Capacitive Sensing for Flexible Drug Reservoir Volume Detection

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Solution Overview

Problem

Conventional drug delivery systems with rigid reservoirs face inefficiencies in volume usage due to the need for a constant cross-section for plunger travel, and existing methods for detecting fill volume in flexible reservoirs often restrict fluid flow, making them less effective.

Innovation Solution

The use of capacitive sensing electrodes and pressure sensors integrated into flexible reservoirs to detect fill volume without restricting fluid flow, allowing for variable cross-sections and efficient drug delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a rigid reservoir with a plunger is used to store liquid drug, then the liquid drug can be released through plunger travel, but the reservoir requires a constant cross-section which leads to inefficiencies in volume usage

Engineering Contradiction:

Improvevolume usage efficiencyVSAvoidconstant cross-section requirement

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The patent transitions from a rigid reservoir with constant cross-section to a flexible reservoir with variable cross-section that can dynamically change shape as fluid is expelled. The flexible reservoir contracts as fluid leaves, allowing efficient volume usage without requiring a plunger mechanism, thereby resolving the contradiction between manufacturing efficiency and shape constraints.

Inventive Principle:

Principle #15Dynamics

2Productivity

If a flexible reservoir is used to improve volume usage efficiency, then variable cross-section is achieved, but existing fill volume detection methods (flow meters, orifice monitors, pressure sensors) restrict fluid flow and reduce filling and extraction efficiency

Engineering Contradiction:

Improvefilling and extraction efficiencyVSAvoidfluid flow restriction

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent replaces mechanical detection methods (flow meters, orifice monitors, pressure sensors) that physically restrict fluid flow with capacitive sensing electrodes that detect fill volume through electrical capacitance changes. This substitution eliminates fluid flow restrictions while maintaining accurate fill volume detection, thereby resolving the contradiction between productivity and quantity of substance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent detects fill volume by monitoring changes in electrical capacitance parameter rather than using mechanical flow restriction methods. The capacitive sensing electrodes measure capacitance changes that correlate with fill volume, allowing non-intrusive detection that does not impede fluid flow, thus maintaining both high productivity and full fluid flow capacity.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If conventional detection methods (flow meters, orifice monitors, pressure sensors) are used with flexible reservoirs, then fill volume can be detected, but the detection devices restrict fluid flow and reduce system efficiency

Engineering Contradiction:

Improvefill volume detection accuracyVSAvoidfluid flow restriction

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent substitutes electrical field-based capacitive sensing for mechanical detection devices. The capacitive sensing electrodes detect fill volume through changes in electrical capacitance caused by the dielectric properties of the liquid drug, eliminating the need for physical flow restriction elements and thereby maintaining both measurement precision and unrestricted fluid flow.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables accurate detection of fill volume in flexible reservoirs without impairing the flow of liquid, enhancing the efficiency and performance of drug delivery systems by decoupling fill sensing from fixed geometry, allowing for precise monitoring of liquid levels.

Implementation Method 1

The capacitive sensing component may be is operable to detect a capacitance between the pair of capacitive sensing electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The capacitive pressure sensor comprises a first electrode, a second electrode, an elastic component positioned between the first and second electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11458250B2System and techniques for drug reservoir volume detection

Publication Date: 2022.10.04 INSULET CORP

AI summary

Reservoir systems with improved wake up and fill volume detection techniques are provided. An example reservoir system may include a flexible reservoir and electrical components for detecting fill volume of the flexible reservoir without adversely affecting performance of the flexible reservoir when receiving or dispensing a liquid drug.