pH micro-electrode

pH micro measurements


The Unisense pH micro-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 Unisense pH micro-electrode is the only pH electrode available to measure pH at the micro-scale. The pH of solutions in extremely small volumes can be measured with the Unisense pH micro-electrode. The electrode is also ideal for profiling, sediment and general pH measurements.

The Unisense pH micro-electrode has been used by the world’s leading scientists for decades and is cited in over hundreds of papers in journals such as Nature and Science.


  • Measurement tip size as small as 10 µm
  • Extremely fast T90 response times of less than 3 seconds
  • Suitable for a wide range of applications from biogeochemistry to biomedical to food science


detailed information

Unisense pH-sensor-tipThis 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.


tip diameter sizes
  • pH-10: 10-19 µm
  • pH-25: 20-30 µm
  • pH-50: 40-60 µm
  • pH-100: 90-110 µm
  • pH-200: 180-220 µm
  • pH-200C: 180-220 µm (combination electrode with internal reference electrode)
  • 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 mm
  • pH-NP: 1.6 x 40 mm – needle for piercing


pH/mV meter

Unisense pHmV-Meter_IMGThe Unisense pH microelectrode is supported by the pH/mV meter. This compact and economic one-channel amplifier has excellent signal handling and amplification. The meter also comes with Unisense SensorTrace Logger Software.



reference electrode for pH micro-electrodes

Unisense pH REF-RMReference electrodes from Unisense are simple silver/silver-chloride open-ended electrodes designed to work with potentiometric microelectrodes (e.g. Unisense pH and Redox microelectrodes). For measurements with these sensors, it is important that the measuring sensor is in fluid contact with the reference. For most purposes this can be achieved with a large macro-reference. For some applications the sample is so small (e.g. a droplet) that the reference must be as small as the measuring microelectrode.

For laboratory use, Unisense provides a macro reference electrode from Radiometer Analytical. Our micro-sized reference electrodes are glass electrodes manufactured at Unisense. For in situ use, Unisense manufactures a pressure-compensated macro electrode.





Portillo,M.C. et al (2010), Moonmilk Deposits Originate from Specific Bacterial Communities in Altamira Cave (Spain), Microbial ecology, 1 – 8, vol.

Liniger,M. et al (2003), Cleavage of trypanosome surface glycoproteins by alkaline trypsin-like enzyme (s) in the midgut of Glossina morsitans, International journal for parasitology, 1319 – 1328, vol. 33

Kamp,A. et al (2006), Anaerobic sulfide oxidation with nitrate by a freshwater Beggiatoa enrichment culture, Applied and Environmental microbiology, 4755 – 4760, vol. 72


manual & docs

related products