Methods and systems for particle characterisation by imaging free-floating particle movement in liquid enviornment

A method for deriving particle characteristics, the method comprising

• imaging the movement of at least one free-floating particle in a liquid environment at at least one moment in time,
• determining for at least one moment in time at least one movement parameter based on the imaged movement of the free-floating particles in the liquid environment,
• deriving from the at least one movement parameter at least one characteristic of the at least one particle,
• wherein said method comprises:
• imaging the movement of the at least one free-floating particle at at least two moments in time, whereby at least a first imaged movement and a second imaged movement is obtained, and
• determining a change between the first imaged movement and the second imaged movement, and wherein said change is indicative of the movement parameter,
• wherein the change corresponds to at least one of a spatial displacement of the free-floating particle, a velocity associated with the spatial displacement of the free-floating particle, an acceleration associated with the spatial displacement of the free-floating particle, a distribution of the spatial displacement of the free-floating particle, a distribution of the velocity associated with the spatial displacement of the free-floating particle, or a distribution of the acceleration associated with the spatial displacement of the free-floating particle,
• wherein at least one of the spatial displacement, the velocity associated with the spatial displacement, the acceleration associated with the spatial displacement, the distribution of the spatial displacement, the distribution of the velocity associated with the spatial displacement, or the distribution of the acceleration associated with the spatial displacement is determined as a function of time, is subjected to a space-to-frequency conversion is converted into a frequency domain so as to obtain one or more frequencies, and wherein the characteristic of the particle is derived from said one or more frequencies.