Infusion Pump Pushrod Monitoring With Dual Encoder Verification

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Solution Overview

Problem

Existing ambulatory infusion pumps face challenges in accurately monitoring pressure conditions and encoder performance without additional sensors, which can increase complexity and failure points, and require power-efficient solutions to prevent delivery errors.

Innovation Solution

Implementing an optical encoder to monitor the linear position of a pushrod and a secondary magnetic encoder to verify the primary encoder's accuracy, eliminating the need for separate force sensors and ensuring precise medicament delivery by detecting pressure conditions and encoder errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If electrical leads and connectors are used to communicate pump operation status and alarm conditions, then information can be transmitted, but the complexity of the system increases and potential points of failure are introduced

Engineering Contradiction:
Improveinformation transmissionVSAvoidsystem complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent replaces electrical communication systems (leads and connectors) with optical communication (light transmission through the fluid path). The pump housing and fluid pathway act as an optical waveguide, transmitting alarm information as light signals without requiring additional electrical components. This substitution eliminates connectors and reduces system complexity while maintaining information transmission capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Loss of information

If electrical leads and connectors are used for communication, then data can be transmitted, but reliability decreases due to additional points of failure

Engineering Contradiction:
Improvealarm condition transmissionVSAvoidsystem reliability
Core Design Contradiction:
Loss of informationVSReliability

Solution Approach 1:

The patent eliminates electrical leads and connectors by using optical transmission through the fluid pathway. The pump housing itself serves as an optical waveguide, removing multiple potential failure points (connector contacts, wiring issues) while reliably transmitting alarm conditions through light absorption changes in the fluid.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The pump housing serves dual functions: it contains the fluid pathway for infusion and simultaneously acts as an optical waveguide for communication. This multi-functionality eliminates the need for separate communication conduits, reducing component count and improving reliability by using existing structural elements for multiple purposes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Loss of information

If complex communication systems are implemented, then comprehensive monitoring is achieved, but the device becomes more difficult to manufacture

Engineering Contradiction:
Improvepump operation status monitoringVSAvoidmanufacturing simplicity
Core Design Contradiction:
Loss of informationVSEase of manufacture

Solution Approach 1:

The pump housing is designed to serve both as a mechanical containment structure for the infusion fluid and as an optical waveguide for transmitting alarm information. This multi-functionality eliminates the need for separate communication hardware, simplifying manufacturing by using a single component for dual purposes rather than requiring assembly of multiple specialized parts.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the structural function of the pump housing with the communication function by designing it to act as an optical waveguide. The fluid pathway and housing structure are integrated to transmit light signals, combining what would traditionally be separate systems into a unified design that is simpler to manufacture.

Inventive Principle:
Principle #5Merging (Combining)

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

The system provides reliable, low-power monitoring of infusion pump performance, detecting occlusions and other conditions, reducing the risk of delivery errors, and ensuring accurate medicament administration.

Implementation Method 1

the fluid pathway and pump housing act as an optical waveguide to transmit alarm information

Methodology Applied
Scientific EffectOptical absorption: Absorption (EM radiation)

Data Source

PatentEP3749390B1Methods and systems for detecting infusion pump conditions
Publication Date: 2026.05.06 TANDEM DIABETES CARE INC
  • EP3749390B1 patent drawingFigure 1A~1C
  • EP3749390B1 patent drawingFigure 2A
  • EP3749390B1 patent drawingFigure 2B

AI summary

Disclosed herein are systems and methods for monitoring performance of an ambulatory infusion pump. An ambulatory infusion pump can include a reservoir configured to contain a medicament including a plunger at a proximal end of the reservoir and an outlet port at a distal end of the reservoir. A motor can be configured to cause linear motion of a pushrod to contact and move the plunger to cause medicament to flow from the reservoir out of the outlet port to a patient. An optical encoder can be employed to monitor a linear position of the pushrod. In addition, the optical encoder can be employed to monitor additional system conditions and/or a secondary encoder can be employed to monitor the performance of the optical encoder.