What they look like

The Dissolved Oxygen Probe is used to measure the concentration of dissolved oxygen in water samples.

Note: The Data Harvest oxygen probe is dual purpose. It can be used to obtain oxygen levels in a gas sample and dissolved oxygen in liquids. Under no circumstances can Vernier or Pasco oxygen gas sensors be used for measuring dissolved gas levels in liquids.

How the sensor work

The Dissolved Oxygen Probe is a Clark-type polarographic electrode that senses the oxygen concentration in water and aqueous solutions. A platinum cathode and a silver/silver chloride reference anode in KCl electrolyte are separated from the sample by a gas-permeable plastic membrane. A fixed voltage is applied to the platinum electrode. As oxygen diffuses through the membrane to the cathode, it is reduced:

The oxidation taking place at the reference electrode (anode) is:

Accordingly, a current will flow that is proportional to the rate of diffusion of oxygen, and in turn to the concentration of dissolved oxygen in the sample. This current is converted to a proportional voltage, which is amplified and read by the interface.

Where it can be used

• Measure oxygen consumption by yeast during respiration
• Investigate how the presence of organic matter affects D.O. levels
• Study biological oxygen demand (B.O.D)
• Ecology studies