Patent ID: 7874718

Claim:
An apparatus for mixing a first liquid with a second liquid, the apparatus comprising: a pumping assembly having a first pump chamber in valved fluid communication through a channel with a second pump chamber, each pump chamber having a variable volume, the volume depending on the position of a barrier separating the pump chamber from a positive or negative pressure source, the pump chamber being capable of pumping liquid under the influence of the pressure source acting on the barrier; a first pressure transducer to measure the pressure associated with the first pump chamber, and a second pressure transducer to measure the pressure associated with the second pump chamber; a first pump controller operatively coupled to the pumping assembly to control the pumping of a first liquid into the first pump chamber through a first inlet of the pumping assembly; and a second pump controller operatively coupled to the pumping assembly to control the pumping of a quantity of a second liquid into the second pump chamber through a second inlet of the pumping assembly, and into one of the channel and the first pump chamber so as to mix the first liquid and the second liquid within the pumping assembly, wherein the first and second pump controllers can control pumping at least in part by being configured to receive pressure information from the first and second pressure transducers, and to use the pressure information to determine the volume of liquid pumped through the first pump chamber and the second pump chamber.