During dialysis the patient's blood is cleaned (or purified) using an artificial kidney.
This medical device should be fitted with various safety accessories because it works with an essential part of the human body and blood comes into contact with it. The blood leak detector is one example of these safety devices, its purpose is to prevent patients from bleeding to death when the dialysis machine malfunctions. If the machine does not indicate the leaking of blood in time, the consequences can be fatal due to severe blood loss. Therefore it is important that even small blood leaks are detected as reliably as possible. The thesis explores the blood leak detectors currently in use and the physical background in relations to the method of measurement. The spectral transmission of blood was tested accordingly, and based on the results a new circuit was designed. We can measure much more precise with this new circuit. Comparative measurements were carried out at the end of the dissertation, which showed the expected results.