Method and system for characterizing the movement speed of particles contained in a liquid, such as blood particles

A method for characterizing a variation in the speed of particles, the particles being contained in a liquid, the liquid including blood

• wherein the method comprises:
• introducing the liquid into a fluid chamber, said fluid chamber having a thickness ranging from 20 μm to 1000 μm;
• lighting the fluid chamber using an excitation light beam emitted by a spatially coherent light source, the light beam extending through the fluid chamber in a longitudinal direction (X);
• acquiring at least two images (In, In+m), respectively at times n and n+m, each image including multiple points (In(x,y), In+m(x,y)), wherein x,y represents the coordinates of each point in the image using a matrix photodetector, the images (In, In+m) being formed by radiation transmitted by the lighted fluid chamber;
• and
• calculating, from said at least two acquired images (In, In+m), a plurality of indicators (Ind1n,n+m) characterizing the variation of the speed of the particles;
• wherein,
• during the acquisition step, the photodetector is positioned at a distance smaller than 1 cm from the fluid chamber in the longitudinal direction, and
• during the calculation step, each calculated indicator is a correlation indicator (Ind1n,n+m) representing a spatial correlation between said two images (In, In+m), so as to characterize the variation of speed of particles, and
• wherein the method further comprises deriving a blood coagulation time from said plurality of correlation indicators (Ind1n,n+m).