MEMS ELECTROCHEMICAL BELLOWS ACTUATOR

• US 20100222769A1
• Filed: 02/19/2010
• Published: 09/02/2010
• Est. Priority Date: 02/20/2009
• Status: Active Grant

• Current Assignee: University of Southern California
• Original Assignee: University of Southern California
• Inventors: Li, Po-Ying, Hoang, Tuan, Meng, Ellis
• Granted Patent: US 8,579,885 B2
• Time in Patent Office: Days
• US Class Current: 604/891.100
• CPC Class Codes: A61M 2210/0612 Eyes
• CPC Class Codes: A61M 5/14276 specially adapted for implantation

Abstract

An implantable fluid delivery system may include a fluid reservoir configured to hold a supply of fluid, to dispense that fluid under the control of an actuator, and to be implanted within the body of a living host. An actuator within the fluid reservoir may cause the fluid to be controllably dispensed from the fluid reservoir. The actuator may include a bellows configured to expand in a direction when inflated. The bellows may have folds with surfaces which run substantially perpendicular to the direction of expansion in a collapsed state and which define a stacked set of convolutions. Each convolution may have a collapsed height of no more than 1 mm and a width perpendicular to the direction of expansion of no more than 8 mm. Electrodes may be configured to come in electrical contact with an electrolyte within the bellows and to cause electricity to run through the electrolyte, thereby causing the electrolyte to break down into a gas and, in turn, to cause the bellows to expand. Methods of making the bellows which utilize stacked sheets are also disclosed.

Claims

1. An implantable fluid delivery system comprising:

a fluid reservoir configured to hold a supply of fluid, to dispense that fluid under the control of an actuator, and to be implanted within the body of a living host; and

an actuator within the fluid reservoir configured to cause the fluid to be controllably dispensed from the fluid reservoir, the actuator including;

a bellows configured to expand in a direction when inflated, the bellows having folds with surfaces which run substantially perpendicular to the direction of expansion in a collapsed state and which define a stacked set of convolutions, each of which has a collapsed height of no more than 1 mm and a width perpendicular to the direction of expansion of no more than 8 mm; and

electrodes configured to come in electrical contact with an electrolyte within the bellows and to cause electricity to run through the electrolyte, thereby causing the electrolyte to break down into a gas and, in turn, to cause the bellows to expand in the direction of expansion.

2. The implantable fluid delivery system of claim 1 wherein the implantable fluid delivery system is configured to fit within a human eye.

3. The implantable fluid delivery system of claim 1 wherein the implantable fluid delivery system is configured such that the fluid and the electrolyte cannot mix.

4. The implantable fluid delivery system of claim 3 wherein the actuator creates a sealed chamber from which electrolyte cannot leak.

5. The implantable fluid delivery system of claim 1 wherein the stacked set of convolutions in the bellows taper in width.

6. The implantable fluid delivery system of claim 1 wherein the bellows are made of Parylene C.

7. A method for making a bellows which expands in a direction when inflated, the method comprising in the order recited:

stacking stencil sheets, each of which has an opening within the stencil sheet which corresponds to the shape of the exterior surface of a cross-sectional slice of the bellows, the stacked stencil sheets collectively forming a cavity, the interior of which collectively corresponds to the shape of the exterior surface of the bellows;

filling the cavity formed by the stacked stencil sheets with a filler;

removing the filler from within the stacked stencil sheets after it has hardened;

coating the hardened filler with a coating; and

removing the coating from the hardened filler after the coating has hardened, the removed and hardened coating being the bellows.

8. The method of claim 7 further comprising placing tape on a substrate prior to stacking the stencil sheets of material and wherein the stencil sheets are stacked on the tape.

9. The method of claim 7 wherein the stencil sheets are made of PDMS.

10. The method of claim 7 wherein the filler is PEG.

11. The method of claim 7 wherein the coating is Parylene C.

12. The method of claim 7 wherein the bellows have a structure which can hold an electrolyte without leakage of the electrolyte through the walls of the bellows.

13. The method of claim 7 wherein the method creates bellows which are configured to expand in a direction when inflated and which has folds with surfaces which run substantially perpendicular to the direction of expansion in a collapsed state and which define a stacked set of convolutions, each of which has a collapsed height of no more than 1 mm and a width perpendicular to the direction of expansion of no more than 8 mm.

14. A method for making a bellows which expands in a direction when inflated, the method comprising in the order recited:

stacking mold sheets, each of which has a perimeter surface which corresponds to the shape of the exterior surface of a cross-sectional slice of the bellows, the stacked mold sheets collectively forming a structure, the exterior of which collectively corresponds to the shape of the exterior surface of the bellows;

coating the stacked mold sheets with a coating; and

removing the coating from the stacked mold sheets after the coating has hardened, the removed and hardened coating being the bellows.

15. The method of claim 14 further comprising:

forming a stencil sheet with an opening which corresponds to each unique shape of the perimeter surface of each mold sheet before the stacking;

filling the cavities formed by the openings with a filler before the stacking; and

removing the filler from each mold sheet after it has hardened and before the stacking, the removed and hardened fillers being the mold sheets.

16. The method of claim 15 wherein the stencil sheets are made of PDMS.

17. The method of claim 15 wherein the filer is made of PEG.

18. The method of claim 14 further comprising placing tape on a substrate prior to stacking the mold sheets and wherein the sheets of material are stacked on the tape.

19. The method of claim 14 wherein the coating is Parylene.

20. The method of claim 14 wherein the bellows have a structure which can hold an electrolyte without leakage through the walls of the bellows.

21. The method of claim 14 wherein the method creates bellows which are configured to expand in a direction when inflated and which has folds with surfaces which run substantially perpendicular to the direction of expansion in a collapsed state and which define a stacked set of convolutions, each of which has a collapsed height of no more than 1 mm and a width perpendicular to the direction of expansion of no more than 8 mm.