In recent years, cancer has been one of the major causes of death. Undoubtedly, the detection and identification of possibly malignant cells in early stages is vital.
Infrared (IR) spectroscopy which is based on the absorption of IR light due to molecular vibrations has proven to be able to distinguish mammalian tumour cells from healthy cells. But instead of recording the whole spectrum with a commercial IR spectrometer a distinction can also be achieved by comparing the absorbance of cell samples at only a few specific wavelengths that are characteristic for certain molecules in the cell membrane.
In this thesis the design and operation of a cost-effective sensor system for IR absorbance measurements at six wavelengths in the 3.3 - 3.7 m range is described. The sensor setup consists of IR-LEDs (light emitting diodes), a photodiode detector, and optical components.
CH2 and CH3 of acyl chains in the cell membrane show distinct absorbance peaks at specific wavelengths (symmetric and antisymmetric stretch vibrations). Cell membrane alterations associated with tumour formation result in an absorbance change in the CH2-stretch ratio that can be detected with the sensor system and used for cell type discrimination.
IR absorbance measurements were performed on epithelial kidney cell lines (normal MDCK (Madine Darby Canine Kidney) and malignant Caki-1) and melanoma cell lines (M14, A375, and 518A2). Cell samples were measured dried and suspended in PBS (phosphate buffered saline). Hence, a microfluidic chip made of IR transparent calciumflouride comprising a microchamber for cell suspension liquid was developed and realised. Chip design and fabrication steps are presented in this thesis.
Measurement results show that a clear and reproducible discrimination between healthy and malignant epithelial kidney cells as well as between the three different melanoma cell lines can be achieved by comparing the CH2- and CH3-stretches.