Control of flow cytometer having vacuum fluidics

• US 5,395,588 A
• Filed: 02/19/1993
• Issued: 03/07/1995
• Est. Priority Date: 12/14/1992
• Status: Expired due to Term

• Current Assignee: Becton, Dickinson & Co
• Original Assignee: Becton, Dickinson & Co
• Inventors: North, Howard Jr., Uffenheimer, Kenneth F.
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): Ludlow, Jan M.
• Application Number:
  US08/019,716
• Time in Patent Office: 746 Days
• Field of Search: 422/68.1, 422/81, 422/63, 422/67, 73/864.83, 436/63
• US Class Current: 422/81
• CPC Class Codes: G01N 15/1404 Handling flow, e.g. hydrodynamic focusing

Abstract

The present invention relates to a system for controlling the movement or transport of objects such as cells and other particles in a moving liquid stream. More particularly the invention relates to a system including a vacuum pump which pulls the sheath fluid from an open supply reservoir through a flow cell assembly where cell analysis occurs and discharges the flow cell effluent to an open waste reservoir. A pressure drop is created through the conduit leading from the supply reservoir to the flow cell which aspirates the cell suspension from an open sample vessel into and through the flow cell. The vacuum is regulated by controlling the electric power applied to the vacuum pump motor. Starting, stopping, reverse flushing, and draining of the flow cell assembly are controlled by programming the operation of four electric solenoid valves in fluid communication with the flow cell inlet and outlet passages, the operation of a reverse flush pump and, the operation of an electrically controlled tube lifter. A deaerator is provided to remove some of the air dissolved in the sheath fluid provided to the flow cell assembly to prevent the release of air and formation of adherent air bubbles in sensitive areas of the flow cell assembly.

Claims

1. A flow cytometer control system for controlling the delivery of a cell sample drawn from a vessel, comprising:

a flow cell, in communication with a cell sample vessel, for performing cell sample analysis;

an intake passage, connected to said flow cell, providing an ingress communication path for sheath fluid into said flow cell;

first outlet passage, connected to said flow cell, providing a first egress communication path for said sheath fluid out of said flow cell;

a vacuum pump with motor means, in vacuum communication with said first outlet passage and a second outlet passage, for pulling said sheath fluid through said flow cell;

flow resistor means, connected to said intake passage, for developing a pressure drop along said intake passage to cause cell sample to be aspirated from said vessel into said flow cell;

a first valve, connected to said intake passage, for controlling the flow of said sheath fluid into said flow cell at a predetermined cell sample flow rate;

a second valve, connected to said first outlet passage, for controlling the flow of said sheath fluid out of said flow cell;

control means for opening said second valve for a predetermined time prior to opening said first valve in order to permit a vacuum to be developed in said flow cell before opening said first valve thereby pulling cell sample through said flow cell to increase sample flow into said analysis region; and

said control means being operatively connected to said first and second valves.

2. The control system of claim 1, further comprising:

processor means, connected to said first and second valves, for controlling the actuation of said first and second valves under programmed control.

3. The control system of claim 1 further comprising:

a sensor, connected to said first outlet passage, for sensing the vacuum level of said sheath fluid;

driver means, coupled to said vacuum pump motor, for regulation of power delivery to said vacuum pump motor; and

controller means, coupled to said sensor and said driver means, for controlling the operation of said driver based on said vacuum level;

whereby power delivery to said vacuum pump motor may be modulated based on said vacuum level to adjust said vacuum level to a predetermined fixed value.

4. The control system of claim 1, further comprising:

a supply reservoir connected to said first intake passage; and

a waste reservoir connected to said first and second outlet passages.

5. The control system of claim 1, wherein said first and second valves are solenoid actuated.

6. The control system of claim 1, further comprising:

a sensor, connected to said first outlet passage, for sensing the vacuum level of said sheath fluid;

a driver, coupled to said vacuum pump motor, for regulation of power delivery to said vacuum pump motor; and

controller means, coupled to said sensor and said driver, for controlling the operation of said driver based on said vacuum level;

whereby power delivery to said vacuum pump motor is modulated based on said vacuum level thereby adjusting said vacuum level to a predetermined fixed value.

7. The control system of claim 1, further comprising:

a sample uptake tube, connected to said flow cell, for providing a communication path into said flow cell; and

a tube lifter, movably positioned a predetermined distance from said uptake tube, for moving said cell sample vessel to position said sample uptake tube inside said cell sample vessel, with the rate of descent of said tube lifter being controlled by a processor means;

whereby any external residue in said sample uptake tube is allowed to drain into said cell sample vessel to reduce carryover of cell sample between test cycles.

8. The control system of claim 7, further comprising:

a third valve, connected to said first outlet passage and to the atmosphere, for providing a communication path to atmospheric pressure at such time that said tube lifter is descending to substantially eliminate the vacuum developed in said flow cell thereby preventing air from being drawn into said flow cell with no sample being present.

9. The control system of claim 1, further comprising:

a deaerator, connected to said intake passage, for removing gas dissolved in said sheath fluid.

10. The control system of claim 9, wherein sad deaerator is made of a material which is permeable to oxygen and nitrogen to allow these gases to diffuse through its wall when subjected to a vacuum.

11. The control system of claim 10, wherein said deaerator includes at least one length of tubing, and said tubing is contained within a jar which is subjected to said vacuum thereby serving to dampen the vacuum pulsations of said vacuum.