redox micro-electrode

micro ORP measurements


With the tip size down to 10 µm, less than 5 seconds in response time, and 1 mV in resolution, the Unisense Redox micro-electrode offers a high quality research tool for reliable and fast measurements.

The micro-electrode construction makes it possible to use the Redox micro-electrode in a broad variety of research fields where non-destructive, fast and accurate measurements are required.

The Unisense ORP 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 5 seconds
  • Measurement resolution of 1 mV
  • Suitable for a wide range of applications from biogeochemistry to biomedical


detailed information

The Redox electrode tip will develop an electrical potential relative to the reference electrode when both electrodes are immersed in the same solution and connected to a high-impedance millivolt-meter e.g. the Unisense pH/mV-Meter. This potential reflects the tendency of the solution to release or take up electrons; also called the Oxidation-Reduction Potential (ORP). The Unisense Redox microelectrode can be used for measurements in salinities from 0 to full ocean strength.


reference electrode for redox micro-electrodes

PageLines-UnisensepHREF-RM.jpgReference 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.

Unisense also manufacture a combination redox and reference micro-electrode. The part numbers are RD-200C and RD-500C. The combination electrodes are recommended for a limited number of applications. Contact the scientists at Edaphic Scientific for further information.


tip diameter sizes
  • RD-10: 8-12 µm
  • RD-25: 20-30 µm
  • RD-50: 40-60 µm
  • RD-100: 90-110 µm
  • RD-200C : 180-220 µm (combination electrode)
  • RD-500: 400-600 µm
  • RD-500C : 400-600 µm (combination electrode)
  • RD-MR: 400-600 µm
  • RD-N: 1.1 mm
  • RD-NP: 1.6 x 40 mm – needle sensor for piercing
  • RD-Eddy: 15-25 µm



Kristensen,E. et al (2011), Contrasting effects of the polychaetes Marenzelleria viridis and Nereis diversicolor on benthic metabolism and solute transport in sandy coastal sediment, Mar Ecol Prog Ser, 125 – 139, vol. 425

Schmidt,O. et al (2011), Novel [NiFe]-and [FeFe]-Hydrogenase Gene Transcripts Indicative of Active Facultative Aerobes and Obligate Anaerobes in Earthworm Gut Contents, Applied and Environmental microbiology, AEM – 05432, vol.

Vilalta,E. et al (2005), Structural heterogeneity in cyanobacterial mats is associated with geosmin production in rivers, Phycologia, 678 – 684, vol. 44


manual & docs

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