The Unisense pH electrode, here shown with a tip diameter of 100 µm.
The pH microelectrode can be mounted with a steel needle to make the glass sensor strong in the longitudinal axis.
The pH microelectrode must be connected to a reference electrode to obtain a sensor signal. Here robust reference electrode is sho...
The pH microelectrode signal must be amplified by a Unisense amplifier e.g. the laboratory pH/mV-Meter.
The pH sensor tip consists of two pieces of glass glued together. The pH glass is proton sensitive, thus the sensing part of the s...
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Miniaturized pH electrode
The Unisense pH electrode offers you a fast and reliable research tool. With tip sizes down to 10 µm, you can complete high resolution and non-destructive microprofiles in a wide range of microenvironments.
The pH microelectrode is designed for research applications within:
- Environmental sciences
- Biomedical sciences
- Biotechnology
- Food science e.g. cheese production
- Microbiology
Microelectrode technology:
This microelectrode is a miniaturized conventional pH electrode based on selective diffusion of protons through pH glass, and the determination of potentials between the internal electrolyte and a reference electrode. The reference electrode can be either external (separate electrode) or internal; however, we only recommend internal references in applications where it is not possible to place two electrodes in the sample.
Ordering Information
Standard Glass Sensor |
Outside tip diameter |
pH-10 |
8-12 µm |
pH-25 |
20-30 µm |
pH-50 |
40-60 µm |
pH-100 |
90-110 µm |
pH-200 |
180-220 µm |
pH-500 |
400-600 µm |
pH-500C |
400-600 µm (combination electrode with internal reference electrode) |
pH-MR |
400-600 µm |
pH-N |
1,1 x 40 mm - needle sensor |
pH-NP |
1,6 x 40 mm - needle sensor for piercing |
Find full pH microelectrode specifications, including warranty and expected life time, below and possible microelectrode customizations and adaptations under Related Products found to the right.
Print
pH sensor
Note: BNC connections are discontinued as of August 1. 2010. Adapters are available from Unisense to support compatibility to legacy sensors and instrumentation.
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Standard |
Options |
Extra price for
option selection |
Glass electrodes |
Outside tip
dimensions
(diameter x length of
sensitive pH glass) |
PH-10 (10-19 x 50-100 µm)
PH-25 (20-30 x 75-125 µm)
PH-50 (40-60 x 100-200 µm)
PH-100 (90-110 x 150-250 µm)
PH-200 (180-220 x 250-350 µm)
PH-500 (400-600 x 400-800µm)
PH-500C (400-600 x 400-800µm)
PH-MR (400-600 x 400-800µm)
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Diameter 20mm from tip |
< 2mm |
< 1mm |
10% |
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Diameter 50mm from tip |
8mm |
< 2mm |
20% |
Needle electrodes |
Needle length |
40mm
Not suitable for piercing of septum |
See Customization |
+ 10% |
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Needle diameter |
1.1mm
Not suitable for piercing of septum |
See Customization
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+ 10% |
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Position of sensing tip |
Exposed, but protected |
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All electrodes |
Total length |
150-200mm |
70-350mm |
20-50% |
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Shaft diameter |
8mm |
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Shaft protection
diameter* |
11mm |
Can be omitted |
- |
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Cabling etc. |
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Cable |
Habia |
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Cable length |
1.5-2m |
0-20 m |
Yes, depends on length |
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Connector |
LEMO |
BNC adapter |
Yes, ordered separately |
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In situ gold pin
connectors** |
No |
Yes |
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Characteristics |
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Internal reference |
Only as pH-500C*** |
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Water proof |
Yes |
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Temperature range |
-10o-60o |
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Temperature range tip |
-10o-90o |
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Guaranteed life time |
3 months |
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Expected life time |
> 6 months |
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Spatial resolution |
about 100-250 µm
(PH-500 about 500 µm) |
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Range |
pH 2-10 (linear 4-9) |
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Detection limit |
0.01 pH unit |
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Response time (90%) |
< 10s (from pH 7 to pH 4) |
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Response |
Log linear |
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*
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When mounted with in situ mini connectors, the shaft has no protection mounted, but fits directly into the in situ sensor mounts with pressure compensation. In situ sensors have a standard length of 140 mm ± 5 mm. |
**
|
Due to the small area of the pH-sensitive glass, Unisense pH10 electrodes typically have an inner resistance of 109 Ohm. Therefore the millivoltmeter input resistance must be at least 1013 Ohm.
|
***
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Construction of the sensor with an internal reference involves creation of a liquid junction 1 mm from the electrode tip. During measurements this liquid junction has to be submersed in the medium in order to complete the measurement circuit. |