1. A device for preparing a reaction substrate having biosites for conducting multiplexed microassays to determine binding between a target analyte and a capture probe, including: a plurality of capillary tubes, each tube having a proximal end and a distal end; an attachment site for holding said capillary tubes at a point spaced from the distal ends of such capillary tubes; an array template for slidably holding each capillary tube near its distal end, and for allowing the distal end of each capillary tube to move with respect to the attachment site; at least one manifold for positioning the proximal end of each capillary tube within a corresponding supply chamber, wherein each supply chamber is capable of supplying a liquid reagent to at least one corresponding capillary tube; and a positioning device for precisely positioning the array template and said capillary tubes with respect to said reaction substrate and depositing liquid reagents from said distal end of said capillary tubes onto said reaction substrate as biosites.