Patent ID: 8202733

Claim:
A method for hydrodynamic focusing of a first fluid within a second fluid in a flow cytometer, the method comprising the steps of: pressurizing the first fluid and the second fluid at a pre-defined pressure, the first fluid and the second fluid being pressurized using a pressure source; controlling a first flow rate corresponding to the first fluid, the first flow rate being controlled by flow resistance of a first flow circuit downstream of the pressure source; controlling a second flow rate corresponding to the second fluid, wherein the second flow rate is controlled by flow resistance of a second flow circuit downstream of the pressure source; and passing the first fluid and the second fluid through a converging section, wherein the first fluid is hydrodynamically focused in the converging section; and altering at least one of the first and second flow rates by reconfiguring the corresponding flow resistance of at least one of the first and second flow circuits; wherein the pre-defined pressure is non-independently applied against both the first and second fluids upstream from the first and second flow circuits while altering at least one of the first and second flow rates.