Method for determining the presence or absence of disposable pipette tips in pipette tip carriers

Patent metadata

Field	Value
Publication number	US-10168346-B2
Application number	US-201515310269-A
Country	US
Kind code	B2
Filing date	Apr 17, 2015
Priority date	May 15, 2014
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

A method for determining the presence or absence of disposable pipette tips in pipette tip carriers on the work area of a laboratory workstation. Each of the pipette tip carriers has a support panel with receiving holes into each of which a disposable pipette tip can be inserted. The laboratory workstation for carrying out the method has a robot arm with at least one pipette which is designed to receive and dispose of disposable pipette tips. The laboratory workstation has a digital camera which is arranged on a support device and is operatively connected to an analyzing unit. The work area of the laboratory workstation can be completely imaged in at least one first direction using the digital camera.

First claim

The invention claimed is:

1. A method for determining presence or absence of disposable pipette tips ( 1 ) in selected pipette tip carriers ( 2 ) on the work area ( 3 ) of a laboratory work station ( 4 ), wherein each of the selected pipette tip carriers ( 2 ) comprises a carrier plate ( 5 ) with an orthogonal arrangement of receiving holes ( 6 ), in which respectively one disposable pipette tip ( 1 ) can be inserted, wherein the laboratory work station ( 4 ) comprises a robot arm ( 7 ) with at least one pipette ( 8 ), which is configured for receiving and delivering liquid samples and for receiving and discarding disposable pipette tips ( 1 ), and wherein the laboratory work station ( 4 ) comprises a digital camera ( 9 ) which is disposed on a carrier device ( 10 ) and which is operatively connected to an evaluation unit ( 11 ), and with which the work area ( 3 ) of the laboratory work station ( 4 ) can be completely imaged at least in a first direction, wherein by using the evaluation unit ( 11 ):
a) the pipette tip carriers ( 2 ) arranged on the work area ( 3 ) of the laboratory work station ( 4 ) are selected;
b) at least one digital image ( 12 ) with a plurality of pixels is taken of each of the selected pipette tip carriers ( 2 ) using the digital camera ( 9 );
c) in relation to the at least one digital image ( 12 ) of each of the selected pipette tip carriers ( 2 ), a grid ( 14 ) consisting of grid elements ( 13 ) is defined on the respective pipette tip carrier ( 2 ), wherein the grid ( 14 ) is spanned by the four outermost receiving holes ( 6 ′) of an arrangement of receiving holes; characterized in that the grid ( 14 ) is an orthogonal grid with square grid elements ( 13 ) adapted perspectively to the at least one digital image ( 12 ), wherein:
d) in relation to the at least one digital image ( 12 ) of each of the selected pipette tip carriers ( 2 ), pixel areas ( 15 ) which can be assigned to the grid elements ( 13 ) are determined, whereby each of the grid elements ( 13 ) of the grid ( 14 ) is divided into four quadrants ( 18 );
e) in each of the determined pixel areas ( 15 ) of the at least one digital image ( 12 ) a respective number of pixels whose brightness lies in a predetermined range is determined; and
f) determining whether the disposable pipette tip ( 1 ) is present or absent in one of the receiving holes ( 6 ) of the selected pipette tip carriers ( 2 ) when the number of pixels determined in step e) lies in the predetermined range relative to a predetermined threshold value.

2. The method according to claim 1 , characterized in that two digital images ( 12 ) of each of the selected pipette tip carriers ( 2 ) with a plurality of pixels are recorded with the digital camera ( 9 ), wherein:
i) a first digital image serves as reference image and is used to determine actual positions of the four outermost receiving holes ( 6 ′) as well as threshold values for low-brightness pixels; and
ii) a second digital image serves as run-time image and is used to determine which of the receiving holes ( 6 ) are occupied by the disposable pipette tips ( 1 ).

3. The method according to claim 1 , characterized in that the digital camera ( 9 ) has an optical axis ( 16 ), which passes through the carrier plate ( 5 ) of the selected pipette tip carriers ( 2 ) disposed on the work area ( 3 ) of the laboratory work station ( 4 ) at a first angle, wherein the first angle is in a range of 40° to 90° and especially preferably is 68°.

4. The method according to claim 1 , characterized in that the grid ( 14 ) with its grid lines ( 17 ) is defined on the selected pipette tip carriers ( 2 ) such that:
(i) points of intersection of the grid lines ( 17 ) lie at the centre of the receiving holes ( 6 ); or
(ii) the receiving holes ( 6 ) are framed by the grid lines ( 17 ).

5. The method according to claim 1 , characterized in that one of the quadrants ( 18 ) of each of the grid elements ( 13 ) is defined as the determined pixel areas ( 15 ).

6. The method according to claim 1 , characterized in that one of the grid lines ( 17 ) of each of the grid elements ( 13 ) adjoining one of the quadrants ( 18 ) is determined as the determined pixel areas ( 15 ) respectively.

7. The method according to claim 1 , characterized in that the determined pixel areas ( 15 ) are determined in each of the grid elements ( 13 ) of the grid ( 14 ) by means of a mask.

8. The method according to claim 1 , characterized in that the determined pixel areas ( 15 ) are defined at least approximately as a cut set of one of the four quadrants ( 18 ) with a circle of the receiving holes ( 6 ) of the selected pipette tip carriers ( 2 ).

9. The method according to claim 1 , characterized in that in each of the determined pixel areas ( 15 ) of the at least one digital image ( 12 ) a number of all low-brightness pixels is determined, and that the presence of the a disposable pipette tips ( 1 ) in the receiving holes ( 6 ) of the selected pipette tip carriers ( 2 ) is determined, if the number of pixels determined in step e) is the same as or higher than a respectively predetermined threshold value.

10. The method according to claim 1 , characterized in that in each of the determined pixel areas ( 15 ) of the at least one digital image ( 12 ) a number of all low-brightness pixels is determined, and that the absence of the disposable pipette tips ( 1 ) in the receiving holes ( 6 ) of the selected pipette tip carriers ( 2 ) is determined if the number of pixels determined in step e) is less than a respectively predetermined threshold value.

11. The method according to claim 9 , characterized in that the number of all low-brightness pixels of the pixel areas ( 15 ) of the at least one digital image ( 12 ) is determined.

12. The method according to claim 1 , characterized in that the robot arm ( 7 ) of the laboratory work station ( 4 ) is simultaneously configured as the carrier device ( 10 ) for the digital camera ( 9 ).

13. The method according to claim 1 , characterized in that the work area ( 3 ) of the laboratory work station ( 4 ) forms a horizontal plane which is spanned between the X and Y axes of a Cartesian coordinate system.

14. The method according to claim 13 , characterized in that the robot arm ( 7 ) of the laboratory work station ( 4 ) is moved in the direction of the X axis and/or the Y axis for recording the at least one digital image ( 12 ) with the digital camera ( 9 ).

15. The method according to claim 14 , characterized in that the robot arm ( 7 ) of the laboratory work station ( 4 ) is moved into a X position in relation to the selected pipette tip carriers ( 2 ) for recording the digital images ( 12 ) with the digital camera ( 9 ).

16. The method according to claim 13 , characterized in that the digital camera ( 9 ) has a field of view which in the Y direction of the Cartesian coordinate system deviates by at least a second angle, preferably by a third angle and in the X direction of the Cartesian coordinate system deviates by at least a fourth angle.

17. The method according to claim 16 , characterized in that the digital camera ( 9 ) has the field of view in which the second angle is 14°, the third angle is 24°, and the angle is 18°.

18. The method according to claim 12 , characterized in that the robot arm ( 7 ) with the digital camera ( 9 ) fastened thereon is positioned such that all of the selected pipette tip carriers ( 2 ) of a carrier ( 20 ) set up in the work area ( 3 ) of the laboratory work station ( 4 ) are in view of the digital camera ( 9 ) for three pipette tip carriers ( 2 ).

Assignees

• Tecan Trading Ag
• Halg Werner

Inventors

• Schmidt Martin
• Kerkmann Rainer

Classifications

• G06T7/0008

  checking presence/absence · CPC title

• G01N35/1011 Primary

  Control of the position or alignment of the transfer device · CPC title

• G01N35/04

  Details of the conveyor system {(G01N35/021 - G01N35/028 take precedence)} · CPC title

• G06T2207/30164

  Workpiece; Machine component · CPC title

• G01N2035/0493

  Locating samples; identifying different tube sizes · CPC title