Micropores and methods of making and using thereof

1. A method for forming a micropore between two isotropic wet etched features in a substrate which comprises

forming the two features by a single-level isotropic wet-etch using an etchant and a mask distance between a mask for each feature that is less than 2× a set etch depth.

2. The method of claim 1 , wherein the mask distance is

g= √{square root over (4 ·d 2 −(2( h−b )) 2 )}

wherein d is the set etch depth, h is the desired height of the micropore, and b is a calculated systematic error.

3. The method according to claim 2 , wherein the calculated systematic error is calculated by

obtaining measured heights for a plurality of calibration micropores which were formed by single-level isotropic wet etching the features in the substrate with the etchant at the set etch depth and at a plurality of mask distances ranging from about 2× or less the set etch depth; and

using nonlinear regression analysis to fit the measured heights to the following equation

h

m

=

1

2

⁢

4

⁢

d

2

-

g

2

+

b

where h m is the measured height of the calibration micropore.

4. The method according to claim 3 , wherein the plurality of calibration micropores comprises about 15 to 20 calibration micropores.

5. The method of claim 1 , wherein the mask distance is

g=√{square root over (4·d 2 −(w−b) 2 )} where the micropore is a point-to-point micropore, or

g

=

d

+

1

2

⁢

4

·

d

2

-

(

w

-

b

)

2

where the micropore is a point-to-edge micropore,

wherein d is the set etch depth, w is the desired width of the micropore, and b is a calculated systematic error.

6. The method according to claim 5 , where the micropore is the point-to-point micropore, the calculated systematic error is calculated by

obtaining measured widths for a plurality of calibration micropores which were formed by single-level isotropic wet etching the features in the substrate with the etchant at the set etch depth and at a plurality of mask distances ranging from about 2× or less the set etch depth; and

using nonlinear regression analysis to fit the measured widths to the following equation

w m =√{square root over (4 ·d 2 −g 2 )}+ b

where w m is the measured width of the calibration micropore.

7. The method according to claim 5 , wherein the micropore is the point-to-edge micropore, the calculated systematic error is calculated by

obtaining measured widths for a plurality of calibration micropores which were formed by single-level isotropic wet etching the features in the substrate with the etchant at the set etch depth and at a plurality of mask distances ranging from about 2× or less the set etch depth; and

using nonlinear regression analysis to fit the measured widths to the following equation

w m =2√{square root over ((2 d−g ) g )}+ b

where w m is the measured width of the calibration micropore.

8. The method according to claim 1 , wherein the micropore has a zero thickness.

9. The method according to claim 1 , wherein the width of the micropore is about two times the height of the micropore.

10. The method according to claim 1 , wherein the micropore is less than about 7 μm in height.

11. The method according to claim 1 , which further comprises attaching a cover to the substrate such that the cover forms a wall of the micropore, the features or both.

12. The method of claim 11 , wherein the cover comprises a micropore which is aligned over the micropore in the substrate to form a compound micropore having a top portion and a bottom portion.

13. The method according to claim 12 , wherein the center of the top portion is centered over the center of the bottom portion or the center of the top portion is off-center over the center of the bottom portion.

14. The method according to claim 12 , wherein the top portion and the bottom portion are symmetrical or asymmetrical.

15. The method according to claim 1 , wherein the mask distance, the calculated systemic error, or both are calculated with a computer.