History and Methodology

The D-Opto utilises a proven fluorescence technology to measure dissolved oxygen.

The D-Opto optical sensor technology has been successfully used in the wastewater industry for over 10 years. Prototype D-Opto environmental sensors have evolved with installations in place for 2 years.

D-Opto was developed due to the requirements of surface water monitoring programs. The unit has been specifically designed to meet the demanding requirements of the environmental monitoring and scientific research sectors, providing long term, accurate and reliable dissolved oxygen measurement.

Why we developed D-Opto optical technology

Traditional Galvanic and Polargraphic sensors have been used to measure dissolved oxygen in water. Galvanic and polargraphic dissolved oxygen sensors utilize chemical electrical signatures. These are based on a semi-permeable membrane covering electrodes that are immersed in an electrolyte. These sensors have been poorly suited to long term reliable and accuracy dissolved oxygen monitoring in lakes streams and rivers.

Downfalls in these technologies

• The membrane and electrolyte requires frequent replacement
• The electrodes are subject to deterioration and “poisoning”
• The sensor requires water flow otherwise oxygen consumption occurs
• Erratic flows can add errors in measurements
• The sensors require frequent calibration
• High upkeep and labour costs

The D-Opto has no compromise with these problems. It enables accuracy, repeatability, reliability, and economy in long term monitoring of dissolved oxygen;

The sensing element in the D-Opto consists of a fluorescing compound suspended stably in a robust optical “window”. A light source at controlled wavelength briefly pulses the optical window. This “excites” the fluorescent material, causing it to emit a specific wavelength of light. The intensity of this fluorescence or light is determined by the amount of dissolved oxygen in the water. That is in contact with the optical window. A highly stable and accurate optical sensor circuit inside the D-Opto measures the emitted fluorescence.

The D-Opto has no consumable components that require replacement

• Unaffected by pollutants and poisons and is highly resilient to bio fouling
• The measurement is not effected by pressure to 100psi
• The D-Opto does not consume oxygen, so no stirring required, and it can even be deployed in stagnate groundwater bores
• The D-Opto uses extremely stable electronics – a calibration interval of 1 year is typical.
• The D-Opto has very low power requirements
• Optical sensors are very robust