Cannula Assemblies And Ambulatory Infusion Systems With Pressure Sensors Made Of Stacked Coplanar Layers

• US 20100241077A1
• Filed: 03/17/2010
• Published: 09/23/2010
• Est. Priority Date: 03/17/2009
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics International AG (Roche Holding AG)
• Inventors: Geipel, Andreas, Huwiler, Christoph, Haueter, Ulrich, Kuhni, Florian
• Granted Patent: US 8,313,468 B2
• Time in Patent Office: Days
• US Class Current: 604/151
• CPC Class Codes: A61M 2205/0244 Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• CPC Class Codes: A61M 2205/33 Controlling, regulating or measuring
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 5/158 Needles for infusions; Accessories therefor, e.g. for inserting infusion needles, or for holding them on the body
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: G01L 9/0005 using variations in capacitance G01L9/0072 takes precedence
• CPC Class Codes: G01L 9/0041 Transmitting or indicating the displacement of flexible diaphragms

Abstract

Cannula assemblies with pressure sensors made of stacked coplanar layers and ambulatory infusion systems comprising the same are disclosed. The cannula assemblies include a hub and an infusion cannula. The hub includes a pressure sensor and a fluid channel fluidly coupled to the infusion cannula. The pressure sensor is formed from a stack of coplanar layers including a top layer, a base layer an electrode layer and a counter electrode layer. The fluid channel is positioned between the top layer and the base layer. The electrode layer is positioned between the top layer and the base layer and coupled to the fluid channel. The counter-electrode layer is positioned between the top layer and the electrode layer. A spacer layer having a through cut-out defining an electrode cavity is disposed between the top layer and the base layer such that the electrode layer extends across the electrode cavity.

Claims

1. A cannula assembly comprising a hub and an infusion cannula, the hub comprising a pressure sensor and a fluid channel fluidly coupled to the infusion cannula, wherein the pressure sensor comprises a stack of coplanar layers comprising:

a top layer and a base layer, wherein at least a portion of the fluid channel is positioned between the top layer and the base layer;

an electrode layer positioned between the top layer and the base layer and flexibly coupled to the fluid channel;

a counter-electrode layer positioned between the top layer and the electrode layer, the counter electrode layer and electrode layer forming electrodes of a sensing capacitor; and

a first spacer layer comprising a through cut-out defining an electrode cavity disposed between the top layer and the base layer such that the electrode layer extends across the electrode cavity, wherein positive fluidic pressure of a fluid in the fluid channel flexes the electrode layer into the electrode cavity thereby modifying a capacitance of the sensing capacitor.

2. The cannula assembly according to claim 1 further comprising a fluidic coupler in fluid communication with the fluid channel upstream of the pressure sensor, wherein the fluidic coupler is connectable to an infusion device.

3. The cannula assembly according to claim 1, wherein the electrode layer and the first spacer layer are foil.

4. The cannula assembly according to claim 1, wherein the first spacer layer is positioned between and in contact with the electrode layer and the counter-electrode layer and the fluid channel is positioned between the base layer and the electrode layer.

5. The cannula assembly according to claim 4, wherein the electrode layer touches the counter-electrode layer when a maximum threshold pressure in the fluid channel is exceeded.

6. The cannula assembly according to claim 5, wherein the electrode layer and the counter-electrode layer are in galvanic contact when the electrode layer touches the counter-electrode layer.

7. The cannula assembly according to claim 5, wherein at least one of the electrode layer or the counter-electrode layer comprises an insulation layer opposing the other of the electrode layer or the counter-electrode layer such that a galvanic contact is prevented between the electrode layer and the counter-electrode layer when the maximum threshold pressure in the fluid channel is exceeded.

8. The cannula assembly according to claim 1, further comprising a flow restrictor in the fluid channel.

9. The cannula assembly according to claim 1, further comprising a reference capacitor comprising a reference electrode layer and a reference counter-electrode layer.

10. The cannula assembly according to claim 9 wherein:

the first spacer layer is positioned between the reference electrode layer and the reference counter-electrode layer and further comprises a first reference electrode cavity, wherein the first reference electrode cavity is spaced apart from the electrode cavity of the first spacer layer, the reference electrode layer extends across the first reference electrode cavity, and the reference counter-electrode layer extends across the first reference electrode cavity opposite the reference electrode layer; and

the fluid channel is at least partially formed in a fluid channel spacer layer positioned between the base layer and the electrode layer, wherein the reference electrode layer is flexibly coupled to a reference pressure cavity formed in the fluid channel spacer layer and comprising a reference venting aperture.

11. The cannula assembly according to claim 9, wherein either of the electrode layer and the reference electrode layer or the counter-electrode layer and the reference counter-electrode layer are formed as a common layer.

12. The cannula assembly according to claim 1, wherein the fluid channel is flexibly coupled to the counter-electrode layer such that a fluidic pressure of the fluid in the fluid channel flexes the counter-electrode layer and modifies the capacitance of the sensing capacitor.

13. The cannula assembly according to claim 12, wherein:

the first spacer layer is positioned between and in contact with the electrode layer and the counter-electrode layer such that the counter-electrode layer extends across the electrode cavity opposite the electrode layer; and

the fluid channel comprises a first sub-channel positioned between the counter-electrode layer and the top layer and a second sub-channel positioned between the electrode layer and the base layer, wherein positive fluidic pressure in the fluid channel flexes the counter-electrode layer and the electrode layer into the electrode cavity thereby modifying the capacitance of the sensing capacitor.

14. The cannula assembly according to claim 12 further comprising a second spacer layer having an electrode cavity, wherein:

the fluid channel is positioned between the electrode layer and the counter-electrode layer;

the first spacer layer is positioned between the electrode layer and the base layer;

the second spacer layer is positioned between the counter-electrode layer and the top layer, wherein positive fluidic pressure in the fluid channel flexes the electrode layer into the electrode cavity of the first spacer layer and the counter-electrode layer into the electrode cavity of the second spacer layer thereby modifying the capacitance of the sensing capacitor.

15. The cannula assembly according to claim 12, wherein the electrode layer, the counter-electrode layer and the fluid channel are arranged such that the capacitance increases with increasing fluidic pressure of the fluid in the fluid channel.

16. The cannula assembly according to claim 12, wherein the electrode layer, the counter-electrode layer and the fluid channel are arranged such that the capacitance of the sensing capacitor decreases with an increasing fluidic pressure of the fluid in the fluid channel.

17. The cannula assembly according to claim 1, wherein the pressure sensor comprises a secondary sensing capacitor, the secondary sensing capacitor comprising a secondary electrode layer and a secondary counter-electrode layer, wherein the secondary electrode layer, the secondary counter-electrode layer and the fluid channel are arranged such that pressure in the fluid channel modifies the capacitance of the sensing capacitor and the capacitance of the secondary sensing capacitor differently.

18. An ambulatory infusion system for the infusion of a liquid drug into a patient'"'"'s body over an extended time period, the ambulatory infusion system comprising:

a drug container;

an infusion cannula fluidically coupled to the drug container;

an infusion device coupled to the drug container;

a measuring unit; and

a pressure sensor electrically coupled to the measuring unit and fluidically coupled to the drug container and the infusion cannula with a fluid channel, the pressure sensor comprising a stack of coplanar layers comprising;

a top layer and a base layer, wherein at least a portion of the fluid channel is positioned between the top layer and the base layer;

an electrode layer positioned between the top layer and the base layer and flexibly coupled to the fluid channel;

a counter-electrode layer positioned between the top layer and the electrode layer, the counter-electrode layer and the electrode layer forming electrodes of a sensing capacitor; and

a first spacer layer comprising a through cut-out defining an electrode cavity disposed between the top layer and the base layer such that the electrode layer extends across the electrode cavity, wherein positive fluidic pressure in the fluid channel flexes the electrode layer into the electrode cavity thereby modifying a capacitance of the sensing capacitor.

19. The ambulatory infusion system according to claim 18, wherein the first spacer layer is positioned between and in contact with the electrode layer and the counter-electrode layer and the fluid channel is positioned between the base layer and the electrode layer.

20. The ambulatory infusion system according to claim 18, wherein:

the first spacer layer is positioned between and in contact with the electrode layer and the counter-electrode layer such that the counter-electrode layer extends across the electrode cavity opposite the electrode layer; and

the fluid channel comprises a first sub-channel positioned between the counter-electrode layer and the top layer and a second sub-channel positioned between the electrode layer and the base layer, wherein positive fluidic pressure in the fluid channel flexes the counter-electrode layer and the electrode layer into the electrode cavity thereby modifying the capacitance of the sensing capacitor.

21. The ambulatory infusion system according to claim 18 further comprising a second spacer layer having an electrode cavity, wherein:

the fluid channel is positioned between the electrode layer and the counter-electrode layer;

the counter-electrode layer is flexibly coupled to the fluid channel;

the first spacer layer is positioned between the electrode layer and the base layer;

the second spacer layer is positioned between the counter-electrode layer and the top layer, wherein positive fluidic pressure in the fluid channel flexes the electrode layer into the electrode cavity of the first spacer layer and the counter-electrode layer into the electrode cavity of the second spacer layer thereby modifying the capacitance of the sensing capacitor.

22. The ambulatory infusion system according to claim 18, wherein the pressure sensor further comprises a reference capacitor comprising a reference electrode layer and a reference counter-electrode layer.

23. The ambulatory infusion system according to claim 22 wherein:

the first spacer layer is positioned between the reference electrode layer and the reference counter-electrode layer and further comprises a first reference electrode cavity, wherein the first reference electrode cavity is spaced apart from the electrode cavity of the first spacer layer, the reference electrode layer extends across the first reference electrode cavity, and the reference counter-electrode layer extends across the first reference electrode cavity opposite the reference electrode layer; and

the fluid channel is at least partially formed in a fluid channel spacer layer positioned between the base layer and the electrode layer, wherein the reference electrode layer is flexibly coupled to a reference pressure cavity formed in the fluid channel spacer layer and comprising a reference venting aperture.

24. The ambulatory infusion system according to claim 23 wherein the reference electrode layer and the electrode layer are formed as a common layer.

25. The ambulatory infusion system according to claim 18, wherein the pressure sensor comprises a secondary sensing capacitor, the secondary sensing capacitor comprising a secondary electrode layer and a secondary counter-electrode layer, wherein the secondary electrode layer, the secondary counter-electrode layer and the fluid channel are arranged such that pressure in the fluid channel modifies the capacitance of the sensing capacitor and the capacitance of the secondary sensing capacitor differently.