What is the function of the MLT1122 Oxygen Analog Adapter?

The MLT1122 Oxygen Analog Adapter (O2-ADPT ) is required to interface the following O2 probes with a PowerLab:

The MLT1122 functions both as an electrometer and a pre-amplifier. The electrometer, by way of its extremely high impedance, effectively converts the low current produced by the probe to a voltage only signal that can be read by a PowerLab.

Note that the MLT1122 has 2 CR2032 batteries that convert the current to a voltage and provide the polarization voltage to power the electrodes to drive the reaction. As a result, the MLT1120 O2 probe needs to be isolated from other measurements (e.g., pH and redox) to avoid ground loops.

One of the main reasons for using micro probes such as the MLT1122  is that the consume very little oxygen and can be used to measure oxygen in stagnant or other non-stirred solutions.

Note that the MLT1120 and MLT1123 are polarographic electrodes as oppossed to galvanic types (such as the MLT1115 Galvanic Oxygen Electrode) which do not require an external voltage.