Osmotically Driven Dispense Pump and Related Components for Use in High Pressure Applications

• US 20080269725A1
• Filed: 07/21/2006
• Published: 10/30/2008
• Est. Priority Date: 07/22/2005
• Status: Active Grant

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Hansen, Bradley C., Ligrani, Phil, Deem, Trent
• Granted Patent: US 9,447,781 B2
• Time in Patent Office: Days
• US Class Current: 604/892.1
• CPC Class Codes: A61K 9/0004 Osmotic delivery systems; Sustained release driven by osmosis, thermal energy or gas
• CPC Class Codes: A61M 2005/14513 with secondary fluid driving or regulating the infusion
• CPC Class Codes: A61M 5/145 using pressurised reservoirs, e.g. pressurised by means of pistons
• CPC Class Codes: F04B 17/00 Pumps characterised by combination with, or adaptation to, specific driving engines or motors

Abstract

A high pressure osmotic dispense pump (10) having a substantially continuous delivery rate and extended delivery times is described and disclosed. The dispense pump (10) includes a semi-permeable membrane (12) which is substantially free of distortions and lateral stretching stresses. The membrane housing (14) and configuration of the present invention allows for consistent and accurate flow rates at the micro-liter level and improved control of the surface area of the semi-permeable membrane (12). This osmotic pump (10) also includes optional methods for activating and deactivating the osmotic process and/or controlling flow rates. Along with these features, the pump can be amplified or modulated to increase the dispense rate and/or adjust the flow rate during operation.

Claims

1. A high pressure osmotic dispense pump, comprising:

a) a semi-permeable membrane which is substantially free of distortions and lateral stretching stresses;

b) a solvent reservoir in fluid communication with the semi-permeable membrane and including a solvent piston which is movable in response to a change in a fluid volume within the solvent reservoir;

c) a solution reservoir in fluid communication with the semi-permeable membrane and including a delivery piston which is movable in response to a change in a fluid volume within the solution reservoir; and

d) a fluid reservoir adjacent the delivery piston opposite the solution reservoir and being fluidly isolated from each of the solvent reservoir and solution reservoir and having an outlet for dispensing a fluid contained in the fluid reservoir.

2. The pump of claim 1, wherein each of the solvent reservoir, solution reservoir, and fluid reservoir have rigid walls.

3. The pump of claim 1, wherein interior surfaces of at least one of the solvent reservoir, solution reservoir, and fluid reservoir include a coating of polytetrafluoroethylene.

4. The pump of claim 1, wherein the pump is configured to deliver the fluid at a flow rate which is substantially continuous.

5. The pump of claim 1, further comprising a spring operatively oriented adjacent the solvent piston opposite the solvent reservoir and configured to displace the solvent piston towards the semi-permeable membrane.

6. The pump of claim 1, wherein the membrane is formed of a material selected from the group consisting of polyamide, porous glass, and cellulose acetate.

7. The pump of claim 1, wherein the solvent piston and the delivery piston are formed of a material selected from the group consisting of polyether ether ketone, polyimide, polycarbonate, glass reinforced polytetrafluoroethylene, and composites or combinations thereof.

8. The pump of claim 1, wherein the semi-permeable membrane has an exposed surface area and a covered surface area, said exposed surface area being smaller than the covered surface area.

9. The pump of claim 1, wherein the semi-permeable membrane is secured by lateral clamping between two members.

10. The pump of claim 1, further comprising a support mesh oriented adjacent the semi-permeable membrane.

11. The pump of claim 1, further comprising a modulator plate oriented between the semi-permeable membrane and the solvent reservoir, said modulator plate having a plurality of holes corresponding to a plurality of delivery flow rates.

12. The pump of claim 1, further comprising a flow activation valve operatively connected between the solvent reservoir and the solution reservoir such that flow of a solvent across the semi-permeable membrane can be selectively controlled.

13. The pump of claim 12, wherein the flow activation valve includes a cylindrical member having an open bore laterally therein such that a central axis of the open bore is substantially perpendicular to a central axis of the cylindrical member.

14. The pump of claim 13, wherein the flow activation valve is oriented between the semi-permeable membrane and the solvent reservoir.

15. The pump of claim 1, further comprising a delivery amplifier operatively connected to the delivery piston, said delivery amplifier having a first portion proximal to the delivery reservoir and a second portion distal to the delivery reservoir, said first portion having a larger cross-section than the second portion.

16. A method of forming a high pressure osmotic dispense pump as in claim 1, comprising:

a) forming a flow channel in at least two membrane housing members wherein the flow channel in each membrane housing member is substantially aligned and forms a fluid connection between a solvent reservoir and a solution reservoir; and

b) securing a semi-permeable membrane between the at least two membrane housing members using substantially only securing forces which are perpendicular to the semi-permeable membrane.

17. The method of claim 16, wherein the step of securing is performed by orienting the semi-permeable membrane between the at least two membrane housing members and inserting at least two alignment members into corresponding alignment channels which are substantially perpendicular to the semi-permeable membrane such that the at least two membrane housing members are pressed towards one another with substantially only forces acting perpendicular to the semi-permeable membrane.

18. The method of claim 16, further comprising the step of coating an interior surface of at least one of the solvent reservoir, solution reservoir, and delivery reservoirs with a low friction material.

19. A method of dispensing a fluid using the pump of claim 1, comprising:

a) charging the solvent reservoir with a solvent which is permeable to the semi-permeable membrane;

b) charging the solution reservoir with a solution of the solvent and a solute, said solution having a concentration of solvent which is lower than a concentration of solvent in the solvent reservoir; and

c) charging the fluid reservoir with a fluid to be dispensed through the outlet.

20. The method of claim 19, wherein the pump is capable of operating at high pressures from about 100 psig to about 300 psig.

21. The method of claim 19, wherein the solvent is water and the solution is aqueous sodium chloride.

22. The method of claim 19, wherein the pump is capable of operating at a temperature up to about 150°

C.