Why Use an Online Dissolved Oxygen Sensor?

In biological processes like fermentation and cell culture, dissolved oxygen (DO) is critical to support proper cell growth. In industrial processes, oxygen is often limited in applications where corrosion is of concern. Online dissolved oxygen sensors enable real-time measurement and control of dissolved oxygen at a predefined set point. It also enables the detection of a leak in the process that result in oxygen infiltration.

Hamilton DO Probes and Sensors

VisiFerm mA RS485

Optical Dissolved Oxygen Sensors

The VisiFamily of optical dissolved oxygen sensors are quickly replacing polarographic installations due to a more robust measurement and minimal maintenance.
Polarographic dissolved oxygen sensor

Polarographic Dissolved Oxygen Sensors

The OxyFamily of traditional polarographic sensors has an industry-leading two hour polarization time and modular design to simplify maintenance.
Dissolved Oxygen Single Use sensors

Single-Use Dissolved Oxygen Sensors

The VisiFerm sensing element can now come pre-installed and gamma irradiated in your favorite single use bag or bioreactor.

What are the Potential Sources of DO Measurement Error?

dissolved oxygen whitepaper

Much has been written about different strategies for proper DO control. However, little information has been publicly available regarding the optimization of the actual measurement accuracy and reducing common sources of process-related error.

Get Hamilton's whitepaper on potential sources of optical dissolved oxygen measurement error and ways to mitigate the impact.

Get the White paper

Polarographic vs. Optical Dissolved Oxygen Probes

For over 60 years, polarographic dissolved oxygen probes have been used to measure DO through the electrochemical reduction of oxygen with a noble metal. More recently optical oxygen has gained prominence by eliminating polarization time, electrolyte, and complicated maintenance, by requiring only a single replacement part.


Do Optical Illustration

Optical Dissolved Oxygen Sensors

The VisiFamily of sensors have a blue LED in the sensor shaft and an oxygen sensitive dye (luminophore) fixed to a glass window in the replaceable sensor cap. The blue light excites the luminophore and then a photodetector in the sensor shaft senses the red light that is returned from the luminophore. A microprocessor in the sensor correlates the emitted blue light and the measured red light to partial pressure of oxygen. This measurement can then be output as a simulated nA signal, 4 - 20 mA, or digital protocol.

See all optical sensors

Do Polarographic Illustration

Polarographic "Clark Cell" Dissolved Oxygen Probes

Classical Clark cell sensors have a platinum cathode and a silver anode that are separated from the sample by a gas permeable membrane. As oxygen diffuses across the membrane it is reduced resulting in a small nA current. The more oxygen the stronger the current. This current is then detected by a separate transmitter which amplifies the signal for process control.

See the DO measurement guide

Download our O2 Measurement Guide

O2 measurement guide

Get a better understanding of dissolved oxygen (DO) measurement and sensors in Hamilton's comprehensive O2 Measurement Guide. This 72-page booklet is intended for anyone with an interest in DO sensor technology or anyone who needs to implement DO probes and sensors in controlled environments such as laboratories and industrial plants. The guide covers the following essential topics:

  • The basics of oxygen and its chemical and physical properties.
  • The physics of dissolved oxygen.
  • Types of DO sensors and how they work.
  • Applications, calibration, and maintenance of DO sensors.

Specific Applications


Hamilton's knowledge base provides a range of explanatory articles, frequently asked questions, and document downloads.
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