Xurography actuated valving for centrifugal flow control

Abstract

We introduce a novel instrument controlled valving scheme for centrifugal platforms which is based upon xurography. In a first approach, which is akin to previously presented event-triggered flow control, the valves are composed of a pneumatic chamber sealed by a dissolvable film (DF) and by a pierceable membrane. Liquid is initially prevented from wetting the DF by the counter pressure of a trapped gas. Via a channel, this pocket is pneumatically connected to a vent, sealed by the pierceable membrane, located on the top surface of the disc. By scouring the top surface of the disc, along a pre-defined track by a robotic knife-cutter, the trapped gas is released and so the liquid can wet and disintegrate the DF. In order to automate assay protocols without the need to integrate DFs, we extend this xurography-based flow control concept by selective venting of chambers subjected to pneumatic over-pressure or vacuum suction. Unlike most instrument controlled flow-control mechanisms, in this approach to valve actuation can occur during disc rotation. To demonstrate the potential of this flow control approach, we designed a disc architecture to automate the liquid handling as the backbone of a biplex liver assay panel. We demonstrate valve actuation during rotation, using the robotic arm, using this disc with visualisation via dyed water. We then demonstrate the biplex liver assay, using calibration reagent, by stopping the disc and manually piercing the membrane to actuate the same valves.