What Is A Dissolved Oxygen Sensor And When Should We Use It?

The electrochemical method usually uses the dissolved oxygen sensor to conduct oxygen measurement. It is the most critical criterion for determining the efficiency of the water in our surroundings and the need for the survival of higher aquatic creatures. Through film, the dissolved oxygen content is measured by its diffusion rate. The dissolved oxygen sensor is highly in demand and has a significant role in monitoring environmental conditions, especially aquaculture development.

For deployment measurements and process monitoring, the dissolved oxygen sensor is connected to a metre for spot field and laboratory applications or to a data-logging, processes monitor, or transmitter. The pollutant in the water is often responsible for clogging the electrochemical sensor’s film.

Dissolved oxygen as a water conductivity sensor enters the water by absorption directly through the atmosphere, photosynthesis as a bi-product of aquatic plant life, and another factor that causes rapid movements in the surroundings. An intelligent dissolved oxygen sensor’s significant duties are automatically monitoring water temperature, dissolved oxygen concentration, recalibrating the device, and cleaning the probe. A good design structure can achieve the measurement system’s safety, accuracy, stability, and long service life.

What Constitutes A Dissolved Oxygen Sensor?

The electrode of a water conductivity sensor is composed of a coated primary battery electrode or polarographic electrode. It has oxygen as its cathode and lead as its anode because the sensor was initially made out of an oxygen battery. Because oxygen must be discharged through metal, silver wire with electrolyte within and a coating from the outside is used for isolation. Zirconium oxide is the main component in constructing the sensor inorder to make use of the sensor’s thermal driven electrochemical fuel cell. Two platinum electrodes are mounted on zirconium oxide to link the output voltage to a control module.

Factors Influencing Water Dissolved Oxygen Levels

The following factors determine the quantity of dissolved oxygen in water:

Depth of the water

When the water concentration increases, the wind creating waves on the surface increases the DO due to the shallow water surface. Colder and deeper freshwaters may contain more significant amounts of dissolved oxygen due to microbial breakdown, lack of air interaction for transmission, and the unavailability of photosynthesis.


Because bacteria feeding on organics and decaying materials need oxygen in their respiration, the lower bioactivity of microorganisms in water results in a greater concentration of DO.


Since oxygen molecules travel very slowly at lower temperatures, a body of water with lower temperatures may hold more dissolved oxygen. Hot water allows gaseous oxygen to circulate freely and evaporate into the atmosphere.

Atmospheric pressure

Retaining more dissolved oxygen can be allowed in higher atmospheric pressure. Water can hold more oxygen molecules when there is increasing pressure above.


Since salts impact the solubility of gases, they are effectively driven out of the water; lower salinity adds to a greater concentration of DO.

What Are The Benefits Of Using A Dissolved Oxygen Sensor?

Monitoring dissolved oxygen and treating it to maintain correct DO levels in many water purification processes are critical duties. Although dissolved oxygen is required for life and treatment, it may also be harmful, causing oxidation, ruining machinery, and impairing product quality. Dissolved oxygen has an impact on:

Regulatory Compliance

Before wastewater may be released into a stream, lake, river, or canal, it must frequently meet specified DO concentrations to ensure compliance with laws. Dissolved oxygen is required in healthy waters that can sustain life.

Process Control

DO concentrations are essential for controlling biological wastewater treatment and the biofiltration stage of drinking water production. In specific industrial uses (for example, power generation), DO is harmful to steam creation and must be eliminated, as well as its concentrations.


Water that lacks adequate DO becomes nasty and harmful, impacting the environment, drinking water, and other items. To quantify DO, this approach utilises light and luminous substances. These conductors are easier to manage and maintain their calibration and therefore are not affected by hydrogen sulphide or other gases. They provide accuracy, consistency, and repeatability, as well as 60-second reaction times.

How To Maintain a Dissolved Oxygen Sensor?

Every one to three months, they should carry out maintenance operations. It involves cleansing the probe’s anode/cathode assembly, refilling the electrolyte solution, then changing the membrane cover is all part of the process. Electrolyte and membrane cap change is required for dissolved oxygen probes every two weeks to six months, depending on use and sample type. After its ability to decrease oxygen is gone, the electrolyte must be supplied regularly. If the membrane gets discoloured, wrinkled, or ripped, you should change the membrane cap. The first step in troubleshooting if dissolved oxygen measurements become irregular or empirically validated is to execute probe maintenance operations.


The dissolved oxygen sensor is a device that is used to evaluate the environmental quality of water by detecting the quantity of oxygen present in it.