This special volume on "bioanalysis and biosensors for bioprocess monitoring" has a twofold target. Firstly, it is dedicated to the 75th birthday ofArmin Fiechter, who was a major driving force among the pioneers to the progress of biochemical engineering. Not only the aseptic connection technique with septa and needles still used until today was established by him, but also the development of the first sterilizable pH electrodes with W Ingold is also credited to him. He made in vivo bio analysis a topic of general interest, for instance by setting up the first chemostat in Switzerland. It was again Armin Fiechter who pushed the use of non invasive exhaust gas analysis