Canister Fluid Level Sensor Shielding for NPWT

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Solution Overview

Problem

Existing negative pressure wound therapy devices lack accurate and reliable methods for detecting when a canister is full, leading to potential interruptions and inefficiencies in treatment due to false alarms or delayed replacements.

Innovation Solution

A negative pressure wound therapy device equipped with a fluid level sensor comprising arms extending into the canister housing, which completes an electrical circuit when fluid contacts both arms, and an electronic circuitry to indicate the canister status, protected by a mechanical shield to prevent false triggers from splashes or tipping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a fluid level sensor is used to detect canister full condition, then measurement precision is improved, but reliability deteriorates due to false triggers from fluid splashes or canister tipping

Engineering Contradiction:

Improvefluid level detection accuracyVSAvoiddetection stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A non-conductive shield is introduced as an intermediary element between the fluid and the fluid level sensor. The shield prevents direct contact between splashing fluid and the sensor, blocking false electrical circuit completion while allowing the sensor to detect the true fluid level when fluid is properly present in the canister.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful effect of fluid contact with the sensor is extracted and isolated by positioning the sensor on a raised platform or structure that elevates it above the fluid level. This separation ensures that normal fluid levels cannot trigger false detections, while still allowing legitimate full-condition detection when fluid reaches the appropriate level.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If the fluid level sensor arms are positioned to detect fluid contact, then measurement precision is improved, but object-generated harmful factors increase due to false alarms from splashes

Engineering Contradiction:

Improvefluid level detection accuracyVSAvoidfalse alarms

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The non-conductive shield acts as a mediator that blocks harmful fluid splashes from reaching the sensor arms, preventing false circuit completion and false alarms while preserving the sensor's ability to accurately detect when the canister is truly full.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shield is positioned in advance to intercept and block fluid splashes before they can contact the sensor arms. This preliminary protective action prevents false alarms from occurring in the first place, rather than attempting to correct them after detection.

Inventive Principle:

Principle #9Preliminary anti-action

3Ease of operation

If the canister is made removable for replacement, then ease of operation is improved, but device complexity increases due to additional connection components

Engineering Contradiction:

Improvecanister replacement convenienceVSAvoidconnection structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The cap structure is merged with the fluid level sensor assembly, integrating the sensor mounting function into the cap that already serves as a connection interface. This combination allows the sensor to be positioned on the cap without requiring separate mounting hardware, reducing overall device complexity while maintaining removable canister functionality.

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 accurate detection of the canister's full condition, reducing interruptions and ensuring continuous therapy by minimizing false alarms and allowing for timely canister replacements.

Implementation Method 1

the fluid level sensor is configured to detect a completed electrical circuit when the fluid aspirated from the wound comes into contact with the first and second arm of the fluid level sensor

Methodology Applied

Scientific EffectElectrical conduction through fluid: Conduction (electrical)

Implementation Method 2

a negative pressure source supported by the device housing, the negative pressure source configured to provide negative pressure to a wound covered by a wound dressing

Methodology Applied

Scientific EffectNegative pressure: Pressure Gradient

Data Source

PatentUS20250205413A1Canister status determination for negative pressure wound therapy devices

Publication Date: 2025.06.26 T J SMITH & NEPHEW

AI summary

A negative pressure wound therapy device can include one or more fluid detection systems. A canister fluid level detection system can incorporate various fluid detection devices to communicate data relating to the fluid level of the canister. In some cases, a negative pressure wound therapy device can include a device housing, a negative pressure source, and a canister configured to be in fluid communication with the negative pressure source. The canister can include a canister housing configured to store fluid aspirated from a wound, a cap connected to the canister housing, and a fluid level sensor supported by the cap. The fluid level sensor can be configured to detect a completed electrical circuit when the fluid aspirated from the wound comes into contact with the sensor. An electronic circuitry can be configured to detect a state of the sensor and provide an indication of a status of the canister.