Occlusion detection for a fluid infusion device
A device for delivering fluid to a user includes a housing, a drive motor assembly in the housing, a force sensor, and an electronics module. The drive motor assembly regulates delivery of fluid by actuating a piston of a fluid reservoir, and the force sensor generates output levels in response to force imparted thereto during, for example, fluid delivery operations. The electronics module processes the output levels of the force sensor to assess the operating health of the force sensor, to check for occlusions in the fluid delivery path, and to monitor the seating status of the fluid reservoir.
1. A device for delivering fluid to a user, the device comprising:
a housing;
a reservoir cavity within the housing to accommodate fluid reservoirs;
a drive motor assembly in the housing to regulate delivery of fluid by actuating a piston of a fluid reservoir;
a force sensor associated with the drive motor assembly to generate output levels in response to force imparted thereto; and
an electronics module coupled to the force sensor to process the output levels to detect occlusions in a fluid path of the device for a fluid delivery action by:
indicating an occlusion when a first rate of change of the output levels is greater than or equal to a first threshold value, the first rate of change based upon a first measurement window; and
indicating an occlusion when both: (a) a second rate of change of the output levels is greater than or equal to a second threshold value, the second rate of change based upon a second measurement window; and (b) a current output level is greater than or equal to a threshold output level.
2. The device of claim 1 , wherein each of the output levels represents a measure of actuation force imparted to the force sensor during the fluid delivery action.
3. The device of claim 1 , wherein each of the output levels has an associated quantity measurement.
4. The device of claim 3 , wherein each quantity measurement is a delivered volume of fluid relative to a reference volume of fluid.
5. The device of claim 1 , wherein the first measurement window and the second measurement window represent a volume of fluid dispensed from the fluid reservoir relative to a reference volume measurement.
6. The device of claim 1 , wherein the first measurement window is different than the second measurement window.
7. The device of claim 1 , wherein:
the electronics module determines, for each of a plurality of measurement points during the fluid delivery action, a respective output level, along with a respective delivered volume measurement relative to a reference volume measurement; and
the electronics module calculates the first rate of change of the output levels based upon the current output level, a previous output level, a current delivered volume measurement corresponding to the current output level, and a previous delivered volume measurement corresponding to the previous output level.
8. The device of claim 7 , wherein:
the electronics module calculates the second rate of change based upon the current output level, an intervening output level that is determined after determining the previous output level, the current delivered volume measurement, and an intervening delivered volume measurement corresponding to the intervening output level.
9. The device of claim 1 , wherein the first threshold value is greater than the second threshold value.
10. The device of claim 1 , wherein the electronics module initiates corrective action for the fluid infusion device when an occlusion is detected.
11. A device for delivering fluid to a user, the device comprising:
a housing;
a reservoir cavity within the housing to accommodate a fluid reservoir;
a drive motor assembly in the housing to regulate delivery of fluid by actuating a piston of the fluid reservoir;
a force sensor associated with the drive motor assembly to generate output levels in response to force imparted thereto; and
an electronics module coupled to the force sensor to process the output levels to detect occlusions in a fluid path of the device for a fluid delivery action by:
indicating an occlusion when a first rate of change of the output levels is greater than or equal to a first threshold value, the first rate of change based upon a first measurement window; and
indicating an occlusion when both: (a) a second rate of change of the output levels is greater than or equal to a second threshold value, the second rate of change based upon a second measurement window; and (b) a current output level is greater than or equal to a threshold output level,
wherein the first measurement window and the second measurement window represent a volume of fluid dispensed from the fluid reservoir relative to a reference volume measurement.
12. The device of claim 11 , wherein the first measurement window is greater than the second measurement window.
13. The device of claim 11 , wherein:
the electronics module determines, for each of a plurality of measurement points during the fluid delivery action, a respective output level, along with a respective delivered volume measurement relative to the reference volume measurement; and
the electronics module calculates the first rate of change of the output levels based upon the current output level, a previous output level, a current delivered volume measurement corresponding to the current output level, and a previous delivered volume measurement corresponding to the previous output level.
14. The device of claim 13 , wherein:
the electronics module calculates the second rate of change based upon the current output level, an intervening output level that is determined after determining the previous output level, the current delivered volume measurement, and an intervening delivered volume measurement corresponding to the intervening output level.
15. The device of claim 11 , wherein the first threshold value is greater than the second threshold value.
16. The device of claim 11 , wherein the electronics module initiates corrective action for the fluid infusion device when an occlusion is detected.
17. The device of claim 11 , wherein the fluid is insulin.
18. The device of claim 11 , wherein each of the output levels represents a measure of actuation force imparted to the force sensor during the fluid delivery action.
19. A device for delivering fluid to a user, the device comprising:
a housing;
a reservoir cavity within the housing to accommodate a fluid reservoir;
a drive motor assembly in the housing to regulate delivery of fluid by actuating a piston of the fluid reservoir;
a force sensor associated with the drive motor assembly to generate output levels in response to force imparted thereto and each of the output levels represents a measure of actuation force imparted to the force sensor during the fluid delivery action; and
an electronics module coupled to the force sensor to process the output levels to detect occlusions in a fluid path of the device for a fluid delivery action by:
indicating an occlusion when a first rate of change of the output levels is greater than or equal to a first threshold value, the first rate of change based upon a first measurement window; and
indicating an occlusion when both: (a) a second rate of change of the output levels is greater than or equal to a second threshold value, the second rate of change based upon a second measurement window; and (b) a current output level is greater than or equal to a threshold output level,
wherein the first measurement window and the second measurement window represent a volume of fluid dispensed from the fluid reservoir relative to a reference volume measurement and the first threshold value is greater than the second threshold value.
20. The device of claim 19 , wherein:
the electronics module determines, for each of a plurality of measurement points during the fluid delivery action, a respective output level, along with a respective delivered volume measurement relative to the reference volume measurement;
the electronics module calculates the first rate of change of the output levels based upon the current output level, a previous output level, a current delivered volume measurement corresponding to the current output level, and a previous delivered volume measurement corresponding to the previous output level; and
the electronics module calculates the second rate of change based upon the current output level, an intervening output level that is determined after determining the previous output level, the current delivered volume measurement, and an intervening delivered volume measurement corresponding to the intervening output level.