Apparatus and method for verifying drop delay in a flow cytometer

• US 6,372,506 B1
• Filed: 07/02/1999
• Issued: 04/16/2002
• Est. Priority Date: 07/02/1999
• Status: Expired due to Term

• Current Assignee: Becton, Dickinson & Co
• Original Assignee: Becton, Dickinson & Co
• Inventors: Norton, Pierce Owen
• Primary Examiner(s): WALLENHORST, MAUREEN
• Application Number:
  US09/346,692
• Time in Patent Office: 1,019 Days
• Field of Search: 436/63, 436/164, 422/73, 422/82.05, 250/461.2, 209/3.1, 209/3.2, 209/3.3, 209/4, 209/552, 209/571, 209/576-579, 209/127.4, 209/906
• US Class Current: 436/63
• CPC Class Codes: G01N 15/1404 Handling flow, e.g. hydrodynamic focusing
• CPC Class Codes: G01N 15/149 specially adapted for sorting particles, e.g. by their size or optical properties
• CPC Class Codes: G01N 15/1492 within droplets
• CPC Class Codes: G01N 2015/1406 Control of droplet point
• CPC Class Codes: G01N 2015/1481 Optical analysis of particles within droplets sorting particles within droplets G01N15/1492
• CPC Class Codes: Y10S 209/906 Pneumatic or liquid stream feeding item

Abstract

An apparatus and method for verifying the drop delay in a flow cytometer, which is indicative of the time that elapses from a moment at which a particle of interest is detected at an interrogation point in the flow of cytometer to the moment at which a sorting condition, such as a charging potential, is applied in response to the detection to a droplet forming at a droplet forming location in the flow cytometer. The apparatus and method analyzes the content of the droplets formed by the flow cytometer, and based on the analysis, provides an indication as to whether the drop delay time at which the flow cytometer is operating is correct. Specifically, the charging potential should be applied to the droplet containing the detected particle of interest. The content of the droplets can be analyzed at the droplet formation point, or at a location downstream of the droplet formation point, to detect the presence or absence of a particle of interest that was detected at the interrogation point in the flow cytometer. The drop delay time at which the droplets being formed by the flow cytometer are charged can then be set based on the results of the analysis of the content of the droplets, to ensure that droplets containing particles of interest are charged and thus sorted by the flow cytometer, while droplets not including particles of interest remain uncharged and are not sorted.

Claims

1. An apparatus, for use in a flow cytometer, for verifying accuracy of a drop delay setting representing a period of time elapsing between a moment at which any of a plurality of particles in a fluid flowing through said flow cytometer is detected at a reference location and a moment at which a sorting condition is applied in response to said detection of a droplet of said fluid forming at a droplet forming location, said apparatus comprising:

a first detector, adapted to detect a presence of at least one of said particles at said reference location; and

a second detector, adapted to detect a presence or absence of said at least one of said particles within at least one intact droplet either at formation or in freefall at a droplet detection location downstream of said reference location to provide an indication of the accuracy of said drop delay.

2. An apparatus as claimed in claim 1, wherein:

said droplet detection location is at a distance downstream of said droplet forming location.

3. An apparatus as claimed in claim 1, wherein:

said droplet detection location is downstream of a location in said flow cytometer in which said droplets are sorted.

4. An apparatus as claimed in claim 1, further comprising:

a controller which controls applying said sorting condition to said droplet at said droplet forming location based on said presence or absence of said at least one of said particles within said droplet detected by said second detector, said sorting condition including applying a charging potential to said droplet.

5. An apparatus as claimed in claim 4, wherein:

said controller automatically controls applying said charge to said droplet at said droplet forming location.

6. An apparatus as claimed in claim 1, wherein:

said second detector detects a presence or absence of said at least one of said particles within each of a plurality of droplets at said droplet detection location.

7. An apparatus as claimed in claim 1, wherein said second detector is adapted to the detect a presence or absence of said at least one of said particles within at least one intact droplet while said droplet is in freefall.

8. An apparatus as claimed in claim 1, wherein said second detector is adapted to detect the presence of said at least one of said particles within at least one intact droplet.

9. An apparatus as claimed in claim 1, wherein said second detector is adapted to detect the absence of said at least one of said particles within at least one intact droplet.

10. An apparatus, for use in a flow cytometer, for verifying accuracy of a drop delay setting representing a period of time elapsing between a moment at which any of a plurality of particles in a fluid flowing through said flow cytometer is detected at a reference location and a moment at which a sorting condition is applied in response to said detection of a droplet of said fluid forming at a droplet forming location, said apparatus comprising:

a first detector, adapted to detect a presence of at least one of said particles at said reference location; and

a second detector, adapted to detect a presence or absence of said at least one of said particles within at least one intact droplet at a droplet detection location downstream of said reference location to provide an indication of the accuracy of said drop delay;

wherein said droplet detection location substantially corresponds to said droplet forming location.

11. A method for verifying accuracy of a drop delay setting in a flow cytometer, said drop delay representing a period of time elapsing between a moment at which any of a plurality of particles in a fluid flowing through said flow cytometer is detected at a reference location to a moment at which a sorting condition is applied in response to said detection of a droplet of said fluid forming at a droplet forming location, said method comprising the steps of:

detecting a presence of at least one of said particles at said reference location; and

detecting a presence or absence of said at least one of said particles within at least one intact droplet during formation or in freefall at a droplet detection location downstream of said reference location to provide an indication of the accuracy of said drop delay.

12. A method as claimed in claim 11, wherein:

said droplet detection location is at a distance downstream of said droplet forming location.

13. A method as claimed in claim 11, wherein:

said droplet detection location is downstream of a location in said flow cytometer in which said droplets are sorted.

14. A method as claimed in claim 13, wherein:

said droplet presence or absence detection step detects said presence or absence of said at least one of said particles within said droplet which has been sorted by said flow cytometer.

15. A method as claimed in claim 11, wherein:

said droplet presence or absence detection step detects said presence or absence of said at least one of said particles within said droplet which is an unsorted droplet.

16. A method as claimed in claim 11, further comprising the step of:

controlling application of said sorting condition to said droplet at said droplet forming location based on said detected presence or absence of said at least one of said particles within said intact droplet, said sorting condition including applying a charging potential to said droplet.

17. A method as claimed in claim 16, wherein:

said controlling step automatically controls said charging of said droplet at said droplet forming location.

18. A method is claimed in claim 11, wherein:

said presence or absence detecting step detects a content of each of a plurality of droplets at said droplet detection location.

19. A method as claimed in claim 11, wherein said step of detecting the presence or absence of said at least one of said particles within said at least one intact droplet occurs while said droplet is in freefall.

20. A method as claimed in claim 11, wherein said step of detecting the presence or absence of said at least one of said particles within said at least one intact droplet detects the presence of said particles.

21. A method as claimed in claim 11, wherein said step of detecting the presence or absence of said at least one of said particles within said at least one intact droplet detects the absence of said particles.

22. A method for verifying accuracy of a drop delay setting in a flow cytometer, said drop delay representing a period of time elapsing between a moment at which any of a plurality of particles in a fluid flowing through said flow cytometer is detected at a reference location to a moment at which a sorting condition is applied in response to said detection of a droplet of said fluid forming at a droplet forming location, said method comprising the steps of:

detecting a presence of at least one of said particles at said reference location; and

detecting a presence or absence of said at least one of said particles within at least one intact droplet at a droplet detection location downstream of said reference location to provide an indication of the accuracy of said drop delay

wherein said droplet detection location substantially corresponds to said droplet forming location.