Abstract: An apparatus which enables characterization of particles suspended in a liquid includes a housing with a mixing chamber and a collection chamber separated by a wall containing an aperture for passage of particles between, the mixing chamber and the collection chamber, the mixing chamber further containing a mixing member, a first electrode in the mixing chamber and a second electrode in the collection chamber for conduction of an electrical current through the aperture, a processor that is adapted for controlling the measurement sequence of the apparatus and detecting possible blockage of the aperture by detecting extended duration of the electrical pulse caused by the blocking particle, and upon detection of a blockage, reversing the liquid flow while mixing in the mixing chamber for removal of the blocking particle, and restarting particle counting.

Abstract: A pulse height analyzer for determination of the pulse height distribution of electronic pulses includes a set of comparators with a common input for analogue to digital conversion of the electronic pulses, a set of latches wherein the inputs of the latches are connected to the outputs of respective comparators for recording passage of the corresponding threshold voltages by the rising edge of a pulse, a priority encoder connected to the latch outputs for determination of a pulse height category consisting of pulses with a pulse height within a pulse height interval defined by respective threshold voltages, and a micro controller that is adapted to count the number of pulses within each pulse height category.

Abstract: The present invention relates to a particle characterisation apparatus in which particles suspended in a liquid are passed through an aperture, in principle one by one, to enable characterisation of the particles, for instance by Coulter counting.