Miniature pump for drug delivery

1. An infusion device for use in delivering drugs, the device comprising:

a) a housing having a chamber, the housing having an outlet;

b) a diaphragm operatively connected to the housing, the diaphragm dividing the chamber into a drug storage subchamber and a propellant subchamber, the diaphragm constructed from a shape memory alloy material, the diaphragm is configured to go over center for greater volume efficiencies;

c) the propellant subchamber adapted and configured to receive a suitable propellant;

d) the shape memory alloy selected for low bending stresses, wherein significant pressure changes are not imparted to the drug storage subchamber; and

e) the drug storage subchamber adapted and configured to receive a suitable drug, the drug storage subchamber having an outlet in fluid communication with the outlet of the housing.

2. The infusion device of claim 1 , further comprising a septum operatively connected to the housing and in fluid communication with the drug storage subchamber.

3. The infusion device of claim 1 , wherein the diaphragm is constructed from a Ni—Ti alloy.

4. The infusion device of claim 1 , further comprising a flow restrictor having a first end in fluid communication with the outlet of the drug storage subchamber and a second end in fluid communication with the housing outlet.

5. The infusion device of claim 4 , the flow restrictor being a micro-machined flow resistor.

6. The infusion device of claim 5 , the micro-machined flow resistor comprising:

a) a first substrate member having a planar top surface;

b) a second substrate member having a planar bottom surface, the bottom surface of the second substrate member positioned on the top surface of the first substrate member to form a chip assembly;

c) one of the top surface and bottom surface having a channel machined thereon; and

d) the chip assembly having an inlet in fluid communication with the drug storage subchamber outlet and an outlet in fluid communication with the housing outlet.

7. The infusion device of claim 6 , wherein the first and second substrates are glass substrates.

8. The infusion device of claim 6 , wherein the channel is sized for a flow rate of approximately 1 ml per month.

9. The infusion device of claim 6 , wherein the channel is 0.02 mm in width±200 nm and a depth of 0.005 mm±50 nm.

10. The infusion device of claim 5 , wherein the pump is a fixed rate pump.

11. The infusion device of claim 1 , wherein the drug reservoir, when fully dispensed, dispenses at least 90% of the drug reservoir, when full.

12. The infusion device of claim 1 , wherein the shape memory alloy is a Ni—Ti alloy.

13. The infusion device of claim 12 , wherein the Ni—Ti alloy is superelastic.

14. The infusion device of claim 12 , wherein the Ni—Ti alloy is superdeformable.

15. The infusion device of claim 1 , wherein the infusion device is an implantable infusion device.

16. An infusion device for use in delivering drugs, the device comprising:)

a housing having a chamber, the housing having an outlet;

b) a diaphragm operatively connected to the housing, the diaphragm dividing the chamber into a drug storage subchamber and a propellant subchamber, the diaphragm constructed from a shape memory alloy, the diaphragm is configured to go over center for greater volume efficiencies;

c) the propellant subchamber adapted and configured to receive a suitable propellant;

d) the shape memory alloy selected for low bending stresses, wherein significant pressure changes are not imparted to the drug storage subchamber;

e) the drug storage subchamber adapted and configured to receive a suitable drug, the drug storage subchamber having an outlet in fluid communication with the outlet of the housing; and

f) a flow restrictor having a first end in fluid communication with the outlet of the drug storage subchamber and a second end in fluid communication with the housing outlet, the flow restrictor being a micro-machined flow restrictor, the flow restrictor comprising:

i) a first glass member having a planar top surface;

ii) a second glass member having a planar bottom surface, the bottom surface of the second glass member positioned on the top surface of the first glass member to form a chip assembly;

iii) one of the top surface and bottom surface having a channel machined thereon; and

iv) the chip assembly having an inlet in fluid communication with the drug storage subchamber outlet and an outlet in fluid communication with the housing outlet.

17. The infusion device of claim 16 , wherein the shape memory alloy is a Ni—Ti alloy.

18. The infusion device of claim 16 , wherein the infusion device is implantable.

19. The infusion device of claim 3 , wherein the Ni—Ti alloy is in an Austenitic phase wherein the Ni—Ti alloy provides for superelastic properties to accommodate bending.

20. The infusion device of claim 3 , wherein the Ni—Ti alloy is in a Martensitic phase wherein the Ni—Ti alloy provides for superelastic properties to provide for an ability to undergo large strains and deformation without fracture.

21. The infusion device of claim 17 , wherein the Ni—Ti alloy is in an Austenitic phase wherein the Ni—Ti alloy provides for superelastic properties to accommodate bending.

22. The infusion device of claim 17 , wherein the Ni—Ti alloy is in a Martensitic phase wherein the Ni—Ti alloy provides for superdeformable properties to provide for an ability to undergo large strains and defoiiiiation without fracture.