US Patent 7438857 Liquid handling tool having porous plunger

A robotically manipulable sample handling tool, such as a colony picking head or robotic pipetting tool, includes needles arranged on the tool. Actuators are associated with each needle to control flow for the needle. A plurality of plungers are each associated with a needle, and movement of the plungers can actuate a corresponding needle. Each of the plungers has a passageway that may be opened or closed, e.g., to move the corresponding needle and/or draw fluid into/expel fluid from the needle when the plunger is moved in the tool body. The actuators are arranged so that plunger passageways may be individually controlled by a controller.