1. A method of characterizing the coagulation or sedimentation dynamics of a fluid such as whole blood, a blood fraction, or blood plasma, the method comprising: introducing a sample into a device comprising: a microfluidic device having a microfluidic chamber suitable for receiving a sample of said fluid and enabling it to be illuminated; a lighting means positioned relative to the microfluidic device to illuminate said microfluidic chamber and said sample by a spatially coherent light beam; a two-dimensional matrix image detector configured and arranged relative to the microfluidic device to acquire a time series of two-dimensional images of an optical speckle pattern generated by interaction between said sample and said spatially coherent light beam, wherein said two-dimensional images include pixels; and a non-transient computer readable memory programmed with a computer software, the software configured, with a processor, to obtain a series of two-dimensional images from said two-dimensional matrix image detector, and calculate a function based on a difference between pixels or a correlation of two or more images of the series, and to characterize one or more of the coagulation or sedimentation of said fluid based on said function; illuminating the sample of said fluid with a beam of coherent light; acquiring a time series of two-dimensional images of a speckle pattern generated by interaction between said sample and said spatially coherent light beam, wherein said two-dimensional images include pixels; and processing said time series of two-dimensional images; wherein said processing step includes calculating a function, with the processor, based on a difference between pixels or a correlation of two or more two-dimensional images of the series, and characterizing one or more of the coagulation or sedimentation of said fluid based on said function.