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NOx- Biosensor

The NOx- biosensor.
The NOx- or NO2- ions diffuses over the ion-permeable membrane. The active denitrifying ba...
The signal from the biosensor is generated by the built-in N2O transducer. The resulting sensor signal is proportional to ...
Calibration of a sensor in the range from 0-5 uM demonstrating the high sensitivity of the sensor to NO3-.
The Unisense NOx- is an ideal tool to study the dynamics of nitrification/denitrification in waste water. The ...
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Measure NOx- or NO2-

The NOx- sensor is an excellent tool for on-line measurement in experiments where resolution of time and concentrations is important. The sensitivity is high and the sensor can measure concentrations below 0,5 µM. The NOx- sensor has a good stability over days and works at full oceanic salinity.

Compared to conventional NO3-/ NO2- analyzing systems (HPLC and ion chromatography) the Unisense NOx- biosensor is a high quality research tool and a low cost alternative. The NOx- biosensor can measure directly in soil slurries, drinking water, wastewater and water from lakes, streams and seas and it can be applied in a wide variety of research applications including:

  • Wastewater research
  • Environmental sciences
  • Biotechnology

Sensor technology:

The biosensor consists of an electrochemical N2O transducer, equipped with a biochamber, which is mounted on the transducer by a simple locking ring. There are two versions of the bio chamber, one for nitrate/nitrite (NOx-) measurements and one for nitrite (NO2-) measurements.

The NOx- or NO2- ions enter the sensor by molecular diffusion through the ion-permeable membrane. The active denitrifying bacteria reduce NOx- or NO2- to N2O, which is detected electrochemically by the N2O transducer. The electron donors for this de-nitrification are contained in a nutrient reservoir within the sensor. The bacteria are therefore continually growing, making the biosensor much more robust than enzyme-based biosensors.
The electrochemical component (N2O transducer) and the biological component of the sensor are separated by a silicone membrane, which only allows gases to penetrate. Therefore, the only interfering substance is external N2O, which is normally present in negligible concentrations in natural environments.

This principle allows the sensor to measure NOx- or only NO2- in chemically and biologically complex environments, e.g. seawater, waste water, liquid manure, mud, and soil extractions, without interference from substances other than N2O.

Ordering Information 
 Standard Glass Sensor  Outside tip diameter
 NOx- biosensor  Macrosensor
 NO2- biosensor  Macrosensor
 NOx biochamber  Replaceable bioreaction
 chamber for nitrate
 NO2- biochamber  Replaceable bioreaction
 chamber for nitrite


Find a complete list of NOx- macrosensor specifications below and possible microsensor customizations and adaptations under Related Products found to the right.

View NOx- Biosensor Specifications

Technical information

View sensor specifications

Related products

Sensor Customization

Bollmann,A. et al (2005), Influence of starvation on potential ammonia-oxidizing activity and amoA mRNA levels of Nitrosospira briensis, Applied and Environmental microbiology, 1276 - 1282, vol. 71 Read abstract

Juhler,S. et al (2009), Distribution and Rate of Microbial Processes in an Ammonia-Loaded Air Filter Biofilm, Applied and Environmental microbiology, 3705 - 3713, vol. 75 Read abstract

See all publications
Nitrogen Compound Cycle

Nitrogen Compound Cycle

Unisense microsensors and biosensors are widely used in wastewater research. The N2O microsensor is a unique sensor that allows you to determine dissolved N2O in water samples.

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