Thermal Biosensors in Biotechnology - Advances in Biochemical Engineering Biotechnology - page 38

Fig.2. Four channel ET for on-line bioprocess control
were fixed at the cartridge inlet and outlet. The difference method enables a
finer measurement.The design allows a fast interchange of exhausted enzymes.
A 22-bit A/D board completely covers the range of the wheatstone bridges.
Therefore,manual equalizing is not necessary.Additionaly,the system allows us
to acquire up to eight different sensor signals (e.g.,pO 2 - or pCO 2 data),and con-
trols up to twelve valves or pumps.
The multi channel ET sucessfully managed a fully automated bioprocess
monitoring and control.Hundeck et al.(1992) used it in several bioprocesses for
monitoring different sugars simultaneously (glucose,maltose,sucrose and lac-
tose).Moreover,the system was used for enantioselective monitoring of amino-
acid esters, and detailed investigations were performed with immobilized
microorganisms.Nevertheless,the system is very unwieldy,the operation soft-
ware too complicated and the electronic modules outdated.
In the last five years,hardware development has been focused more on minia-
turization and new sensor concepts.Due to customers requirements,a need for
simpler operation was realized as well.
3
Applications of Enzyme Thermistors - A Review
On the basis of a universal detection principle,the ET has attracted wide atten-
tion for several analytical procedures. In this section, applications are pointed
out that have been of great interest in the last decade and explains ETs'attrac-
tion in bioanalytical sciences.