Apparatus and method for determining the mechanical properties of cells

Patent metadata

Field	Value
Publication number	US-2016202172-A1
Application number	US-201414913699-A
Country	US
Kind code	A1
Filing date	Jun 26, 2014
Priority date	Aug 23, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

The present invention relates to a method and an apparatus for sorting cells. The apparatus for determining the mechanical properties of cells comprises: —a microfluidic channel having an inlet and an outlet, the channel being configured to let a fluid containing cells pass therethrough, —a means for introducing a fluid containing cells into the channel so as to establish a flow of the fluid within the channel, —a cell shape measurement device arranged to obtain information of a deformed shape of a cell deformed due to the flow pattern created by the interaction of the fluid flow with the channel, and —an analysis means arranged to use data from the cell shape measurement device to obtain mechanical properties of the cells.

First claim

1 . Apparatus for determining the mechanical properties of cells, comprising:
a microfluidic channel ( 10 ) having an inlet and an outlet, the channel being configured to let a fluid containing cells pass therethrough, a means ( 30 ) for introducing a fluid containing cells into the channel ( 10 ) so as to establish a flow of the fluid within the channel ( 10 ), a cell shape measurement device ( 20 , 22 ) arranged to obtain information of a shape of a cell deformed due to the flow pattern created by the interaction of the fluid flow with the channel ( 10 ), and an analysis means ( 60 ) arranged to use data from the cell shape measurement device ( 20 , 22 ) to obtain mechanical properties of the cells, wherein the cell shape measurement device ( 20 , 22 ) comprises an optical device arranged to obtain an optical information regarding a shape of the cell as it travels through the channel, the optical device being an image acquisition device ( 20 , 22 ) arranged so as to image cells as they pass through the channel, the image acquisition device ( 20 , 22 ) being arranged to obtain an image of a region of interest within the channel ( 10 ) such that cells present within the region of interest are imaged, wherein the analysis means ( 60 ) is arranged to carry out the following steps: b) determining an estimate of a cell contour by only considering those pixels as forming part of the estimate of the cell contour which have a value corresponding to a predefined change in the brightness value in the image obtained when a cell is passing through the region of interest, when compared with the average image obtained as an average of several images obtained of the region of interest, and, subsequently, c) determining from the estimate of the cell contour the deformation of the cell contour due to the flow within the channel.

2 . Apparatus according to claim 1 , the apparatus being arranged to determine the mechanical properties of the cells as they pass through the channel.

3 . Apparatus according to one of claims 1 and 2 , wherein the channel ( 10 ) has a cross-sectional width of between 5 and 300 μm, preferably between 15 and 40 μm, and a cross-sectional height is preferably between 5 and 300 μm, preferably between 15 and 40 μm, with the cross-section taken perpendicular to the direction of flow.

4 . Apparatus according to one of the preceding claims, wherein the channel ( 10 ) comprises a section ( 12 ) having an approximately constant cross-section, wherein preferably, the cell shape measurement device measures the deformation of the cell within the section ( 12 ) having an approximately constant cross-section, the section having an approximately constant cross-section preferably having a length of between 25 μm to 20 mm, preferably within a range of 50 μm to 5 mm.

5 . Apparatus according to one of the preceding claims, wherein the channel ( 10 ) comprises one or more tapered sections, the tapering preferably being arranged along the direction of flow so that the channel either narrows or widens when moving along the direction of flow.

6 . Apparatus according to claim 5 , when dependent on claim 4 , wherein there is a first tapered section leading from the inlet of the channel ( 10 ) to the section ( 12 ) having an approximately constant cross-section, the first tapered section becoming narrower when moving from the inlet to the section ( 12 ) having an approximately constant cross-section, wherein there preferably is a second tapered section leading from the section ( 12 ) having an approximately constant cross-section to the outlet of the channel ( 10 ), the second tapered section becoming wider when moving from the section ( 12 ) having an approximately constant cross-section to the outlet of the channel ( 10 ).

7 . Apparatus according to one of the preceding claims, the analysis means being further arranged to carry out, prior to step b),
a step a) of obtaining, as a differential image, a difference between an image obtained when a cell is passing through the region of interest and the average image, and using this differential image in step b) for the determination of the cell contour.

8 . Apparatus according to claim 7 , wherein the image analysis device is arranged to carry out as part of step a) a further step a1) of setting the values of those pixels of the differential image whose absolute value is smaller than a certain preset value to a value which is ignored in the determination of the contour during step b).

9 . Apparatus according to claim 8 , wherein the certain preset value is obtained by:
measuring the fluctuation of a brightness value of a certain pixel or number of pixels over a predetermined time, and calculating the preset value based on that fluctuation, preferably as a fixed multiple of that fluctuation.

10 . Apparatus according to one of the claims 7 to 9 , wherein in step a), when obtaining the difference between an image obtained when a cell is passing through the region of interest and an average image obtained as an average of several images obtained of the region of interest, an absolute value of the difference is used when subtracting the images or where, when the difference has the opposite sign to that which occurs when a cell is present in the image, that pixel is set to a value which is ignored during the determination of the contour.

11 . Apparatus according to one of the preceding claims, wherein as part of step c), the deformation of the cell contour is obtained by comparing the cell contour obtained during step b) with a contour of the same cell before or after it is deformed.

12 . Apparatus according to one of claims 1 to 10 , wherein as part of step c), the deformation of the cell contour is obtained by comparing the cell contour obtained during step b) with an average contour of undeformed cells of the same type.

13 . Apparatus according to one of claims 5 to 12 , when dependent on claim 5 , wherein the region of interest is positioned such that it falls within one of the tapered sections, preferably completely.

14 . Apparatus according to one of claims 4 to 12 , when dependent on claim 4 , wherein the region of interest is positioned such that it falls within the section of the channel having an approximately constant cross-section, preferably completely.

15 . Apparatus according to one of the preceding claims, wherein the deformation of the cell contour is calculated by determining the circularity of the estimate of the contour.

16 . Apparatus according to one of the preceding claims, wherein the analysis means is arranged to carry out a step of smoothening the estimate of the contour of the cell.

17 . Apparatus according to one of the preceding claims, the apparatus being arranged to adjust a flow speed of the fluid within the channel at the region of interest to be within 0.01 and 500 m/s, preferably between 0.025 and 0.5 m/s.

18 . Apparatus according one of the preceding claims,
further comprising a light source ( 40 ) which is arranged to emit pulsed light towards the region of interest so as to illuminate cells passing through that region, wherein the duration of the light pulses is arranged such that it is shorter than the time over which the cell shape measurement device obtains information of a shape of a single cell.

19 . Apparatus according to claim 18 ,
the light source being a monochromatic light source, wherein preferably, the irradiance and color of the
light emitted by the monochromatic light source is adjusted taking into consideration t

Assignees

• Univ Dresden Tech

Inventors

• Guck Jochen
• Otto Oliver
• Rosendahl Philip

Classifications

• B01L3/502753

  characterised by bulk separation arrangements on lab-on-a-chip devices, e.g. for filtration or centrifugation · CPC title

• G06T7/11

  Region-based segmentation · CPC title

• G01N15/1484

  microstructural devices · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title

• B01L2300/0636

  Integrated biosensor, microarrays · CPC title