Encoded microcarriers, assay system using them and method for performing an assay

1. An encoded microcarrier comprising a readable code for identifying the microcarrier, said microcarrier comprising:

a body having a detection surface to detect a chemical and/or biological reaction, and

a plurality of spaced-apart spacing elements projecting outward from a periphery of the body, each spacing element having a distal end, wherein the respective distal ends of the plurality of spacing elements together collectively form a contacting surface that is in a plane substantially parallel to the detection surface, said contacting surface having an area size that is less than 20% of an area size of the detection surface,

wherein said plurality of spacing elements are shaped such that, when the encoded microcarrier is laid on a flat plane with the detection surface and the contacting surface of the spacing element facing said flat plane, a gap exists between said flat plane and the detection surface.

2. An encoded microcarrier according to claim 1 , wherein the area size of said contacting surface is less than 15% of the area size of said detection surface.

3. An encoded microcarrier according to claim 1 , wherein said contacting surface is generally planar.

4. An encoded microcarrier according to claim 1 , wherein each spacing element is shaped as a truncated cylinder.

5. An encoded microcarrier according to claim 1 , wherein the detection surface has at least an area wherein, when said microcarrier is laid on a flat plane with the detection surface facing said flat plane, each point of said area belongs to two different cross-sections of said encoded microcarrier which are perpendicular to each other and to said flat plane, said cross-sections being free of said plurality of spacing elements.

6. An encoded microcarrier according to claim 1 , wherein, when the encoded microcarrier is laid on a flat plane with a detection surface facing said flat plane, the greatest distance (d) between said detection surface and said flat plane is greater than 5% of the greatest height (H) between the contacting surface and an upper surface of the encoded microcarrier.

7. An encoded microcarrier according to claim 1 , wherein the detection surface is generally planar.

8. An encoded microcarrier according to claim 7 , wherein each of said plurality of spacing elements is shaped such that, when the encoded microcarrier is laid on a flat plane with the detection surface facing said flat plane, said flat plane and said detection surface are substantially parallel to each other.

9. An encoded microcarrier according to claim 1 , wherein each of said plurality of spacing elements protrudes from the detection surface in a direction generally perpendicular to the detection surface.

10. An encoded microcarrier according to claim 1 , wherein said encoded microcarrier comprises at least three spacing elements, said at least three spacing elements face said flat plane when the encoded microcarrier is laid on the flat plane.

11. An encoded microcarrier according to claim 1 , wherein each of the plurality of spacing elements is located at the peripheral edge of the encoded microcarrier.

12. An assay system comprising

a plurality of encoded microcarriers comprising a readable code for identifying the microcarrier, each said microcarrier comprising:

a body having a detection surface to detect a chemical and/or biological reaction, and

a plurality of spaced-apart spacing elements projecting outward from a periphery of the body, each spacing element having a distal end, wherein the respective distal ends of the plurality of spacing elements together collectively form a contacting surface that is in a plane substantially parallel to the detection surface, said contacting surface having an area size that is less than 20% of an area size of the detection surface,

wherein said plurality of spacing elements are shaped such that, when the encoded microcarrier is laid on a flat plane with the detection surface and the contacting surface of the spacing element facing said flat plane, a gap exists between said flat plane and the detection surface,

an assay device having at least a microfluidic channel shaped to accommodate a plurality of said encoded microcarriers, said microfluidic channel having at least an observation wall through which an assay is monitorable, wherein the spacing elements of each encoded microcarrier are shaped to ensure that, when said encoded microcarrier is introduced in said microfluidic channel with said detection surface facing said observation wall, a gap exists between said detection surface and said observation wall to allow a circulation of fluid in said gap.

13. A method for performing a chemical and/or biological assay comprising a step of using at least an encoded microcarrier comprising a readable code for identifying the microcarrier, said microcarrier comprising:

a body having a detection surface to detect a chemical and/or biological reaction, and

a plurality of spaced-apart spacing elements projecting outward from a periphery of the body, each spacing element having a distal end, wherein the respective distal ends of the plurality of spacing elements together collectively form a contacting surface that is in a plane substantially parallel to the detection surface, said contacting surface having an area size that is less than 20% of an area size of the detection surface,

wherein said plurality of spacing elements are shaped such that, when the encoded microcarrier is laid on a flat plane with the detection surface and the contacting surface of the spacing element facing said flat plane, a gap exists between said flat plane and the detection surface,

wherein a chemical and/or biological reaction is monitored on the detection surface of said encoded microcarrier.

14. A method according to claim 13 , further comprising a step of monitoring the at least one chemical and/or biological reaction through an observation wall of an assay device.

15. A method according to claim 13 , further comprising a step of reading the attached code of said encoded microcarrier through an observation wall of an assay device.