Patent ID: 8319126

Claim:
A dispensing apparatus comprising: a housing defining a channel; a plunger slidably engaged for movement along the channel; a substrate with one or more passages is disposed in the channel on one side of the plunger, each of the passages has two or more openings; at least one liquid in each of the one or more passages has a volume which exceeds an internal volume of each the one or more passages and forms a liquid drop around each of the openings, wherein the liquid drops are fluidly connected to one another, each of the liquid drops is individually adjustable between two or more sizes, and each of the sizes and a location of each of the liquid drops defines one of two or more switch positions; at least one fluid is located in the channel on the one side of the plunger and substantially surrounding the liquid drops; and a force application system that is configured to individually and selectively apply a force on the liquid in each of the one or more passages to control switching between the two or more switch positions of each of the liquid drops, wherein one or more of the switch positions move the plunger along the inner surface of the channel away from the substrate.