Photoacoustic detection of drug diffusion into a membrane: Theory and numerical analysis

Possibility of the analysis of drug penetration through membranes using photoacoustic effect is considered. Based on Fick's second law the problem of the spatial and time dependent distribution of drugs in membranes is solved. The solution allows to derive the distribution of heat sources arising in the membrane from intensity modulated light illumination. Subsequently the temperature of the illuminated membrane surface is analysed numerically. This temperature is directly correlated to the signal registered in photoacoustic measurements. The influence of different parameters of the theoretical model on the ac component of the temperature of illuminated membrane surface has been analysed. Conclusions about possibilities and limitations of the considered method are discussed.