Insulin Pump Plunger Detection Using Motor Rotation Variability

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Solution Overview

Problem

Existing insulin pumps face challenges in accurately and efficiently delivering insulin due to variations in reservoir friction, plunger detection, and occlusion detection, which can lead to energy inefficiency, increased complexity, and higher costs, while relying on additional sensors like strain or pressure sensors compromises reliability and durability.

Innovation Solution

The method employs motor position sensors to detect the plunger and occlusion during reservoir setup and insulin delivery, using calibrated motor rotation time variations and statistical filters to compensate for friction and detect occlusions, eliminating the need for separate strain sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain sensors or pressure sensors are added to detect plunger position and occlusion, then detection accuracy improves, but device complexity and cost increase

Engineering Contradiction:

Improveplunger detection accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The motor position sensor serves multiple functions: it detects plunger position during reservoir setup, monitors motor rotation for occlusion detection during insulin delivery, and provides feedback for closed-loop control. This eliminates the need for separate strain sensors or pressure sensors, reducing device complexity while maintaining detection accuracy

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The motor's own position sensor is used to detect plunger position and occlusion conditions without requiring external sensing components. The system leverages the existing motor control infrastructure to perform detection functions that would traditionally require additional sensors

Inventive Principle:

Principle #25Self-service

2Measurement precision

If strain sensors or pressure sensors are added to detect plunger position and occlusion, then detection accuracy improves, but manufacturing cost increases

Engineering Contradiction:

Improveocclusion detection accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The motor position sensor performs multiple detection functions including plunger position detection and occlusion monitoring, eliminating the need for additional strain sensors or pressure sensors. This reduces component count and manufacturing cost while maintaining detection accuracy

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines plunger detection and occlusion detection functions into a single sensor system (the motor position sensor), reducing the total number of components needed and simplifying the manufacturing process

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If additional strain sensors or pressure sensors are used for plunger and occlusion detection, then detection reliability improves, but device durability decreases

Engineering Contradiction:

Improvedetection system reliabilityVSAvoiddevice durability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The system uses the motor's own position sensor to perform detection functions, eliminating the need for additional strain sensors or pressure sensors that would reduce device durability. This approach maintains reliability by using the existing robust motor control system

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent removes the need for fragile strain sensors and pressure sensors from the system by extracting their detection functions and implementing them through the motor position sensor and control algorithm

Inventive Principle:

Principle #2Taking out (Extraction)

4Measurement precision

If traditional sensor-based plunger detection is used, then detection accuracy improves, but energy consumption increases

Engineering Contradiction:

Improveplunger position detection accuracyVSAvoidmotor system energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The motor position sensor and control system perform plunger detection and occlusion monitoring using the motor's own operational data, eliminating the need for additional powered sensors and reducing overall energy consumption

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The motor position sensor serves multiple functions including plunger detection and occlusion monitoring, reducing the total number of active sensing components and associated energy consumption

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20260041843A1Method of sensor-less plunger detection during insulin reservoir setup

Publication Date: 2026.02.12 MEDTRONIC MINIMED INC

AI summary

A processor-implemented method includes obtaining motor rotation data associated with a motor that is configured to rotate steadily to actuate a drive system for driving a plunger of a reservoir in a fluid delivery device; for each rotation of a plurality of rotations of the motor, based on a measured rotation time of the rotation of the motor and a previous maximum rotation time of the motor, determining a current maximum rotation time of the motor and storing the current maximum rotation time in a buffer; determining a coefficient of variation of motor rotation time based on data in the buffer; determining a change of the coefficient of variation of motor rotation time with respect to a baseline coefficient of variation of motor rotation time; and determining whether the plunger is detected based on a comparison of the change and a threshold value.