Apparatus and method for forming a membrane

A method for forming a membrane on an immersion tube for an electrochemical sensor, comprising steps as follows:

• providing a first immersion tube having a first opening and a second opening, as well as an apparatus having a melting system, a positioning system, an imaging apparatus, a pressure supplier, and a control system,
• wherein the melting system includes a heater and a crucible containing a melt,
• wherein the positioning system is suitable to move the first immersion tube relative to the crucible, such that the first opening of the first immersion tube is immersed in the melt,
• wherein the imaging apparatus includes a first camera, which is temperature sensitive and is arranged in such a manner that it can see the melt,
• wherein the pressure supplier is connected air tightly with the first opening of the first immersion tube,
• wherein the control system is connected with the melting system, the positioning system, the imaging apparatus and the pressure supplier,
• heating the melt with the heater to a predetermined first temperature,
• evaluating a surface of the melt by the first camera, such that at least a first region with
• a first measured temperature and a second region with a second measured temperature are identified, wherein the first measured temperature is less than the second measured temperature,
• immersing the second opening of the first immersion tube in the first region of the surface of the melt,
• withdrawing the first immersion tube from the melt while supplying a first pressure by means of the pressure supplier, such that a membrane forms over the second opening of the first immersion tube.