Depth-resolved analysis of biofilms by photoacoustic spectroscopy

A photoacoustic sensor system is presented for depth-resolved analysis of b iofilms. The investigation of biofilm growth on the surface of the sensor h ead showed the potential of Photoacoustic Spectroscopy (PAS) in this area. The increase of biomass was monitored by analysis of the photoacoustic sign al amplitudes (wavelength lambda = 550 nm). The distribution of the organic mass inside the biofilm was derived from absorption profiles, which were c alculated from the measured pressure profiles. Wavelength-dependent measure ments allowed the determination of absorption spectra. In this way, changes in the composition of the biofilm could be monitored. Measurements with se veral sensor heads in combination with an optical fiber multiplexer may all ow the determination of three-dimensional profiles of biofilms. A new photo acoustic sensor system was set up, which permits the observation of a biofi lm at 3 positions in a biofilm reactor.