Device for performing cell assays

1. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell in an extracellular fluid medium, and one or more sensor electrodes, the cell confinement cavity and the stimulating electrodes being arranged so that, in use, each cell is exposable to an electrical field generated by a potential difference applied across the stimulating electrodes, wherein the stimulating electrodes are spaced a distance apart such that the potential difference can induce field stimulation of each cell and simultaneously be below the level that would result in electrolysis of the extracellular fluid medium, and in which the electrical field includes a region of substantially uniform electrical field, each confined cell being exposable to the region, and in which the region of substantially uniform electrical field is bounded at one side by the floor of the cell confinement cavity.

2. A device according to claim 1 , in which in the region of substantially uniform electrical field the electrical field strength varies transversely to the electrical field lines by no more than 10%.

3. A device according to claim 1 , in which the region of substantially uniform electrical field extends along and/or transversely to the direction of the electrical field lines for a distance at least 2 μm.

4. A device according to claim 1 , in which the region of substantially uniform electrical field occupies a volume of at least 1 pL.

5. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell in an extracellular fluid medium, and one or more sensor electrodes, the cell confinement cavity and the stimulating electrodes being arranged so that, in use, each cell is exposable to an electrical field generated by a potential difference applied across the stimulating electrodes, wherein the stimulating electrodes are spaced a distance apart such that the potential difference can induce field stimulation of each cell and simultaneously be below the level that would result in electrolysis of the extracellular fluid medium, and in which the stimulating electrodes are coated with a chargeable surface area enhancing agent.

6. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell, and one or more sensor electrodes, the cell confinement cavity and the stimulating electrodes being arranged so that, in use, each cell is exposable to an electrical field generated by the stimulating electrodes, wherein the device further comprises at least one flow channel which is in fluid communication with the confinement cavity, and in which the electrical field includes a region of substantially uniform electrical field, each confined cell being exposable to the region, and in which the region of substantially uniform electrical field is bounded at one side by the floor of the cell confinement cavity.

7. A device according to claim 6 , in which in the region of substantially uniform electrical field the electrical field strength varies transversely to the electrical field lines by no more than 10%.

8. A device according to claim 6 , in which the region of substantially uniform electrical field extends along and/or transversely to the direction of the electrical field lines for a distance at least 2 μm.

9. A device according to claim 6 , in which the region of substantially uniform electrical field occupies a volume of at least 1 pL.

10. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell, and one or more sensor electrodes, the cell confinement cavity and the stimulating electrodes being arranged so that, in use, each cell is exposable to an electrical field generated by the stimulating electrodes, wherein the device further comprises at least one flow channel which is in fluid communication with the confinement cavity, and in which the stimulating electrodes are coated with a chargeable surface area enhancing agent.

11. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell, and one or more sensor electrodes, wherein the cell confinement cavity and the stimulating electrodes are arranged so that, in use, each confined cell is exposable to a region of substantially uniform electrical field generated by the stimulating electrodes, and in which the region of substantially uniform electrical field is bounded at one side by the floor of the cell confinement cavity.

12. A device according to claim 11 , in which in the region of substantially uniform electrical field the electrical field strength varies transversely to the electrical field lines by no more than 10%.

13. A device according to claim 11 , in which the region of substantially uniform electrical field extends along and/or transversely to the direction of the electrical field lines for a distance at least 2 μm.

14. A device according to claim 11 , in which the region of substantially uniform electrical field occupies a volume of at least 1 pL.

15. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell, and one or more sensor electrodes, wherein the cell confinement cavity and the stimulating electrodes are arranged so that, in use, each confined cell is exposable to a region of substantially uniform electrical field generated by the stimulating electrodes, and in which the stimulating electrodes extend in the direction perpendicular to the floor of the cell confinement cavity at opposing sides of the cell confinement cavity.

16. A device according to claim 15 , in which the stimulating electrodes extend in the direction perpendicular to the floor of the cell confinement cavity for a distance of at least 2 μm.

17. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell, and one or more sensor electrodes, wherein the cell confinement cavity and the stimulating electrodes are arranged so that, in use, each confined cell is exposable to a region of substantially uniform electrical field generated by the stimulating electrodes, and in which the stimulating electrodes are formed by electroplating from solution.

18. A device for performing cell assays, which device has at least one assay site, the site comprising a pair of stimulating electrodes, a cell confinement cavity for confining at least one cell, and one or more sensor electrodes, wherein the cell confinement cavity and the stimulating electrodes are arranged so that, in use, each confined cell is exposable to a region of substantially uniform electrical field generated by the stimulating electrodes, and in which the stimulating electrodes are coated with a chargeable surface area enhancing agent.