Drug delivery device with compressible drug reservoir

1. A capsule, comprising:

a reservoir defining a volume for containing a substance, the reservoir comprising a flexible wall and a hole providing a fluid passageway between the reservoir and an environment;

a piston disposed on a side of the flexible wall opposite the volume, the piston comprising an outer surface proximate a side of the flexible wall opposite the volume;

an adhesion interface adhering the outer surface of the piston to the side of the flexible wall opposite the volume to maintain conformity of the flexible wall to the piston, and

wherein at least one of the following holds: (1) the adhesion surface comprises a sticky coating on the surface of the piston, the sticky coating comprising a silicon based resin, (2) the adhesion surface comprises a magnetic coating, or (3) the adhesion surface comprises an electrostatically charged polymer.

2. The capsule of claim 1 , wherein the adhesion interface comprises a sticky coating on the surface of the piston and wherein the sticky coating comprises a silicon based resin.

3. The capsule of claim 1 , wherein the adhesion interface comprises a sticky coating on the flexible wall.

4. The capsule of claim 1 , wherein the adhesion surface comprises a magnetic coating.

5. The capsule of claim 1 , wherein the adhesion surface comprises an electrostatically charged polymer.

6. The capsule of claim 1 , wherein the flexible wall comprises at least one non-flexible part located at the adhesion interface.

7. The capsule of claim 1 , wherein the drug delivery device is a swallowable drug delivery device.

8. The capsule of claim 1 , wherein the drug delivery device is an implantable drug delivery device.

9. The capsule of claim 1 , further comprising an actuator for moving the piston relative to the hole in at least one of a first direction to compress the reservoir or a second direction to expand the reservoir.

10. The capsule of claim 1 , wherein the reservoir contains a substance to be dispensed, the piston being configured be pressed against the flexible wall to compress the reservoir and push an amount of the substance to be dispensed through the hole.

11. The capsule of claim 1 , wherein the piston is configured to be moved away from the hole and the adhesion interface retains the flexible wall against the piston to expand the reservoir, the expansion causing contents from the environment to enter the reservoir via the hole.

12. A capsule comprising:

a housing comprising a rigid, dome-shaped cap;

an opening through the rigid, dome-shaped cap;

a reservoir in the housing defined at least in part by a flexible wall spaced from the opening and an internal surface of the rigid, dome-shaped cap;

a piston disposed in the housing on a first side of the flexible wall opposite the opening and arranged to contact the first side of the flexible wall, the flexible wall separating the piston from contents in the reservoir, the piston being movable relative to the opening, and a portion of the piston having a domed shape; and

an adhesion interface adhering a portion of the first side of the flexible wall to a portion of the piston, the adhesion interface maintaining conformity of the flexible wall to the portion of the piston having the domed shape.

13. The capsule of claim 12 , wherein the flexible wall comprises at least one non-flexible p art and the non-flexible part is adhered to the piston at the adhesion surface.

14. The capsule of claim 12 , wherein the adhesion surface comprises a sticky coating on the portion of the piston or on the surface of the flexible wall.

15. The capsule of claim 12 , wherein the adhesion surface comprises a magnetic interface.

16. The capsule of claim 12 , wherein the adhesion surface comprises an electrostatic charge.

17. The capsule of claim 12 , wherein the reservoir is removable from the housing for refilling or replacement and the adhesion surface is remains intact on the piston when the reservoir is removed for refilling or replacement.