The ornamental design for microwell strip, as shown and described.
FIG. 1 is a perspective view of the new design;
FIG. 2 is a front view thereof (the rear view is a mirror image of the front view);
FIG. 3 is a right side view thereof (the left side view is a mirror image of the right side view);
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a sectional view of a microwell, taken along line 6-6 in FIG. 4, showing interior structure, wherein each micro-well has a similar exterior and interior structure.
The portions of the drawings shown in broken lines depict features forming no part of the claimed design.