Apparatus for transporting a fluid within a channel leg of a microfluidic element
The invention relates to an apparatus for transporting a fluid in a channel leg of a microfluidic element, especially of a flow cell. According to the invention, a pressure source for pressurizing a front end face ( 42 ) in transport direction of the liquid which completely fills the channel leg in cross section is provided. The pressure source preferably comprises a closed space ( 17; 22; 34; 36, 38, 40 ), in which a compressed gas, for example air, is compressible by moving the front end face ( 42 ) of the fluid transported in the channel leg.
1. A device for transporting a fluid in a channel section of a microfluidic element, comprising: a channel section configured to form a fluid quantity to be transported that fills out the channel section in a plug-like manner; a transport pressure source that provides a pressure gas for applying a transport pressure, the transport pressure source being connected or connectable to the channel section and operative to apply the transport pressure in a transport direction against a rear end surface of the fluid quantity, wherein the transport pressure is adjustable; a back pressure source comprising a closed space that is connected to the channel section opposite to the transport pressure source, and in which a second pressure gas for applying a back pressure against a front end surface of the plug-like fluid quantity is enclosed so that a pressure level of the pressure gas in the closed space is varied when the plug-like fluid quantity is displaced in the channel section; and means for adjusting a desired position of the front end surface, the adjusting means being operative to adjust the pressure level of the transport pressure source to be equal to the back pressure level that corresponds to the desired position, based on a predetermined relationship between the position of the front end surface and the back pressure, and being operative to adjust the pressure level of the transport pressure source to be above or below the pressure level of the back pressure source so that the plug-like fluid quantity is movable in both directions in the channel section, the adjusting means including a pressure sensor configured to determine the back pressure at the front end surface, the pressure sensor being connected to a measuring device configured to automatically control transport of the fluid quantity.
2. The device according to claim 1 , wherein the transport pressure source is operative to adjust the pressure P 1 of the transport pressure source to be smaller than the pressure P 2 at the front end surface so as to reverse the transport direction.
3. The device according to claim 1 , wherein the back pressure source includes an assembly that defines the closed space so that the closed space is expandable by the pressure gas compressed in the closed space.
4. The device according to claim 1 , wherein the closed space is arranged within a plate forming the microfluidic element or/and by a container which is connectable to the plate.
5. The device according to claim 1 , wherein the channel section has at least one section widening for forming a chamber.
6. The device according to claim 1 , wherein several channel sections come together in a single channel section which is connected or is connectable to the back pressure source.
7. The device according to claim 6 , wherein the several channel sections are each connected or connectable to the transport pressure source.
8. The device according to claim 1 , wherein the channel section is branched in the transport direction into several channel sections which are each connected or connectable to the back pressure source.
9. The device according to claim 8 , wherein the branches are connected to different back pressure sources.