Methods and devices for determination of flow reservoir volume

• US 8,573,027 B2
• Filed: 02/26/2010
• Issued: 11/05/2013
• Est. Priority Date: 02/27/2009
• Status: Active Grant

• Current Assignee: Tandem Diabetes Care Incorporated
• Original Assignee: Tandem Diabetes Care Incorporated
• Inventors: Rosinko, Michael J., DiPerna, Paul M.
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): WEST, PAUL M
• Application Number:
  US12/714,299
• Publication Number:
  US 20100218586A1
• Time in Patent Office: 1,348 Days
• Field of Search: 73/13.5, 73/13.6
• US Class Current: 73/1.35
• CPC Class Codes: G01F 11/08 of the diaphragm or bellows type

Abstract

A novel enhanced flow metering device is adapted for disposing into a flow material reservoir a known volume of flow material whereby software used in conjunction with a pressure sensor may be calibrated. Additionally, by measuring the known amount of flow material returning to the flow material reservoir, checks are quickly made to ensure the pressure sensor is behaving as expected.

Claims

1. A method of completing a metering cycle, comprising:

positioning an actuation shaft of a flow metering device in a first position in a cavity for filling a flow metering device chamber in fluid communication with the cavity with a flow material;

causing an aliquot of flow material to flow into the flow metering device chamber from a flow material reservoir through an input conduit and a proximal flow space defined by the cavity;

positioning the actuation shaft in a second position in the cavity for dispensing the flow material from the flow metering device chamber, wherein the flow material reservoir is in fluid communication with the proximal flow space when the actuation shaft is in the second position such that the positioning of the actuation shaft to the second position causes a backstroke volume of flow material to flow from the proximal flow space into the flow material reservoir;

observing the change in volume of the flow material in the flow material reservoir with data gathered from a sensor; and

determining the backstroke volume.

2. The method of claim 1, wherein the data gathered from the sensor is gathered before positioning the actuation shaft in the second position and after positioning the actuation shaft in the second position.

3. The method of claim 1, wherein the determination of the backstroke volume comprises measuring the difference of the volume of the flow material in the flow material reservoir before positioning the actuation shaft in the second position and the volume of the flow material in the flow material reservoir after positioning the actuation shaft in the second position.

4. The method of claim 1, wherein the sensor is a pressure sensor.

5. A method of completing a metering cycle, comprising:

positioning an actuation shaft of a flow metering device in a first position for filling a flow metering device chamber with a flow material;

causing an aliquot of flow material to flow into the flow metering device chamber from a flow material reservoir through an input conduit and a proximal flow space;

positioning the actuation shaft in a second position for dispensing the flow material from the flow metering device chamber, wherein the positioning of the actuation shaft to the second position causes a backstroke volume of flow material to flow from the proximal flow space into the flow material reservoir;

observing the change in volume of the flow material in the flow material reservoir with data gathered from a sensor; and

determining the backstroke volume,

wherein the determination of the backstroke volume comprises measuring the difference of the volume of the flow material in the flow material reservoir before positioning the actuation shaft in the second position and the volume of the flow material in the flow material reservoir after positioning the actuation shaft in the second position, and

wherein the flow material reservoir comprises a first chamber holding the flow material and a second chamber holding a gas and the sensor.

6. A method of completing a metering cycle, comprising:

positioning an actuation shaft of a flow metering device a first position for filling a flow metering device chamber with a flow material;

causing an aliquot of flow material to flow into the flow metering device chamber from a flow material reservoir through an input conduit and a proximal flow space;

positioning the actuation shaft in a second position for dispensing the flow material from the flow metering device chamber, wherein the positioning of the actuation shaft to the second position causes a backstroke volume of flow material to flow from the proximal flow space into the flow material reservoir;

observing the change in volume of the flow material in the flow material reservoir with data gathered from a sensor; and

determining the backstroke volume,

wherein if a first determined backstroke volume is not substantially the same as a second backstroke volume, then movement of the actuation shaft is stopped.

7. A method of completing a metering cycle, comprising:

positioning an actuation shaft of a flow metering device in a first position for filling a flow metering device chamber with a flow material;

causing an aliquot of flow material to flow into the flow metering device chamber from a flow material reservoir through an input conduit and a proximal flow space;

positioning the actuation shaft in a second position for dispensing the flow material from the flow metering device chamber, wherein the positioning of the actuation shaft to the second position causes a backstroke volume of flow material to flow from the proximal flow space into the flow material reservoir;

observing the change in volume of the flow material in the flow material reservoir with data gathered from a sensor; and

determining the backstroke volume,

wherein if a first determined backstroke volume is not about equal to a second backstroke volume, then an error state is triggered in the flow metering device or pump.

8. A method comprising:

providing a flow metering device system adapted for use with a pump having a flow material reservoir and configured to measure the volume of the flow material in the flow material reservoir,

the flow metering device system adapted to completing a plurality of metering cycles, each cycle comprising;

positioning an actuation shaft of a flow metering device in a first position for filling a flow metering device chamber with a flow material;

causing an aliquot of flow material to flow into the flow metering device chamber from a flow material reservoir through an input conduit and a proximal flow space;

positioning the actuation shaft in a second position for dispensing the flow material from the flow metering device chamber, wherein the positioning of the actuation shaft to the second position causes a backstroke volume of flow material to flow from the proximal flow space into the flow material reservoir; and

calculating the volume of the flow material in the flow material reservoir using a sensor and the backstroke volume.

9. The method of claim 8, wherein the determination of the backstroke volume comprises measuring difference of the volume of the flow material in the flow material reservoir before positioning the actuation shaft in the second position and the volume of the flow material in the flow material reservoir after positioning the actuation shaft in the second position.

10. The method of claim 9, wherein the flow material reservoir comprises a first chamber holding the flow material and a second chamber holding a gas and the sensor.

11. The method of claim 8, wherein the sensor is a pressure sensor.

12. The method of claim 8, wherein if a first determined backstroke volume is not substantially the same as a second backstroke volume, then movement of the actuation shaft is stopped.

13. The method of claim 8, wherein if a first determined backstroke volume is not about equal to a second backstroke volume, then an error state is triggered in the flow metering device or pump.

14. A method of determining a backstroke volume comprising:

coupling a proximal flow space with a flow material reservoir of known volume and having a known volume of fluid disposed therein and using a sensor to gather data relevant to determination of the volume of the fluid in the flow material reservoir prior to moving an actuation shaft (V_t);

causing an aliquot of fluid to move from the flow material reservoir to the proximal flow space by moving the actuation shaft to a filling position;

using the sensor to gather data relevant to determination of the volume of the fluid in the flow material reservoir when the actuation shaft is in the filling position (V_f);

moving the actuation to a dispense position, whereby a backstroke fluid volume moves from the proximal flow space into the flow material reservoir; and

using the sensor to gather data relevant to determination of the volume of the fluid in the flow material reservoir when the actuation shaft is in the dispense position (V_b);

calculating the backstroke fluid volume from the data collected from the sensor.

15. The method of claim 14, wherein the sensor comprises a pressure transducer.

16. The method of claim 15, wherein the calculation comprises:

calculating V_f according to the following equation;

17. A method for calibrating offset of a sensor comprising:

configuring a flow metering system having at least as flow metering device and flow material reservoir, wherein a flow material reservoir in the system has a known total volume and a known volume of flow material in the flow material reservoir;

determining a backstroke volume of a flow metering device, the backstroke volume comprising a volume of flow material moved from a proximal flow space of the flow metering device into the flow material reservoir when an actuation shaft is moved to a dispense position;

using the sensor to gather data relevant to determination of the volume of the flow material in the flow material reservoir when the actuation shaft is in the filling position (V_f);

using the sensor to gather data relevant to determination of the volume of the flow material in the flow material reservoir when the actuation shaft is in the dispense position (V_b);

using the data gathered by the sensor and the backstroke volume data to determine the offset of the sensor;

calibrating the sensor by accounting for the offset of the sensor in subsequent use of the sensor to gather data.

18. The method of claim 17, wherein the flow metering system further comprises a pump that houses the flow material reservoir and wherein the pump houses the sensor.

19. The method of claim 17, wherein the flow material reservoir comprises a first chamber holding the flow material and a second chamber holding a gas and the sensor.

20. The method of claim 17, wherein the flow material reservoir comprises a gas chamber having a sensor and a flow material chamber, wherein as the volume of one chamber increases, the volume of the other chamber decreases by the same volume.