Fluid delivery system and method

• US 6,932,114 B2
• Filed: 02/24/2003
• Issued: 08/23/2005
• Est. Priority Date: 02/22/2002
• Status: Active Grant

• Current Assignee: Integrated Sensing Systems Incorporated
• Original Assignee: Integrated Sensing Systems Incorporated
• Inventors: Sparks, Douglas Ray
• Primary Examiner(s): Sirmons, Kevin C.
• Application Number:
  US10/248,839
• Publication Number:
  US 20030159741A1
• Time in Patent Office: 911 Days
• Field of Search: 137/814, 604/65, 604/131, 604247-249, 604/67, 604/246, 738/61, 733/52, 731/182
• US Class Current: 137/814
• CPC Class Codes: A61M 2205/0244 Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/16827 controlling delivery of multiple fluids, e.g. sequencing, mixing or via separate flow-paths infusion of multiple fluids without using a controller A61M5/1407
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: G01F 1/8445 micromachined flowmeters
• CPC Class Codes: G01F 1/8472 having curved measuring conduits, i.e. whereby the measuring conduits' curved center line lies within a plane G01F1/8481 takes precedence
• CPC Class Codes: G01F 13/006 measuring volume in function of time
• CPC Class Codes: Y10T 137/212 System comprising plural fluidic devices or stages

Abstract

A fluid delivery system capable of delivering a precise amount of fluid and monitor certain properties of the fluid so that the correct fluid is safely delivered to its intended destination. The system makes use of a flow sensor comprising a freestanding tube portion vibrated at a resonant frequency, wherein the resonant frequency corresponds to the density of the fluid flowing through the tube portion and the tube portion exhibits a degree of twist that varies with the mass flow rate of the fluid flowing therethrough. Movement of the tube portion is then sensed to produce a first output signal corresponding to the fluid density and a second output signal corresponding to the mass flow rate. The system is also equipped to measure elapsed time and to stop fluid flow in response to either of the first and second output signals.

Claims

1. A fluid delivery system having a fluid-handling unit comprising:

a tube adapted for receiving a fluid from a fluid source, the tube comprising a freestanding tube portion through which the fluid flows;

means for vibrating the freestanding tube portion of the tube at a resonant frequency thereof that varies with the density of the fluid flowing therethrough, the Coriolis effect causing the freestanding tube portion to twist while being vibrated at resonance, the freestanding tube portion exhibiting a degree of twist that varies with the mass flow rate of the fluid flowing therethrough;

means for sensing movement of the freestanding tube portion of the tube, the movement-sensing means producing a first output signal based on the resonant frequency of the freestanding tube portion and a second output signal based on the degree of twist of the freestanding tube portion;

means for setting a range for the first output signal corresponding to a range for the density of the fluid; and

means for stopping flow of the fluid through the fluid handling unit in response to the first output signal from the movement-sensing means, wherein the flow-stopping means, the movement-sensing means, and the range-setting means cooperate to stop the flow of the fluid through the fluid handling unit if the density of the fluid is outside the range therefor set with the range-setting means.

2. The fluid delivery system according to claim 1, wherein the flow-stopping means stops the flow of the fluid if, based on the first output signal, the density of the fluid is outside the range therefor because the fluid contains bubbles.

3. The fluid delivery system according to claim 1, further comprising means for sounding an alarm if, based on the first output signal, the density of the fluid is outside the range therefor set with the range-setting means.

4. The fluid delivery system according to claim 1, further comprising at least a second flow sensor through which a second fluid flows, and means for stopping flow of the second fluid through the second flow sensor.

5. The fluid delivery system according to claim 1, further comprising a pumping means for delivering the fluid to the fluid handling unit, a flow sensor between the pumping means and the fluid handling unit, and a valve between the pumping means and the flow sensor, the flow sensor comprising:

a second freestanding tube portion through which the fluid flows after being received from the pumping means;

means for vibrating the second freestanding tube portion at a resonant frequency thereof that varies with the density of the fluid flowing therethrough;

the Coriolis effect causing the second freestanding tube portion to twist while being vibrated at resonance, the second freestanding tube portion exhibiting a degree of twist that varies with the mass flow rate of the fluid flowing therethrough;

means for sensing movement of the second freestanding tube portion, the movement-sensing means producing a first output signal based on the resonant frequency of the second freestanding tube portion and a second output signal based on the degree of twist of the second freestanding tube portion;

means for measuring elapsed time during which the fluid has flowed through the flow sensor; and

means for stopping flow of the fluid through the flow sensor in response to either of the first and second output signals from the movement-sensing means of the flow sensor.

6. The fluid delivery system according to claim 5, wherein the pumping means serves as a reservoir for the fluid prior to the pumping means delivering the fluid to the flow sensor.

7. The fluid delivery system according to claim 5, wherein the fluid passage is a tube for intravenous, intra-arterial, subcutaneous, intramuscular, intraperitoneal or intrathecal delivery of the fluid.

8. The fluid delivery system according to claim 1, wherein the flow-stopping means is a valve.

9. The fluid delivery system according to claim 1, wherein the fluid deliver system comprises a plurality of the fluid handling units arranged in fluidic parallel to deliver at least the fluid to a fluid passage.

10. The fluid delivery system according to claim 9, wherein at least one of the fluid handling units delivers a different second fluid to the fluid passage.

11. The fluid delivery system according to claim 1, wherein the fluid handling unit is implanted in a living subject, the fluid delivery system further comprising a sensor implanted in the living subject and in communication with the fluid handling unit for dispensing the fluid to the living subject.

12. An infusion system comprising:

a first flow sensor that receives a first fluid from a first fluid source and delivers the first fluid to a tube attached to a human subject, the first flow sensor comprising a first freestanding tube portion through which the first fluid flows, first means for vibrating the first freestanding tube portion at a resonant frequency thereof that varies with the density of the first fluid flowing therethrough, first means for sensing movement of the first freestanding tube portion, the first movement-sensing means producing a first output signal based on the resonant frequency of the first freestanding tube portion and a second output signal based on the degree of twist of the first freestanding tube portion, the Coriolis effect causing the first freestanding tube portion to twist while being vibrated at resonance, the first freestanding tube portion exhibiting a degree of twist that varies with the mass flow rate of the first fluid flowing therethrough;

a plurality of second flow sensors arranged in fluidic parallel, the second flow sensors delivering at least a second fluid from at least a second fluid source to the tube, each of the second flow sensors comprising a second freestanding tube portion through which the second fluid flows, second means for vibrating the second freestanding tube portion at a resonant frequency thereof that varies with the density of the second fluid flowing therethrough, second means for sensing movement of the second freestanding tube portion, the second movement-sensing means producing a first output signal based on the resonant frequency of the second freestanding tube portion and a second output signal based on the degree of twist of the second freestanding tube portion, the Coriolis effect causing the second freestanding tube portion to twist while being vibrated at resonance, the second freestanding tube portion exhibiting a degree of twist that varies with the mass flow rate of the second fluid flowing therethrough;

means for measuring elapsed time during which the first and second fluids have flowed through the first and second flow sensors; and

means for stopping flow of the first and second fluids through the first and second flow sensors, respectively, in response to either of the first and second output signals from the first and second movement-sensing means, wherein the flow-stopping means is operable to stop the flow of the second fluid if, based on the elapsed time determined by the time-measuring means and the second output signal of the second movement-sensing means, a specified amount of the second fluid has passed through any one or more of the second flow sensors.

13. The infusion system according to claim 12, wherein the flow-stopping means stops the flow of the second fluid if, based on the first output signal of the second flow sensor, the resonant frequency of the second freestanding tube portion is outside a range specified for the second fluid.

14. The infusion system according to claim 12, wherein the first and second movement-sensing means are effect to sense that the resonant frequencies of the first and second fluids are outside ranges specified therefor if either of the first and second fluids contains gas bubbles.

15. The infusion system according to claim 12, further comprising a pumping means for delivering the first fluid from the first fluid source to the first flow sensor.

16. The infusion system according to claim 15, wherein the pumping means serves as a reservoir for the specified amount of the fluid prior to the pumping means delivering the first fluid to the first flow sensor.

17. A fluid delivery method comprising the steps of:

flowing a fluid through a freestanding tube portion;

vibrating the freestanding tube portion at a resonant frequency thereof that varies with the density of the fluid flowing therethrough, the Coriolis effect causing the freestanding tube portion to twist while being vibrated at resonance, the freestanding tube portion exhibiting a degree of twist that varies with the mass flow rate of the fluid flowing therethrough;

sensing movement of the freestanding tube portion and producing a first output signal based on the resonant frequency of the freestanding tube portion and a second output signal based on the degree of twist of the freestanding tube portion;

measuring elapsed time during which the fluid has flowed through the freestanding tube portion; and

stopping flow of the fluid through the freestanding tube portion in response to either of the first and second output signals, wherein flow of the fluid is stopped if, based on the elapsed time and the second output signal, a specified amount of the fluid has passed through the freestanding tube portion.

18. The fluid delivery method according to claim 17, wherein flow of the fluid is stopped if, based on the first output signal, the resonant frequency is outside a range specified for the fluid.

19. The fluid delivery method according to claim 18, further comprising the step of sounding an alarm if, based on the first output signal, the resonant frequency is outside a range specified for the fluid.

20. The fluid delivery method according to claim 17, further comprising the step of delivering the specified amount of the fluid from the freestanding tube portion to a fluid passage.

21. The fluid delivery method according to claim 20, wherein a pump serves as a reservoir for the fluid prior to the pump delivering the fluid to the freestanding tube portion.

22. The fluid delivery method according to claim 20, wherein the fluid passage is a tube for intravenous, intra-arterial, subcutaneous, intramuscular, intraperitoneal or intrathecal delivery of the fluid.

23. The fluid delivery method according to claim 17, wherein a valve stops the flow of fluid.

24. The fluid delivery method according to claim 17, wherein the fluid deliver method utilizes a plurality of the freestanding tube portions arranged in fluidic parallel to deliver at least the fluid to a fluid passage.

25. The fluid delivery method according to claim 24, wherein at least one of the freestanding tube portions delivers a different second fluid to the fluid passage.

26. An infusion method comprising the steps of:

flowing a first fluid from a first fluid source through a first flow sensor to a tube attached to a human subject, the first flow sensor comprising a first freestanding tube portion through which the first fluid flows, first means for vibrating the first freestanding tube portion at a resonant frequency thereof that varies with the density of the first fluid flowing therethrough, first means for sensing movement of the first freestanding tube portion, the first movement-sensing means producing a first output signal based on the resonant frequency of the first freestanding tube portion and a second output signal based on the degree of twist of the first freestanding tube portion, the Coriolis effect causing the first freestanding tube portion to twist while being vibrated at resonance, the first freestanding tube portion exhibiting a degree of twist that vanes with the mass flow rate of the first fluid flowing therethrough;

flowing a second fluid from a second fluid source through a second flow sensor to the tube, the second flow sensor comprising a second freestanding tube portion through which the second fluid flows, second means for vibrating the second freestanding tube portion at a resonant frequency thereof that varies with the density of the second fluid flowing therethrough, second means for sensing movement of the second freestanding tube portion, the second movement-sensing means producing a first output signal based on the resonant frequency of the second freestanding tube portion and a second output signal based on the degree of twist of the second freestanding tube portion, the Coriolis effect causing the second freestanding tube portion to twist while being vibrated at resonance, the second freestanding tube portion exhibiting a degree of twist that varies with the mass flow rate of the second fluid flowing therethrough;

measuring elapsed time during which the first and second fluids have flowed through the first and second flow sensors, respectively; and

stopping flow of the first and second fluids through the first and second flow sensors, respectively, in response to either of the first and second output signals from the first and second movement-sensing means, wherein the flow of the second fluid is stopped if, based on the elapsed time determined by the time-measuring means and the second output signal of the second movement-sensing means, a specified amount of the second fluid has passed through the second flow sensor.

27. The infusion method according to claim 26, wherein the flow of the second fluid is stopped if, based on the first output signal of the second flow sensor, the resonant frequency of the second freestanding tube portion is outside a range specified for the second fluid.

28. The infusion method according to claim 27, wherein the resonant frequency is outside the range specified for the second fluid as a result of the second fluid containing gas bubbles.

29. The infusion method according to claim 26, wherein a pump serves as a reservoir for delivering the first fluid from the first fluid source to the first flow sensor.

30. The infusion method according to claim 26, wherein the infusion method utilizes a plurality of the second flow sensors arranged in fluidic parallel to deliver at least the second fluid to the tube.