A microfluidic system for providing a sample fluid having a predetermined sample volume, the system comprising: a sample reservoir arranged for receiving a sample fluid; a first sample channel connected to the sample reservoir , the first sample channel branching off into a second sample channel ending in a first valve , and into a third sample channel , the third sample channel branching off into a fourth sample channel ending in a second valve , and into a fifth sample channel ending in a third valve , wherein the fifth sample channel has a predetermined volume; a buffer reservoir arranged for receiving a buffer fluid; a first trigger channel arranged to connect the buffer reservoir to the second valve ; a second trigger channel connecting the second valve and the first valve ; and an exit channel having a first end and a second end , wherein the first end is connected to the first valve ; wherein the first sample channel is arranged to draw sample fluid from the sample reservoir to fill the first, second, third, fourth, and fifth sample channels by capillary action; wherein the first trigger channel is arranged to draw buffer fluid from the buffer reservoir , by capillary action, to the exit channel via a fluid path comprising the second trigger channel , and to open the second valve and the first valve , whereby a further fluid path comprising the fourth sample channel , the third sample channel , and the second sample channel is opened up, allowing for sample present in the fourth sample channel , the third sample channel , and the second sample channel to be replaced by buffer fluid from the first trigger channel and flow into the exit channel together with buffer fluid from the second trigger channel , thereby isolating a sample fluid present in the fifth sample channel from adjacent sample fluid, wherein a volume of the isolated sample fluid corresponds to the volume of the fifth sample channel , thereby providing the sample fluid having the predetermined sample volume. a sample reservoir arranged for receiving a sample fluid; a first sample channel connected to the sample reservoir , the first sample channel branching off into a second sample channel ending in a first valve , and into a third sample channel , the third sample channel branching off into a fourth sample channel ending in a second valve , and into a fifth sample channel ending in a third valve , wherein the fifth sample channel has a predetermined volume; a buffer reservoir arranged for receiving a buffer fluid; a first trigger channel arranged to connect the buffer reservoir to the second valve ; a second trigger channel connecting the second valve and the first valve ; and an exit channel having a first end and a second end , wherein the first end is connected to the first valve ; wherein the first sample channel is arranged to draw sample fluid from the sample reservoir to fill the first, second, third, fourth, and fifth sample channels by capillary action; wherein the first trigger channel is arranged to draw buffer fluid from the buffer reservoir , by capillary action, to the exit channel via a fluid path comprising the second trigger channel , and to open the second valve and the first valve , whereby a further fluid path comprising the fourth sample channel , the third sample channel , and the second sample channel is opened up, allowing for sample present in the fourth sample channel , the third sample channel , and the second sample channel to be replaced by buffer fluid from the first trigger channel and flow into the exit channel together with buffer fluid from the second trigger channel , thereby isolating a sample fluid present in the fifth sample channel from adjacent sample fluid, wherein a volume of the isolated sample fluid corresponds to the volume of the fifth sample channel , thereby providing the sample fluid having the predetermined sample volume. <EOS>