Methods for measuring dissolved oxygen

Dissolved Oxygen (DO) is the measure of the amount of oxygen that is distributed in a system. Measurements are generally taken in water using a DO probe and meter. When performing dissolved oxygen measurements in the laboratory or in the field, it should be considered which type of DO technology is most suitable to employ.

The measurement of dissolved oxygen is essential in fermentation and in cell culture to guarantee optimal conditions for the cell, since low levels of oxygen concentration can affect growth rate, nutrient absorption, cell morphology and synthesis of metabolism; that is equivalent to a decrease in the quality of the final product. This in the field of pharmacology

Oxygen meters are also used to measure and control the oxygen content at various points in the water circuit of steam boiler installations, in order to avoid metal corrosion caused by the oxidizing power of oxygen. Among other uses, is the care of aquatic ecosystems and more

Today’s analytical equipment generally uses two types of dissolved oxygen sensors: electrochemical and optical.

Optical sensors measure on the principle of fluorescence extinction. A luminophore that is part of the membrane is excited with the light of a blue LED, emitting in turn a red light. Dissolved oxygen in the sample turns off the excitation. In cases in which the presence of oxygen is not present, the useful life and the signal are the best. The intensity and lifetime of the luminescence are inversely proportional to the amount of oxygen present. The duration and intensity of the luminescence is measured with a photodetector and is used to calculate the dissolved oxygen concentration.

For electrochemical sensors, a thin, permeable membrane isolates the sensor elements from water. The oxygen that passes through the membrane is reduced creating a current that the meter converts into a measurement of oxygen concentration.

What Kind of Dissolved Oxygen Meter Should I Choose?

Optical OD technology


  • No waiting time required before measurement (polarization of polarographic sensors).
  • Does not require a minimum flow, so there is less drift in your readings.
  • It is not consumable, so it is not necessary to provide a continuous sample flow / agitation, as in the case of the electrochemical sensor.
  • Requires no membrane or fill solution, reducing maintenance costs over the life of the probe.


  • Higher initial investment than in traditional electrochemical sensors.
  • Response time may be slower.

To know the correct measurement method, the required maintenance, costs and the measurement process must be considered.

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