Flow condition sensor assembly for patient infusion device

1. A device for delivering fluid to a patient, comprising:

A) an exit port assembly adapted to connect to a transcutaneous patient access tool;

B) a flow path extending from the exit port assembly; and

C) a flow condition sensor assembly including,

a resilient diaphragm having opposing first and second surfaces, with the first surface positioned against the flow path,

a chamber wall positioned adjacent the second surface of the diaphragm and defining a sensor chamber adjacent the second surface of the diaphragm, and

at least one sensor arranged to provide a threshold signal when the second surface of the diaphragm expands into the chamber in response to at least one predetermined fluid flow condition occurring in the flow path.

2. A device for delivering fluid to a patient, comprising:

A) a flow path extending from the exit port assembly;

B) a flow condition sensor assembly including,

a resilient diaphragm having opposing first and second surfaces, with the first surface positioned against the flow path,

a chamber wall positioned adjacent the second surface of the diaphragm and defining a sensor chamber adjacent the second surface of the diaphragm, and

at least one sensor arranged to provide a threshold signal when the second surface of the diaphragm expands into the chamber by a predetermined amount; and

C) a processor connected to the sensor and programmed to provide a signal indicative of an undesired flow condition upon receiving the threshold signal from the sensor for more than a predetermined maximum period or for less than a predetermined minimum period.

3. A method for determining a fluid flow condition in a flow path, comprising:

positioning a first side of a resilient diaphragm against the flow path;

positioning a chamber wall adjacent a second surface of the diaphragm, the chamber wall defining a sensor chamber adjacent the second surface of the diaphragm;

providing a threshold signal when the second surface of the diaphragm expands into the chamber by a predetermined amount;

timing the duration of the threshold signal; and

providing a signal indicative of a predetermined flow condition if the duration of the threshold signal is greater than a predetermined maximum period or less than a predetermined minimum period.

4. A method according to claim 3 , further comprising activating an alarm upon providing a signal indicative of a predetermined flow condition.

5. A method according to claim 3 , further comprising providing the sensor chamber with a predetermined volume.

6. A method according to claim 3 , further comprising providing the sensor chamber with a predetermined volume and providing a threshold signal when the second surface of the diaphragm contacts the chamber wall.

7. A method according to claim 3 , further comprising providing the flow path with a substantially fixed and predetermined volume.

8. A method according to claim 3 , wherein the predetermined fluid flow condition comprises one of an occlusion in the flow path, and an inadequate flow of fluid in the flow path.

9. A method according to claim 3 , further comprising:

closing the flow path;

causing a volume of fluid at least equal to a volume of the sensor chamber to flow into the fluid path; and

providing a signal indicative of an occlusion test failure if the duration of the threshold signal is less than the predetermined maximum period.

10. A method according to claim 9 , further comprising positioning a second diaphragm against the flow path.

11. A method according to claim 3 , further comprising:

providing pulsitile flow of fluid within the flow path; and

monitoring the threshold signals between pulses of fluid.