DropArray plate characteristics and processing. (A) DropArray plates consist of an array of circular areas on a polytetrafluoroethylene resin–coated glass slide attached to an aluminum support frame. (B) Each 2-mm diameter well is loaded with 2 μL of food coloring for better visualization. During an assay, the array of droplets is immersed in a perfluorocarbon-based liquid oil (gray), which virtually eliminates evaporation. (C) Steps involved during the plate washing procedure include the following: (i) the plate is sealed to the washer to create a large rinsing chamber; (ii) the rinsing chamber tilts to allow drainage of incubation oil; (iii) drainage of the incubation oil through gravity assist and a liquid pump; (iv) the rinsing chamber is filled with wash buffer (1× PBS, blue); (v) the rinsing chamber returns to the horizontal position for linear shaking; and (vi) after linear shaking, the rinsing chamber tilts to allow drainage of wash buffer.