Occlusion detection techniques for a fluid infusion device having a rotary pump mechanism and an optical sensor

• US 9,879,668 B2
• Filed: 06/22/2015
• Issued: 01/30/2018
• Est. Priority Date: 06/22/2015
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Yavorsky, Matthew William, Vazquez, Pablo, Ng, Anthony C.
• Primary Examiner(s): Farrar, Lauren P
• Application Number:
  US14/746,641
• Publication Number:
  US 20160369790A1
• Time in Patent Office: 953 Days
• CPC Class Codes: A61M 2005/16868 Downstream occlusion sensors
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• 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: F04B 19/025 cylinders rotating around their own axis
• CPC Class Codes: F04B 19/22 of reciprocating-piston type
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations
• CPC Class Codes: F04B 53/10 Valves; Arrangement of valves
• CPC Class Codes: F04B 53/14 Pistons, piston-rods or piston-rod connections
• CPC Class Codes: F04B 53/16 Casings; Cylinders; Cylinder liners or heads; Fluid connections
• CPC Class Codes: F04B 7/04 in which the valving is performed by pistons and cylinders coacting to open and close intake or outlet ports

Abstract

A fluid infusion device includes a fluid pump mechanism having a rotor and a stator. The rotor includes an optically detectable feature, a reference surface, and a cam element rising from the reference surface. The stator includes a cam element having a stator cam surface. The cam elements cooperate to axially displace the rotor as a function of angular position of the rotor, wherein the detectable feature rotates and axially translates as a function of angular position of the rotor. A biasing element provides force to urge the rotor cam element toward the stator cam element and toward the reference surface. A drive motor actuates the rotor to pump medication fluid from a fluid cartridge module to a body, via a subcutaneous conduit. An optical detection circuit interrogates the detectable feature during operation of the fluid pump mechanism to determine an operating condition of the fluid pump mechanism.

Claims

1. A fluid pump mechanism comprising:

a stator comprising a rotor chamber and a stator cam element having a stator cam surface; and

a rotor comprising an endcap and an axial extension section protruding from the endcap, the axial extension section shaped and sized for insertion into the rotor chamber of the stator, and the rotor further comprising an optically detectable tab located around an outer exposed surface of the endcap, a reference surface, and a rotor cam element having a variable height rising from the reference surface, the rotor cam element cooperating with the stator cam element to axially displace the rotor, relative to the stator, as a function of angular position of the rotor;

the rotor further comprising a conical tapered section having an asymmetrical profile, the conical tapered section located between the endcap and the axial extension section to remain exposed during operation of the fluid pump mechanism;

wherein the optically detectable tab rotates and axially translates as a function of angular position of the rotor; and

wherein an optical detection circuit interrogates the outer exposed surface of the endcap to detect the optically detectable tab once per revolution of the rotor, and interrogates the conical tapered section during operation of the fluid pump mechanism to determine an operating condition of the fluid pump mechanism based on a detected width of an interrogated location of the conical tapered section.

2. The fluid pump mechanism of claim 1, wherein, under normal operating conditions:

a complete rotation of the rotor corresponds to one pumping cycle comprising a fluid intake period and a fluid expulsion period;

during each pumping cycle, the optically detectable feature axially translates in accordance with a first characteristic movement; and

the optical detection circuit observes the first characteristic movement to determine that the operating condition of the fluid pump mechanism is normal.

3. The fluid pump mechanism of claim 2, wherein, under downstream occlusion conditions:

a complete rotation of the rotor corresponds to one occluded pumping cycle;

during each occluded pumping cycle, the optically detectable feature axially translates in accordance with a second characteristic movement that is optically distinguishable from the first characteristic movement; and

the optical detection circuit observes the second characteristic movement to determine that the operating condition of the fluid pump mechanism corresponds to a downstream occlusion.

4. The fluid pump mechanism of claim 3, wherein, under normal operating conditions:

one pumping cycle comprises a fluid intake period and a fluid expulsion period;

during the fluid intake period, the stator cam element is in contact with the rotor cam element;

during the fluid expulsion period, the rotor cam element disengages the stator cam element, and a biasing element axially displaces the rotor such that the rotor cam element moves toward the reference surface; and

after the fluid expulsion period and before a next fluid intake period, the rotor cam element is in contact with the reference surface.

5. The fluid pump mechanism of claim 4, wherein, under downstream occlusion conditions, fluid pressure caused by an occlusion downstream of the fluid pump mechanism prevents the rotor cam element from contacting the reference surface after the fluid expulsion period.

6. A fluid infusion device for delivering a medication fluid to a body, the fluid infusion device comprising:

a fluid pump mechanism that cooperates with a fluid cartridge module, the fluid pump mechanism comprising;

a rotor and a stator, the stator comprising a rotor chamber and a stator cam element having a stator cam surface, the rotor comprising an endcap and an axial extension section protruding from the endcap, the axial extension section shaped and sized for insertion into the rotor chamber of the stator;

the rotor further comprising an optically detectable tab located around an outer exposed surface of the endcap, a reference surface, and a rotor cam element having a variable height rising from the reference surface, wherein the optically detectable tab rotates and axially translates as a function of angular position of the rotor;

the rotor cam element cooperating with the stator cam element to axially displace the rotor, relative to the stator, as a function of angular position of the rotor;

wherein the rotor further comprises a conical tapered section having an asymmetrical profile, the conical tapered section located between the endcap and the axial extension section to remain exposed during operation of the fluid pump mechanism;

a biasing element that provides a biasing force to urge the rotor cam element toward the stator cam element and toward the reference surface;

a subcutaneous conduit in fluid communication with an outlet valve of the fluid pump mechanism;

a drive motor coupled to actuate the rotor of the fluid pump mechanism to pump medication fluid from the fluid cartridge module to the body, via the subcutaneous conduit; and

an optical detection circuit to interrogate the outer exposed surface of the endcap to detect the optically detectable tab once per revolution of the rotor, and to interrogate the conical tapered section during operation of the fluid pump mechanism to determine an operating condition of the fluid pump mechanism based on a detected width of an interrogated location of the conical tapered section.

7. The fluid infusion device of claim 6, wherein:

the fluid infusion device is a disposable insulin pump device; and

the medication fluid comprises insulin.

8. The fluid infusion device of claim 6, wherein, under normal operating conditions:

a complete rotation of the rotor corresponds to one pumping cycle comprising a fluid intake period and a fluid expulsion period;

during each pumping cycle, the optically detectable feature axially translates in accordance with a first characteristic movement; and

the optical detection circuit observes the first characteristic movement to determine that the operating condition of the fluid pump mechanism is normal.

9. The fluid infusion device of claim 8, wherein, under downstream occlusion conditions:

a complete rotation of the rotor corresponds to one occluded pumping cycle;

during each occluded pumping cycle, the optically detectable feature axially translates in accordance with a second characteristic movement that is optically distinguishable from the first characteristic movement; and

the optical detection circuit observes the second characteristic movement to determine that the operating condition of the fluid pump mechanism corresponds to a downstream occlusion.