Entwicklung eines Pulsoxymeters zur Bestimmung der Sauerstoffsättigung und der Herzrate von sedierten Labormäusen

This master's thesis deals with the development of a pulse oximeter for use in sedated laboratory mice to determine the vital signs oxygen saturation and heart rate in order to allow continuous monitoring. To achieve that, a measuring hardware with the appropriate analysis software in a micro-controller has to be designed, which calculates these parameters, displays them on an LCD and supplies the digital data via a USB connection to a MATLAB GUI.\vspace{-4mm}

Methods:
Through the use of a modified pulse oximeter sensor, the different absorption of oxihemoglobin and desoxihemoglobin at two different wavelengths in the arterial blood can be measured and used to calculate the functional oxygen saturation. For this purpose a micro-controller controls the LED currents of the transmitting diodes and the signal isolation, as well as the analog signal amplification and digitalizes the pulse wave signals at two different wavelengths.

Results:
After a pre-processing, the amplitudes of the digital pulse wave are extracted, the heart rate and the oxygen saturation are calculated and displayed on an LCD. The digital signals that are present in the microprocessor memory data can be transferred via a USB connection to a PC with MATLAB GUI in order to process and analyze them graphically.

Conclusion:
With the developed hardware it is possible to measure the heart rate and the oxygen saturation of a sedated mouse and display them clearly on an LCD. In order to verify the accuracy of these values a calibration with subsequent validation is needed. However, this has not been done in this study.