Sample dilution module with offset mixing chamber

摘要

The sample dilution module includes an oil filled aspiration probe and mixing chamber that communicate with each other while the mixing chamber is maintained at an angle of approximately 5 to 45 degrees below a horizontal axis. The aspiration probe is maintained in a vertical orientation. A micro-bubble is aspirated between separate aspirations of test sample and diluent to prevent contact between the sample and diluent in the aspiration probe. The test sample and diluent are then drawn from the vertically oriented aspiration probe into the mixing chamber. After the sample and diluent are in the mixing chamber the micro-bubble of air can migrate away from the test sample and diluent to enable the test sample and diluent to contact each other. Mixing of the test sample and diluent is accomplished by moving the test sample and diluent back and forth in the mixing chamber without physical agitation of the mixing chamber and without any mixing element in the mixing chamber. Such movement is accomplished by alternate suction and vacuum forces imposed on the fluid in the mixing chamber.