Closed-Loop Insulin Infusion Using State Variable Feedback

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Solution Overview

Problem

Current insulin infusion systems are limited by the speed of insulin delivery and suffer from complications such as inefficiency and poor control of blood glucose levels, particularly in diabetic patients, as they do not mimic the natural insulin secretion pattern of a healthy pancreas.

Innovation Solution

A closed-loop infusion system using a proportional plus integral plus derivative (PID) controller that monitors blood glucose levels and adjusts insulin delivery to mimic the natural insulin secretion profile of a healthy pancreas, incorporating a sensor system to measure glucose concentration and a delivery system to infuse insulin based on real-time feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If traditional external infusion pumps are used to deliver insulin, then insulin can be provided to the body, but the system is limited by the speed of insulin delivery and cannot mimic natural insulin secretion patterns

Engineering Contradiction:
Improveinsulin delivery speedVSAvoidglucose control accuracy
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent implements a closed-loop control system that continuously monitors blood glucose levels and adjusts insulin delivery rates in real-time based on feedback from glucose sensors. This feedback mechanism enables the system to respond dynamically to changing glucose levels, overcoming the limitation of fixed-speed infusion pumps and achieving both rapid response capability and accurate glucose control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system transitions from static, fixed-rate insulin delivery to dynamic, adaptive infusion rates that continuously adjust based on real-time glucose measurements. The controller modifies infusion parameters dynamically to match natural insulin secretion patterns, allowing the system to achieve both speed and accuracy in glucose control.

Inventive Principle:
Principle #15Dynamics

2Reliability

If fast acting insulin is used to improve glucose control, then insulin profiles can be changed, but the limitation due to the speed of insulin used remains

Engineering Contradiction:
Improveglucose control accuracyVSAvoidinsulin delivery efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The closed-loop feedback system continuously monitors glucose levels and adjusts insulin delivery rates to optimize both the speed and efficiency of insulin action. By matching natural insulin secretion patterns through feedback control, the system achieves effective glucose control without being limited by the pharmacokinetic properties of the insulin formulation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes infusion parameters including rate, timing, and duration of insulin delivery to optimize both speed and efficiency. The controller adjusts these parameters in real-time based on glucose levels, allowing the system to overcome limitations of specific insulin formulations by adapting delivery characteristics rather than being constrained by them.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of stationary object

If traditional infusion pump therapy is used, then insulin can be delivered continuously, but complications arise including inefficiency and poor control of blood glucose levels

Engineering Contradiction:
Improvecontinuous insulin deliveryVSAvoidglucose control accuracy
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent implements continuous feedback control where glucose sensors continuously monitor blood glucose levels and the controller adjusts insulin delivery in real-time based on this feedback. This closed-loop system maintains accurate glucose control throughout the continuous delivery period, eliminating the inefficiency and poor control associated with traditional open-loop infusion pumps.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-regulation by automatically adjusting its own insulin delivery rates based on real-time glucose measurements without requiring manual intervention. This self-service capability enables continuous delivery while maintaining accurate glucose control, as the system adapts to changing physiological conditions autonomously.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2114491B1Apparatus for controlling insulin infusion with state variable feedback
Publication Date: 2016.03.09 MEDTRONIC MINIMED INC
  • EP2114491B1 patent drawingFigure 1
  • EP2114491B1 patent drawingFigure 2
  • EP2114491B1 patent drawingFigure 3A~3B

AI summary

An infusion system, which may be a closed loop infusion system or "semi-closed-loop" system', uses state variable feedback to control the rate that fluid is infused into the body' of a user. The closed loop infusion system includes a sensor system, a controller, and a delivery system. The "semi-closed-loop" system further includes prompts that are displayed or sounded or otherwise provide indications to the user prior to insulin delivery. The sensor system includes a sensor for monitoring a condition of the user. The sensor produces a sensor signal, which is representative of the condition of the user. The delivery system infuses a liquid into the user at a rate dictated by the commands from the controller. The system may use three state variables, subcutaneous insulin concentration, plasma insulin concentration, and insulin effect, and corresponding gains, to calculate an additional amount of liquid to be infused as a bolus and to be removed from 'the basal delivery ' rate of the liquid.