Reagent addition system and method

Abstract

A system and method for transferring micro-amounts of liquids at accurately controlled rates and volume through the use of independent precision rotary and linear motion mechanisms. The system generally includes a pump module, an indexing module for incrementally translating at least one nozzle mounted thereto and a programmable controller for controlling the pump module and the indexing module. The pump module generally includes a chambered block, a piston drive assembly having a piston, a first motor mechanically coupled to the piston drive assembly for rotating the piston and a second motor mechanically coupled to the piston drive assembly for axially translating the piston. The chambered block has a liquid chamber, an inlet port in fluid communication with the liquid chamber and a discharge port in fluid communication with the liquid chamber. The inlet port of the chambered block is radially spaced from the discharge port. The piston is rotatably and translationally supported in the liquid chamber of the chambered block and includes a relieved portion. The first motor rotates the piston between a first position wherein the relieved portion of the piston is aligned with the inlet port of the chambered block and a second position wherein the relieved portion of the piston is aligned with the discharge port of the chambered block. The second motor axially translates the piston within the liquid chamber of the chambered block independent of the first motor to alternately draw in and discharge liquid to and from the liquid chamber.