Dissolved oxygen meters measure the amount of oxygen dissolved in a medium.
Dissolved oxygen refers to the measure of a percentage of oxygen that dissolves in a given medium. The measurement can be determined with a dissolved oxygen meter --- a device that uses oxygen-sensing probes. The probes contain optical fluorescence sensors, galvanic sensors or polarographic sensors.
Optical Fluorescence
An optical fluorescence sensor is coated with fluorescent properties. Light is exposed to this coating, producing a light and subsequent afterglow of fluorescence. The oxygen level of a medium is measured based on the duration of the afterglow.
Galvanic Sensor
A galvanic sensor acts as a battery and is able to generate power without external voltage. Galvanic probes contain an anode and cathode in an electrolyte. Oxygen enters the electrolyte via a membrane, which generates voltage between the anode and cathode. This difference in potential voltage is used to measure the amount of dissolved oxygen.
Polarographic Sensor
Polarographic sensors operate in a fashion similar to galvanic sensors, but require a connection to an external voltage source. The difference in voltage potential between the anode and cathode yields a measurement of the dissolved oxygen.
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