METHOD AND DEVICE FOR READING AN EMULSION

• US 20110188717A1
• Filed: 07/13/2009
• Published: 08/04/2011
• Est. Priority Date: 07/15/2008
• Status: Active Grant

• Current Assignee: École Supérieure de Chimie Industrielles de la Ville de Paris, Universite Paris CITE
• Original Assignee: Centre National De La Recherche Scientifique, Universite Paris Diderot Paris 7, University Pierre et Marie Curie
• Inventors: Bremond, Nicolas, Sylvestre, Julien, Baudry, Jean, Boitard, Laurent, Bibette, Jerome
• Granted Patent: US 8,798,341 B2
• Time in Patent Office: Days
• US Class Current: 382/128
• CPC Class Codes: G01N 15/1433 using image recognition
• CPC Class Codes: G01N 2015/003 in liquids, e.g. emulsion
• CPC Class Codes: G01N 2015/0092 Monitoring flocculation or agglomeration

Abstract

A method for reading an emulsion (3) including droplets and a continuous phase surrounding the droplets, the method includes:

• • two-dimensional scanning of the emulsion (3), and
  • construction of a two-dimensional image of the emulsion (3) based on the scanning. Preferably, the droplets do not move during scanning, for example by solidifying the continuous phase or by using a two-dimensional compact or semi-compact network of droplets. The method can further include time-based monitoring of a chemical or biological reaction taking place in at least one of the droplets. A device implementing this method is also described. The method is applicable for the detection and/or sorting of microdroplets performing the role of microreactors or containing specific cells or molecules, in fields such as gene expression or diagnosis.

Claims

1-44. -44. (canceled)

45. Method for reading an emulsion (3) comprising droplets (21, 22) and a continuous phase (23) which surrounds the droplets (21), said method comprising:

two-dimensional scanning of the emulsion (3) by an optical system (4),

construction of a two-dimensional image (24) of the emulsion (3) based on said scanning.

46. Method according to claim 45, characterized in that the droplets do not move during scanning.

47. Method according to claim 45, characterized in that the continuous phase (23) is solid during scanning.

48. Method according to claim 45, characterized in that the continuous phase has a melting point above 37°

C.

49. Method according to claim 45, characterized in that the continuous phase has a melting point above 40°

C.

50. Method according to claim 45, characterized in that the continuous phase has a melting point above 50°

C.

51. Method according to claim 45, characterized in that during scanning of the emulsion, the emulsion is maintained at a temperature below the melting point of the continuous phase.

52. Method according to claim 45, characterized in that the droplets of the emulsion form a two-dimensional network of droplets.

53. Method according to claim 52, characterized in that the volume fraction of droplets in the emulsion is greater than or equal to 40%.

54. Method according to claim 52, characterized in that the volume fraction of droplets in the emulsion is greater than or equal to 60%.

55. Method according to claim 45, characterized in that the droplets of the emulsion form a colloidal solid.

56. Method according to claim 45, characterized in that the continuous phase (23) comprises a surfactant.

57. Method according to claim 45, characterized in that during scanning of the emulsion, the emulsion is stored in a receptacle.

58. Method according to claim 57, characterized in that during scanning of the emulsion, the receptacle is maintained at a roughly constant temperature, to an accuracy of plus or minus 0.1°

C.

59. Method according to claim 57, characterized in that the receptacle comprises a flat wall, which during scanning of the emulsion is in contact with the emulsion and is arranged horizontally with a vertical difference in level of less than 5 micrometres over a horizontal distance of 2 centimetres.

60. Method according to claim 57, characterized in that the receptacle comprises two approximately parallel surfaces which during scanning of the emulsion hold each of the droplets in place.

61. Method according to claim 45, characterized in that it further comprises time-based monitoring of a chemical or biological reaction taking place in at least one of the droplets (22), said monitoring comprising repetition of the steps of scanning and construction.

62. Method according to claim 45, characterized in that it further comprises locating droplets (22) comprising a given type of molecule or cell by analysing the two-dimensional image (24) of the emulsion (3).

63. Method according to claim 62, characterized in that locating comprises using an algorithm for thresholding and segmentation of the two-dimensional image.

64. Method according to claim 45, characterized in that it further comprises sampling of the droplets (22) comprising the given type of molecule or cell.

65. Method according to claim 64, characterized in that sampling comprises:

movement of one end of a micropipette (18) to coordinates where a droplet (22) comprising the given type of molecule or cell has been located, and

aspiration of this droplet (22) by the micropipette (18).

66. Method according to claim 45, characterized in that it further comprises counting of droplets (22) comprising a given type of molecule or cell by analysing the two-dimensional image (24) of the emulsion (3).

67. Method according to claim 66, characterized in that

counting comprises using an algorithm for thresholding and segmentation of the two-dimensional image.

68. Method according to claim 45, characterized in that construction of the two-dimensional image comprises, during scanning:

projection of different partial images of the emulsion via the optical system (4) onto a detector (11),

combining the different partial images of the emulsion acquired by the detector (11).

69. Method according to claim 68, characterized in that the partial images are images of fluorescence signals emitted by the emulsion.

70. Method according to claim 45, characterized in that the emulsion (3) is an inverted emulsion of water droplets (21, 22) in oil (23).

71. Method according to claim 45, characterized in that the emulsion (3) is spread out so as to have a thickness between 1 and 100 layers of droplets.

72. Method according to claim 71, characterized in that the optical system (4) has a depth of field roughly equal to or greater than the thickness of the spread-out emulsion (3).

73. Method according to claim 45, characterized in that it further comprises:

placement of the emulsion (3) between two parallel plates (14, 15), at least one of which (15) is transparent (24),

a shearing movement between the two plates (14, 15) until the emulsion (3) is monodisperse.

85. Device according to claim 54, characterized in that the sampling means comprise:

a micropipette (18),

means (19) for moving an end of the micropipette to coordinates of a droplet (22) comprising the given type of molecule or cell and that has been located by the locating means (6), and

means for aspirating this droplet by the micropipette.

74. Device for reading an emulsion (3) comprising droplets (21, 22) and a continuous phase (23) which surrounds the droplets (21), said device comprising:

a receptacle (2) for receiving the emulsion (3),

an optical system (4),

means (5) for carrying out two-dimensional scanning of the emulsion (3) by the optical system (4),

means (11, 6) for constructing a two-dimensional image (24) of the emulsion based on a two-dimensional scan of the emulsion.

75. Device according to claim 74, characterized in that it comprises means for “

freezing”

the droplets during scanning.

76. Device according to claim 74, characterized in that it comprises means (17) for maintaining the emulsion (3) at a temperature below the melting point of the continuous phase during scanning of the emulsion.

77. Device according to claim 74, characterized in that it comprises means for preparing the emulsion, said means being arranged so that the droplets of the emulsion form a two-dimensional network of droplets, preferably having a volume fraction of droplets in the emulsion greater than or equal to 40%, more preferably greater than or equal to 60%, and preferably forming a colloidal solid.

78. Device according to claim 77, characterized in that the means for preparation comprise a chamber for creaming or sedimentation of the droplets and means for sampling, from said chamber, droplets diluted in the continuous phase according to a given volume fraction of droplets.

79. Device according to claim 74, characterized in that it comprises means for maintaining the receptacle at a roughly constant temperature during scanning of the emulsion, preferably to an accuracy of plus or minus 0.1°

C.

80. Device according to claim 74, characterized in that the receptacle comprises a flat wall arranged so that it is in contact with the emulsion during scanning of the emulsion and is arranged horizontally with a vertical difference in level of less than 5 micrometres over a horizontal distance of 2 centimetres.

81. Device according to claim 74, characterized in that the receptacle comprises two approximately parallel surfaces arranged to hold each of the droplets in place during scanning of the emulsion.

82. Device according to claim 74, characterized in that it further comprises means (6) for time-based monitoring of a chemical or biological reaction taking place in at least one of the droplets (22).

83. Device according to claim 74, characterized in that it further comprises means (6) for locating droplets (22) comprising a given type of molecule or cell, the locating means comprising means for analysing the two-dimensional image (24) of the emulsion.

84. Device according to claim 74, characterized in that it comprises means (18, 19) for sampling droplets (22) comprising the given type of molecule or cell.

86. Device according to claim 74, characterized in that it further comprises means (6) for counting droplets (22) comprising a given type of molecule or cell, the counting means comprising means for analysing the two-dimensional image (24) of the emulsion.

87. Device according to claim 74, characterized in that the means for constructing the two-dimensional image comprise:

a detector (11) on which optical system (4) is set up for projecting different partial images of the emulsion (3) during a scan,

means (6) for combining the different partial images of the emulsion acquired by the detector (11) during scanning.

88. Device according to claim 74, characterized in that the receptacle (2) is arranged so that the emulsion (3) is spread out so as to have a thickness between 1 and 100 layers of droplets (21, 22).

89. Device according to claim 88, characterized in that the optical system (4) has a depth of field roughly equal to or greater than the thickness of the spread-out emulsion (3).

90. Device according to claim 74, characterized in that the receptacle (2) comprises two parallel plates (14, 15), at least one of which (15) is transparent, and means (16) for applying a shearing movement between the two plates (14, 15) until the emulsion (3) is monodisperse.