Infusion Device Sensor Drift Detection and Correction

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Solution Overview

Problem

Infusion devices face challenges in reliably detecting occlusions in infusion lines due to inaccuracies caused by drift in force sensor measurements, which can lead to false alarms and alarm fatigue, necessitating a method to accurately monitor pressure within the infusion lines.

Innovation Solution

The infusion device incorporates a diagnosis routine performed by the processor device to detect and correct drift in sensor signals, distinguishing between zero drift and span drift, allowing for reliable force measurements and occlusion detection by comparing actual sensor signals to expected values and initiating appropriate countermeasures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If force sensor measurements are used to monitor infusion pressure, then occlusion detection capability is improved, but measurement accuracy deteriorates due to sensor drift

Engineering Contradiction:
Improveocclusion detection capabilityVSAvoidforce measurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary calibration measurements during manufacturing to establish baseline sensor characteristics. Expected sensor signals are pre-calculated and stored in memory based on these calibration data, enabling later comparison during operation to detect drift before it causes false occlusion alarms.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously compares actual sensor signals against expected sensor signals during infusion operation. When deviations indicate drift, the system can trigger alerts or adjust monitoring thresholds, creating a feedback loop that maintains reliable occlusion detection despite sensor aging or temperature variations.

Inventive Principle:
Principle #23Feedback

2Device complexity

If sensor drift is not corrected, then device complexity remains low, but false alarm rate increases causing alarm fatigue

Engineering Contradiction:
Improvesystem simplicityVSAvoidalarm accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The system performs self-diagnosis by automatically comparing its own sensor readings against pre-stored expected values. The processor device independently detects drift conditions and can trigger appropriate responses without requiring external calibration equipment or complex intervention systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system monitors changes in sensor signal parameters over time and compares them against expected ranges. When parameters deviate beyond acceptable thresholds indicating drift, the system adjusts its operation or alerts the user, maintaining reliability without requiring physical sensor replacement or recalibration during use.

Inventive Principle:
Principle #35Parameter changes

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 ensures accurate detection of occlusions and prevents false alarms by accounting for sensor drift, maintaining reliable operation and user safety by ensuring precise pressure monitoring within the infusion lines.

Implementation Method 1

a strain gauge arrangement, such as a Wheatstone bridge circuit, fixed on the sensor support. If a force is exerted on the load cell, a (bending) deformation of the sensor support will cause an electric signal within the strain gauge arrangement placed on the sensor support, such electric signal being proportional to the force exerted on the load cell

Methodology Applied
Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentEP3463511B1Infusion device and method allowing for detecting a drift in a sensor signal
Publication Date: 2022.05.25 FRESENIUS VIAL
  • EP3463511B1 patent drawingFigure 1
  • EP3463511B1 patent drawingFigure 2~4
  • EP3463511B1 patent drawing

AI summary

An infusion device (1) for administering a medical fluid to a patient (P) comprises a pumping mechanism (11) for exerting a force onto a delivery set (2, 3) for delivering a medical fluid from the delivery set towards a patient (P), a sensor device (14) for measuring the force exerted on the delivery set (2, 3) by the pumping mechanism (11), the sensor device (14) being constituted to output a sensor signal indicative of the force exerted onto the delivery set (2, 3), and a processor device (15) for controlling operation of the infusion device (1). Herein, the processor device (15) is constituted to perform a diagnosis routine during which a sensor signal of the sensor device (14) is obtained and compared to an expected sensor signal, to allow for detecting a drift in the sensor signal of the sensor device (14).