Injection Device Occlusion Detection Using Dynamic Evaluation Time

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Solution Overview

Problem

Automatically operating injection devices face challenges in accurately detecting occlusions, which can lead to increased pressure, potential damage, and inconsistent medicament delivery, as existing methods rely on force measurements that may not reliably distinguish between occlusions and normal operation.

Innovation Solution

The injection device incorporates a measurement unit to record and evaluate injection forces over adjustable time periods, using a combination of force threshold comparison, FIR filtering, and median calculation to generate occlusion alarms, thereby enhancing the accuracy and reliability of occlusion detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If force measurement is used to detect occlusion, then occlusion detection capability is provided, but false alarms occur due to inability to distinguish occlusions from normal operation

Engineering Contradiction:

Improveocclusion detection accuracyVSAvoidforce measurement reliability

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The evaluation time period is made dynamically adjustable based on the injection time period. When the injection time period changes, the evaluation time period is adapted accordingly, allowing the system to optimize its detection sensitivity and specificity for different operating conditions, thereby reducing false alarms while maintaining occlusion detection accuracy

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the evaluation parameter (evaluation time period) based on operating conditions (injection time period). By adjusting the evaluation time period to match the injection time period, the system optimizes the force measurement evaluation to distinguish between normal force variations and true occlusions, improving measurement precision

Inventive Principle:

Principle #35Parameter changes

2Productivity

If automatic injection is implemented, then productivity is improved, but pressure increase causes device damage risk

Engineering Contradiction:

Improveinjection automationVSAvoidpressure damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system continuously monitors injection force and provides feedback by comparing measured forces against threshold values over an evaluation time period. When occlusion is detected through this feedback mechanism, the system can alert the user or stop operation, preventing pressure buildup that could damage the device while maintaining automatic injection functionality

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary evaluation of force measurements over an adjustment period before making occlusion determination. This preliminary action allows the system to establish baseline force characteristics under normal operation, enabling more accurate occlusion detection and preventing false positives that could interrupt automatic injection

Inventive Principle:

Principle #10Preliminary action

3Speed

If force threshold comparison is used, then occlusion detection speed is improved, but measurement precision deteriorates

Engineering Contradiction:

Improveocclusion detection speedVSAvoidocclusion determination accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The force measurement evaluation is segmented into multiple components: individual force measurements, threshold comparisons, and aggregate evaluation over the evaluation time period. This segmentation allows the system to perform quick threshold checks while maintaining overall detection accuracy through cumulative evaluation of multiple force measurements

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs partial evaluation by comparing individual force measurements against threshold values for quick detection, while also performing excessive evaluation by accumulating and evaluating multiple force measurements over the evaluation time period. This multi-level approach balances detection speed with precision

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for quick and accurate detection of occlusions, reducing the risk of device damage and ensuring consistent medicament delivery by minimizing false alarms and improving the determination of occlusion presence.

Implementation Method 1

the measurement unit is mechanically coupled to the injection unit and measures an injection force, at the injection time period, for each of the plurality of injections

Methodology Applied

Scientific EffectForce measurement: Force

Data Source

PatentUS8618948B2Automatically operating injection device and method for determining an injection occlusion

Publication Date: 2013.12.31 ROCHE DIAGNOSTICS INTERNATIONAL AG

AI summary

An automatically operating injection device with an occlusion alarm unit and a method for determining an injection occlusion are disclosed. The method includes generating a plurality of evaluation forces based on a series of force measurements and based on an evaluation time period; determining whether an occlusion exists based on either an evaluation of the plurality of evaluation forces or whether one or more of the series of force measurements exceeds a force threshold; and providing an injection occlusion alarm if an occlusion is determined to exist.