-13 are top views of various exemplary analytical devices according to embodiments of the present invention; FIGS. 14 a and 14 b are a side view and top view, respectively, of an analytical device according to yet another embodiment of the present invention; FIGS. 15 a, 15 b, and 16 depict various systems used in connection with the Examples described below; FIG. 17 is a schematic illustration of