AMT - Laboratory Oxygen Micro-Sensor

Because of the partial pressure of gaseous O2 dissolved in the sample the analyte is separated by permeation through the membrane. The membrane is only pervious to gases, so that liquids, ions and solids are not able to reach the inner electrolyte of the sensor. Inside the sensor contains a buffered solution and 3 electrodes. The electrode materials are selected carefully to realize a self polarization for requested electrochemical reduction of oxygen at the working electrode surface. Therefore essential shorter times for putting into operation after switching on are observed compared with the normally delivered amperometric sensors. If the O2 passes now the membrane, the oxygen is transported by diffusion to the working electrode followed by the electrochemically reduction of the  O2. This causes a current depending on the oxygen partial pressure/oxygen concentration of the analyte. The observed very small current within a range of some hundred picoamperes is converted into a voltage of 0...5 Volt (main working range: 0...1,500 mV) inside the integrated electronic device of the sensor. Besides, the current flow in the galvanic sensor leads to a rapid decrease of the analyte inside the sensor resulting in very fast response times. This is also observed, if a rapid change from high to very low concentration levels is necessary.

All electrochemically working oxygen sensors have to be combined with a temperature sensor. When ordering a complete AMT submersible probe system, the temperature measurement and the temperature correction of the sensor signal is already included. If measurements in a flow through system are required, special temperature sensors for the integration in AMT flow through cells are offered. When measuring in opened vessels or beakers in the laboratory, the customers have to realize the temperature measurement themselves. If a sensor with temperature compensation data is ordered, the temperature correction of the signal is very easy by means of a factor or for more accurate measurements by means of a mathematical formula.