MEMS FLUID PUMP WITH INTEGRATED PRESSURE SENSOR FOR DYSFUNCTION DETECTION

• US 20110142688A1
• Filed: 10/22/2008
• Published: 06/16/2011
• Est. Priority Date: 10/22/2008
• Status: Active Grant

• Current Assignee: Debiotech S.A.
• Original Assignee: Debiotech S.A.
• Inventors: Neftel, Frederic, Schneeberger, Niklaus, Chappel, Eric
• Granted Patent: US 9,192,720 B2
• Time in Patent Office: Days
• US Class Current: 417/213
• CPC Class Codes: A61M 2005/16863 Occlusion detection
• CPC Class Codes: A61M 2005/16868 Downstream occlusion sensors
• CPC Class Codes: A61M 2205/0244 Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• CPC Class Codes: A61M 2205/0294 Piezoelectric materials
• CPC Class Codes: A61M 2205/3355 Controlling downstream pump pressure
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 5/14224 Diaphragm type
• CPC Class Codes: A61M 5/168 Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body flow control in general G05D7/00
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations

Abstract

The invention relates to a pumping device including a pump (1) comprising—a pumping chamber (11) having a variable volume,—an inlet (2) communicating with the pumping chamber (11) and comprising a valve,—an outlet (5) communicating with the pumping chamber and comprising a valve,—an actuator adapted to change the volume of the pumping chamber,—a fluidic pathway comprising said inlet (2), said pumping chamber (11), said outlet (5) and a downstream line (7) situated downstream of the outlet valve,—a pressure sensor (4) for measuring the pressure between the valves of said pathway,—processing means for processing the received pressure data from the pressure sensor (4). The invention also covers a method for detecting a dysfunction in a pumping device as defined above.

Claims

1. Pumping device including a pump (1) comprising

a pumping chamber (11) having a variable volume,

an inlet (2) communicating with the pumping chamber (11) and comprising a valve,

an outlet (5) communicating with the pumping chamber and comprising a valve,

an actuator adapted to change the volume of the pumping chamber,

a fluidic pathway comprising said inlet (2), said pumping chamber (11), said outlet (5) and a downstream line (7) situated downstream of the outlet valve,

a pressure sensor (4) for measuring the pressure between the valves of said pathway,

processing means for processing the received pressure data from the pressure sensor (4).

2. Pumping device according to claim 1 wherein the pressure sensor (4) is structurally adapted to be used for detecting occlusions in the downstream line (7).

3. Pumping device according to claim 1 wherein the pump is a micro pump with the volume of the pumping chamber (11) comprised between 10 nl and 100 μ

l.

4. Pumping device according to claim 1 comprising a pumping membrane (3), functionally linked to said actuator, which is adapted to change the volume of said pumping chamber (11) and wherein at least one said valves is a check valve.

5. Pumping device according to claim 1 wherein at least one valve includes pretension means that are activated at least during operation of part of the pumping cycle.

6. Pumping device according to claim 1 wherein at least one valve can be further externally controlled.

7. Pumping device according to claim 1 wherein the pressure sensor (4) comprises a flexible membrane.

8. Pumping device according to claim 4 wherein the pumping membrane (3) is made of a semiconductor material, and wherein a strain gauge is implanted or diffused onto the membrane (3).

9. Pumping device according to claim 4 comprising an optical sensor which is adapted to monitor the deflection of the pumping membrane (3).

10. Pumping device according to claim 9 comprising an astigmatic optical element between the pumping membrane (3) and the optical sensor.

11. Pumping device according to claim 1, comprising at least one further pressure sensor.

12. Pumping device according to claim 11 wherein said further pressure sensor is positioned in the downstream line.

13. Pumping device according to claim 1 comprising a flow restrictor in the downstream line.

14. Pumping device according to claim 11 wherein said further pressure sensor is positioned between the outlet valve and the flow restrictor.

15. Pumping device according to claim 1 furthermore comprising a temperature sensor.

16. Method for detecting at least one dysfunction in an infusion assembly which includes a pumping device as defined in claim 1, the method comprising the measurement of the pressure in the fluidic pathway during pumping, the processing of the resulting pressure values and the provision of a functioning status based on the processed pressure values.

17. Method according to claim 16 for a pumping mechanism which is achieved through repetition of pumping cycles;

each of said pumping cycle including at least one suction phase during which the volume of the pumping chamber is increased and the pressure is thus decreased, and also at least one discharge phase during which the volume of the chamber is decreased and the pressure is thus increased;

the pumping chamber volume returning to its initial size at the end of the cycle.

18. Method according to claim 17 wherein each of said pumping cycle further includes at least one stationary phase, after the discharge phase and/or after the suction phase, during which the volume of the pumping chamber does not change, both valves being closed and the pressure in the pumping chamber is thus essentially constant but differs from the pressure at the inlet or at the outlet.

19. Method according to claim 16 wherein the dynamic pressure is measured during each phase of a pumping cycle.

20. Method according to claim 16 for detecting at least one of the following dysfunctions:

Occlusion, leakage, air bubbles, bad connection, pumping non-accuracy, malfunction of the actuator, emptying of a drug reservoir.

21. Method according to claim 16 wherein the processing of the resulting pressure values includes a comparison between the measured pressure values among each others and/or reference pressure values.

22. Method according to claim 16 including the determination of at least one of the pressure change, the maximum pressure, and/or the minimum pressure during at least one phase of a pumping cycle.

23. Method according to claim 16 including the determination of the time to achieve a predefined pressure during a pumping cycle.

24. Method according to claim 18 for detecting at least one of the following dysfunctions during at least one stationary phase:

leakage, bad connection and pumping non-accuracy by measuring the rate of pressure change.

25. Method according to claim 24 wherein leakage, bad connection and/or pumping non-accuracy is detected when at least two measured pressure values of the stationary phase after the discharge and the suction phases become equal.

26. Method according to claim 16 for detecting downstream occlusions by measuring the maximum pressure during the discharge phase.

27. Method according to claim 18 wherein an occlusion is detected if the value of the pressure during the stationary phase after the discharge phase is not decreased, at least by a certain percentage or value, with respect to the maximum pressure during the discharge phase.

28. Method according to claim 16 for detection of air in the pump device by measuring the pressure at least during one discharge phase and/or one suction phase.

29. Method according to claim 28 wherein air in the pump is detected if a pressure response during the compression and/or depression cycle shows a substantially lower peak and/or wider peak than a normalized pressure response.

30. Method according to claim 16 including a leak test which is enhanced by generating a high pressure in the pumping chamber, e.g. by closing the outlet valve by external means and by compressing the volume in the pumping chamber.

31. Method according to claim 30 wherein after creating an overpressure in the pumping chamber, a maximum of pressure and a pressure decay are monitored for detecting leakage rate, compression ratio and/or self-priming capability of the pump, valve pretensions, malfunction of the actuator and/or stroke volume.

32. Method according to claim 16 for measuring the pulsed flow rate of a pumping device, said method comprising the measurement of the pressure in the downstream line using constant sampling intervals and the processing of the resulting pressure values.

33. Method according to claim 16 for detecting, by using jointly a pressure sensor in the pump and a pressure sensor in the downstream lime, at least one of the following parameters:

Flow rate, occlusion, leakage, air bubbles, bad connection, pumping non-accuracy, malfunction of the actuator.

34. Method according to claim 33 for furthermore measuring the leak rate of the valve located between the pressure sensor in the pump and the further pressure sensor in the downstream line, the method comprising the measurement of the pressures downstream and upstream of said outlet valve and a comparison between the measured pressure values among each others and/or according to reference pressure values.