Microfluidic device

1. A method of manufacturing a microfluidic device, the method comprising:

injection moulding a substrate using a master die having at least one outer stepped formation; and

forming at least one microstructured formation having an outer rim, the depth of the outer rim being shallower than that of the microstructured formation;

wherein the injection moulding step comprises moulding the substrate using a master die so that a surface of the substrate includes one or more microstructured formations complementary to respective moulding formations on the master die and one or more anchor formations complementary to respective anchor formations on the master die, the microstructured formations including a microfluidic channel and forming at least part of a microfluidic channel network comprising a plurality of microfluidic channels, in which one or more of the moulding formations on the master die comprise the outer stepped formation so that the respective complementary microstructured formations on the substrate include the outer rim shallower than the microstructured formation, the rim not being in the plane of the substrate; and

wherein the master die comprises one or more respective anchor formations having a greater height or depth than the maximum height or depth of the one or more moulding formations; and

wherein the one or more complementary anchor formations in the surface of the substrate are not fluidly connected to the microfluidic channel.

2. A method according to claim 1 , in which at least a portion of the outer rim is substantially parallel to the plane of the substrate surface.

3. A method according to claim 1 , in which the outer rim has a depth of 1 μm-100 μm.

4. A method according to claim 3 , in which the outer rim has a depth of 1 μm-10 μm.

5. A method according to claim 1 , in which one or more of the moulding formations on the master die are chamfered so as to be narrower at a distal end than at a proximal end.

6. A method according to claim 1 , comprising the step of providing one or more ejection pins, movable so as to drive the master die and the moulded substrate apart, at positions associated with the positions of the anchor formations on the master die.

7. A method according to claim 6 , in which one or more ejection pins are disposed within respective anchor formations on the master die.

8. A method according to claim 7 , in which the one or more ejection pins are disposed centrally within respective anchor formations on the master die.