470, M370 |
| Ordering information | Part number |
| Product | |
| 10 µm Platinum disk | U-23/10 |
| 15 µm Platinum disk | U-23/15 |
| 25 µm Platinum disk | U-23/25 |
| Capillary based SECM probes | |
| Specifications | |
| Electrode Diameter (/µm) | 1, 2, 5, 10, 15 or 25 |
| Nominal RG ratio | 10 (1µm ~ 30) |
| Nominal Probe length (/mm) | 80-95 |
| Connector | 1.0 mm plug |
| OD (/mm) | 2 |
| Electrode material | 99.99% Pt |
| Order size | Box of 5 probes + 1 holder |
| Compatible instrument | 1,2,5, µm probes:M470, SECM150 |
| 10,15,25 µm probes: |
| Ordering information | Part number |
| Product | |
| 1 µm Platinum disk | U-P5/01 |
| 2 µm Platinum disk | U-P5/02 |
| 5 µm Platinum disk | U-P5/05 |
| 10 µm Platinum disk | U-P5/10 |
| 15 µm Platinum disk | U-P5/15 |
| 25 µm Platinum disk | U-P5/25 |
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