Centrifugo-pneumatic switching of liquid

Method for switching liquid from a liquid retaining area into downstream fluidic structures by using a fluidic module, the module comprising:

• a liquid retaining area into which liquid can be introduced, at least two fluid paths fluidically connecting the liquid retaining area to downstream fluidic structures, wherein at least a first fluid path of the at least two fluid paths comprises a syphon channel, wherein a syphon crest of the syphon channel is located radially inside of a radial outermost position of the liquid retaining area, wherein the syphon crest is an area of the syphon channel with minimum distance to the center of rotation, wherein the downstream fluidic structures are at most vented via a vent delay resistor when the liquid is introduced into the liquid retaining area, such that an enclosed gas volume or a gas volume merely vented via the vent delay resistor results in the downstream fluidic structures when the liquid is introduced into the liquid retaining area, and a ratio of a centrifugal pressure effected by a rotation of the fluidic module to a pneumatic pressure prevailing in the gas volume at least temporarily prevents the liquid from reaching the downstream fluidic structures through the at least two fluid paths, wherein transfer of at least part of the liquid to the downstream fluidic structures through the first fluid path and venting of at least part of the gas volume into the liquid retaining area through a second fluid path of the at least two fluid paths is effected by changing the ratio of the centrifugal pressure to the pneumatic pressure, the method comprising:
• introducing at least one liquid into the liquid retaining area and retaining the liquid in the liquid retaining area by rotating the fluidic module, such that the liquid is retained in the liquid retaining area in a quasi-stationary equilibrium dominated by the centrifugal pressure and the pneumatic pressure;
• and changing the ratio of the centrifugal pressure to the pneumatic pressure in order to transfer the liquid at least partly through the first fluid path into the downstream fluidic structures and to vent the gas volume at least partly into the liquid retaining area through the second fluid path of the two at least fluid paths, wherein
• a) retaining the liquid in the liquid retaining area comprises generating a pneumatic overpressure in the downstream fluidic structures prior to initiating the transfer, and changing the ratio of the centrifugal pressure to the pneumatic pressure comprises increasing the rotational speed of the fluidic module, increasing the hydrostatic height of the liquid and/or reducing the pneumatic pressure, or
• b) retaining the liquid in the liquid retaining area comprises generating a negative pressure in the downstream fluidic structures in order to adjust and retain menisci in the liquid retaining area and the first and second fluid paths without transferring the liquid into the downstream fluidic structures through the first fluid path, and wherein changing the ratio of the centrifugal pressure to the pneumatic pressure comprises reducing the rotational speed of the fluidic module and/or reducing the pneumatic pressure in the downstream fluidic structures.