Assay systems with adjustable fluid communication

1. A device for assaying a plurality of biological or chemical samples, comprising: a frame; and a plurality of wells disposed in the frame and addressable individually with fluid, each well including a plurality of sub-wells addressable with fluid either (a) individually, or (b) as two or more groups,

wherein each well has an outer wall and at least two inner walls of lower height than the outer wall and different in height from each other, and wherein the at least two inner walls extend to different heights to form at least two levels, thereby dividing the well into the sub-wells and the two or more groups of sub-wells.

2. The device of claim 1 , wherein each group is a linear array of sub-wells.

3. The device of claim 1 , wherein the two or more groups are arrayed linearly within each well.

4. The device of claim 1 , wherein a relatively low level of fluid over a sub-well disposes the sub-well in fluid isolation from the other sub-wells, wherein a relatively medium level of fluid over the sub-well disposes the sub-well in fluid communication with other sub-wells of only one of the two or more groups, and wherein a relatively high level of fluid over the sub-well disposes the plurality of sub-wells in fluid communication.

5. The device of claim 1 , wherein the at least two inner walls include at least one higher wall dividing the well into rows or columns and at least one lower wall dividing the rows or columns into individual sub-wells.

6. The device of claim 1 , wherein an insert defines the height of one or more of the inner walls of the sub-wells.

7. The device of claim 1 , wherein the inner walls divide the well into groups of sub-wells disposed in rows or columns.

8. The device of claim 1 , wherein the wells are arranged in rows and columns.

9. The device of claim 1 , wherein each well is at least substantially rectangular in a horizontal plane.

10. The device of claim 1 , wherein the frame, the plurality of wells, and the plurality of sub-wells are unitary.

11. A device for assaying a plurality of biological or chemical samples, comprising:

a frame;

a plurality of wells disposed in the frame and addressable individually with fluid;

a set of sub-wells disposed in each well and addressable individually or as a group by adjusting fluid levels, wherein the heights of the sub-wells are lower than that of said wells; and

a set of relatively smaller sub-wells disposed in each sub-well and addressable individually or as a group by adjusting fluid levels, wherein the height of each relatively smaller sub-well is lower than that of said sub-wells.