BIOLOGICAL-MATERIAL TESTING BY THE PHOTOT HERMAL METHOD - INTEREST INPYROELECTRIC DETECTION

Photothermal methods are well adapted to thin multilayer material anal ysis. In the particular case of biological materials, which are therma lly fragile, low excitation power is required. We have studied whole h uman blood sedimentation by using photothermal radiometry and a photop yroelectric technique. Results obtained with random- and sine-modulate d excitation are discussed. Evolution laws of plasma thicknesses and o ptical absorption coefficients during the process have been determined by identifying the parameters using different estimation methods. It appears that results are consistent with theoretical predictions of ou r 2D-thermophysical model and also with the values measured by the wel l-known Westergreen reference method, usually used in clinical analysi s. Finally, in order to extend the investigation field of the pyroelec tric method, particularly in the domain of biological materials, we ha ve analysed the possibility of using the sensitive pyroelectric sensor s without direct thermal contact with the sample and detecting the tem perature changes at the sample surface through a thin air monolayer.