Optical Flow Sensor Impulse Analysis for Infusion Pump Control

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Solution Overview

Problem

Conventional infusion pumps lack sensitivity to pressure changes, leading to inaccurate fluid flow rate measurements and potential undetected failure modes, with inefficiencies in power consumption and reliance on skilled labor, and fail to combine the benefits of gravity infusion with controlled intravenous infusion.

Innovation Solution

An in-line fluid flow sensor system that enhances sensitivity by analyzing the response to abrupt flow rate changes, providing diagnostic information on fluid viscosity and resistance, and automatically adjusts hydrostatic pressure and inline resistance to maintain target flow rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional pressure-based sensing mechanisms are used with fluid barriers, then the pump can operate indefinitely, but the system lacks sensitivity to pressure changes and cannot accurately detect actual fluid flow rates

Engineering Contradiction:

Improvecontinuous operationVSAvoidflow rate measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces conventional pressure-based mechanical sensing mechanisms with an optical sensing system. The optical sensor detects flow rate directly through light absorption or scattering properties of the fluid, eliminating the need for mechanical fluid barriers and pressure transducers. This substitution provides both continuous reliable operation and high measurement precision simultaneously.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical intermediary (light) to measure fluid flow characteristics. Instead of directly measuring pressure through mechanical contact, the system uses light interaction with the fluid to infer flow rate, providing accurate measurements without mechanical interference or pressure loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If motor-driven pumping mechanisms are used to achieve controlled flow rates, then flow precision can be improved, but power consumption increases significantly

Engineering Contradiction:

Improveflow rate control accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic pulsatile pumping action rather than continuous motor operation. The pump delivers fluid in controlled pulses, with the optical sensor measuring flow during each pulse. This periodic action maintains flow control accuracy while significantly reducing average power consumption compared to continuous motor operation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system uses the fluid's own optical properties (absorption, scattering) as the sensing mechanism. The fluid itself provides the measurement signal without requiring external power-intensive sensing systems, enabling accurate flow measurement with minimal energy input.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If gravity-based infusion systems are used, then energy efficiency is improved and operating pressures are minimized, but the systems require skilled labor and have limited flow rate ranges

Engineering Contradiction:

Improveenergy efficiencyVSAvoidautomation capability

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent implements a closed-loop feedback control system where the optical sensor continuously monitors actual flow rate and feeds this information back to the pump controller. The controller adjusts pump pulse parameters in real-time to maintain the prescribed flow rate, eliminating the need for skilled manual adjustment while maintaining energy efficiency and safe operating pressures.

Inventive Principle:

Principle #23Feedback

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 achieves continuous flow with a wide range of flow rates, high energy efficiency, accuracy, minimal operating pressures, and reduced false alarms for air-in-line issues, while being intuitive, safe, and reliable.

Implementation Method 1

the position of an object in the flow path in which the force of the fluid flow is balanced by an opposing force

Methodology Applied

Scientific EffectForce balance: Force

Implementation Method 2

examining its response to an abrupt change in flow rate. The response of the fluid flow sensor can enhance the sensitivity of the measurement, may provide diagnostic value, and can provide additional information, such as fluid viscosity

Methodology Applied

Scientific EffectViscosity measurement through flow response: Viscometer

Data Source

PatentUS8067760B2Impulse analysis for flow sensor-based fluid control system

Publication Date: 2011.11.29 FRESENIUS KABI USA LLC

AI summary

A fluid flow control system using flow rate changes to extract additional information from an in-line flow sensor. The system provides the ability to determine a position of a movable flow sensor element of a flow sensor by illuminating a photosensitive pixel array with a light source to create a first set of pixel intensity values introducing an abrupt change to the fluid driving pressure, illuminating the photosensitive pixel array with a light source to create a second set of pixel intensity values, and calculating the difference between the first and second sets of pixel intensity values as a function of pixel position.