Negative Pressure Wound Therapy Control to Prevent Actuator Stalling

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Solution Overview

Problem

Existing negative pressure wound therapy systems face challenges in efficiently adjusting therapy prescriptions to accommodate individual patient healing processes, requiring time-consuming and repetitive clinician adjustments.

Innovation Solution

A negative pressure wound therapy device with a controller that dynamically adjusts the operation of the negative pressure source based on pressure differences, employing PI or pulsed control to maintain desired pressure levels and prevent motor stalling, thereby optimizing therapy delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a negative pressure source with actuator is used to maintain desired negative pressure at the wound site, then the therapy effectiveness is improved, but the actuator may stall when the pressure difference falls below a threshold, causing treatment interruption

Engineering Contradiction:
Improvecontinuous therapy deliveryVSAvoidactuator stalling
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The controller continuously monitors the pressure difference between the desired negative pressure setpoint and the actual pressure at the wound site. When the pressure difference falls below a predetermined threshold indicating potential actuator stalling, the controller automatically transitions from continuous mode to pulsed mode, applying negative pressure in intermittent cycles to prevent stalling while maintaining therapeutic effectiveness.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the operation mode of the actuator based on real-time pressure conditions. The controller switches between continuous operation (when pressure difference is sufficient) and pulsed operation (when pressure difference is low), optimizing actuator performance and preventing stalling throughout the therapy process.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If manual adjustments to therapy prescriptions are made by clinicians, then individual patient healing needs can be addressed, but the process is time-consuming and requires frequent clinician intervention

Engineering Contradiction:
Improvecustomized therapy for individual patientsVSAvoidtime for clinician adjustments
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system automatically monitors wound pressure and dynamically adjusts actuator operation based on real-time pressure differences and predefined control parameters. This self-adjusting capability allows the therapy to adapt to individual patient healing processes without requiring frequent manual intervention from clinicians, reducing time loss while maintaining personalized treatment effectiveness.

Inventive Principle:
Principle #25Self-service

3Reliability

If the actuator operates continuously to maintain negative pressure, then optimal therapy is provided, but energy consumption increases and motor stalling risk increases

Engineering Contradiction:
Improvepressure maintenanceVSAvoidactuator energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The controller implements pulsed operation mode where the actuator applies negative pressure in periodic cycles rather than continuously. When the pressure difference indicates low flow conditions, the actuator operates intermittently with on-periods and off-periods, maintaining therapeutic pressure while significantly reducing energy consumption and eliminating the risk of motor stalling.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP4138944B1Dual mode negative pressure source operation for provision of negative pressure wound therapy
Publication Date: 2025.11.26 T J SMITH & NEPHEW
  • EP4138944B1 patent drawingFigure 1A~1B
  • EP4138944B1 patent drawingFigure 2A~2B
  • EP4138944B1 patent drawingFigure 2C

AI summary

A negative pressure source can be fluidically connected to the wound dressing, the wound dressing can be positioned to cover at least a portion of the wound, and the negative pressure source can be controlled to supply negative pressure to the wound via the fluid flow path. An actuator of the negative pressure source can be controlled to operate in a dual mode by transitioning between a proportional-integral (PI) control or proportional-integral-derivative (PID) control and a pulsed control. Stalling of the actuator can be prevented, and therapy can be provided without interruptions.