Methods and apparatus for forming a channel through a polymer layer using a protrusion

1. A method comprising:

forming a first polymer layer;

positioning a structure on the first polymer layer, wherein the structure comprises a sensor;

forming, in a molding piece, a body-mountable device by forming a second polymer layer over the structure positioned on the first polymer layer, wherein the first polymer layer defines a first side of the body-mountable device and the second polymer layer defines a second side of the body-mountable device opposite the first side, and wherein the molding piece comprises a surface that supports the second polymer layer as the second polymer layer is being formed and a protrusion that extends from the surface to the sensor through the second polymer layer as the second polymer layer is being formed; and

removing the body-mountable device from the molding piece, wherein the body-mountable device removed from the molding piece has a channel to the sensor formed by the protrusion.

2. The method of claim 1 , wherein the protrusion comprises a rod and a spring, wherein the rod has a first end and a second end, and wherein the spring is connected to the second end of the rod and configured to press the first end of the rod against the sensor during formation of the second polymer layer.

3. The method of claim 2 , wherein the first end of the rod comprises a compliant material.

4. The method of claim 3 , wherein the compliant material fully covers the sensor during formation of the second polymer layer.

5. The method of claim 2 , wherein the rod comprises a complaint material.

6. The method of claim 2 , wherein the first end of the rod is wider than the sensor.

7. The method of claim 6 , wherein the second end of the rod is wider than the first end of the rod.

8. The method of claim 2 , wherein a dimension of the rod defines a dimension of the channel.

9. The method of claim 8 , wherein a dimension of the first end of the rod defines a dimension of the channel.

10. The method of claim 2 , wherein the spring is further configured to deform a distance when pressing the first end of the rod against the sensor during formation of the second polymer layer.

11. The method of claim 2 , further comprising:

applying a non-stick coating to at least one of the sensor or the rod.

12. The method of claim 1 , wherein forming the second polymer layer over the structure positioned on the first polymer layer comprises:

providing a polymer material on the surface of the molding piece;

orienting an additional molding piece over the polymer material on the surface of the molding piece, wherein the additional molding piece holds the structure positioned on the first polymer layer, and wherein the orienting of the additional molding piece positions the sensor directly above the protrusion;

bringing the molding piece and the oriented additional molding piece together into a forming position, wherein in the forming position (i) the polymer material on the surface of the molding piece contacts the structure and the first polymer layer held by the additional molding piece and (ii) the sensor contacts the protrusion; and

in the forming position, curing the polymer material to form the second polymer layer.

13. The method of claim 12 , wherein the protrusion comprises a rod having a first end, and wherein providing the polymer material on the surface of the molding piece comprises providing the polymer material on the surface of the molding piece, such that the first end of the rod is located above the polymer material.

14. The method of claim 13 , wherein the rod is moveable, and wherein bringing the molding piece and the oriented second molding piece together into the forming position moves the rod downward such that a portion of the first end of the rod is substantially flush with a surface of the polymer material.