Monitoring of liquids rising in porous medium (paper and dental tissue) using full field speckle-correlation technique Maxim Vilensky 1, Natalia A.Trunina 1, Dmitry E. Suetenkov 2, Valery V. Tuchin 1,3,4 1 Saratov State University; 2 Saratov State Medical University; 3 Institute of Precision Mechanics and Control, RAS, Russia; 4 University of Oulu, Finland

Abstract Images sequence of the surface of layers of porous medium (paper and tooth tissues) obtained under coherent irradiation during capillary rise of a liquids were studded. By an analysis of speckle-modulated images of the surface, it is shown that the macroscopic dynamics of the interface at the stage of pinning is mainly controlled by the power law. A phenomenological model was proposed for the macroscopic dynamics of the phase interface for interpreting experimental data. The principal possibility of speckle-correlation technique applying to monitor of liquids diffusion in human tooth dentin was showed. Preliminary results showed that analysis of speckle images obtained at regular intervals over the time allows us to trace the spread of liquids in the interior of the sample, and we have chosen a diagnostic parameter - the average contrast of speckles images in all cases shows saturation, the time which allows us to estimate the diffusion time. A modification of the speckle-correlation technique applied to analysis liquid transfer in heterogeneous non-stationary systems.

test subjects Axio Imager, Carl Zeiss Magnitude 20XMagnitude 100X Dentin tissue

test subjects Magnitude 100XMagnitude 50X Axio Imager, Carl Zeiss filter paper

For diffusion monitoring in this study we used the speckle contrast method, which relates to methods of laser speckle imaging. This simple and highly effective method used, including the visualization of blood flow, was proposed in the mid 90-s of last century and was named LASCA (LAser Speckle Contrast Analysis). LASCA is defining the contrast of time-averaged dynamic speckles depending on the exposure time during the registration of the speckle- modulated images. For processing speckle images and calculation of it contrast in LabVIEW 8.5 (National Instruments, USA) the program was created. This program allow in real-time regime with frame rate up to 100 fps register the intensity distribution of speckle fields and calculate the spatial distribution of the contrast with parallel imaging by the following formula: where N - selected area of speckle image, I – intensity of speckle image, i,j - number of pixel Technique details

Experimental setup Experimental setup. 1 - He-Ne laser with nm wavelength, 2 - microscopic objective, 3, 4 - cuvette with liquid and test sample, 5 - camera objective, 6 - CMOS camera, 7 - PC.

Results a - Speckle-modulated image of the surface of the porous layer during boundary (liquid and gas) development, b - normalized time-correlation functions of speckle image intensity fluctuations at different areas of the image a

Monitoring of speckles contrast changing due to fructose solution 40% penetration in dental tissue

The structural parameters of dentin and paper

Summary The principal possibility of monitoring liquid diffusion in the samples of human tooth dentin and paper was proposed. Preliminary results showed that the analysis of speckle contrast obtained at regular intervals over time allows us to trace the spread of the liquid in the sample, and we had chosen diagnostic parameter - time of contrast speckles changing. In all cases, was showed saturation, and was measured the time of speckle dynamic which allows us to estimate the diffusion time and hence permeability. The proposed technique allows us to study the diffusion of various agents, including drugs, in the dentin and other tissues of the tooth. With the development of a theoretical model should take into account multiple scattering, tubular heterogeneity of dental tissue and using of valid models of penetration an agent through the porous medium

Acknowledgments The research has been made possible by program: FiDiPro TEKES (40111/11) and grants: RFBR # а, #224014; PHOTONICS4LIFE of FP7-ICT ; Projects: #1.4.09, #2.1.1/4989 and # /2950 of RF Ministry of Education and Science; RF Governmental contracts: , 14.B ,