Open-Cell Polyurethane Foam for Negative Pressure Wound Therapy
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Solution Overview
Problem
Conventional negative pressure wound therapy devices face issues with foam particle buildup in wounds, adhesion of foam to the wound, and tissue trauma during dressing changes, which can delay healing and irritate the wound.
Innovation Solution
A wound dressing comprising an open-cell polyurethane foam with specific tensile strength and air permeability, obtained by reacting polyisocyanate, polyester polyol, blowing agent, and catalyst, and stored in bovine serum to reduce foam particle entry and improve atraumatic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional open-cell polymer foam is used as wound dressing, then the foam can be compressed to accommodate negative pressure, but foam particles enter the wound and cause irritation and delayed healing
Solution Approach 1:
The patent uses open-cell polyurethane foam with controlled porosity to maintain compressibility while preventing particle detachment. The specific foam structure allows exudate drainage through pores while the cell walls remain intact under negative pressure, preventing particle entry into the wound.
Solution Approach 2:
The patent specifies precise parameter ranges for the polyurethane foam including tensile strength (10-100 kPa), compression modulus (0.1-10 kPa), and air permeability (100-10000 L/m²/sec). These parameter optimizations ensure the foam maintains structural integrity during compression while allowing adequate drainage.
2Volume of moving object
If foam is compressed under negative pressure, then the foam adapts to the wound space, but passages for wound exudate removal become constricted
Solution Approach 1:
The open-cell structure with controlled porosity allows the foam to be compressed while maintaining open passages for exudate flow. The interconnected pores remain patent even under compression, ensuring drainage pathways are not blocked.
Solution Approach 2:
The air permeability parameter (100-10000 L/m²/sec) is optimized to ensure adequate breathability and exudate passage even when the foam is compressed under negative pressure, balancing compression adaptability with drainage efficiency.
3Strength
If foam adheres to the wound, then the foam provides secure contact, but tissue grows into the foam causing trauma during dressing removal
Solution Approach 1:
The tensile strength parameter (10-100 kPa) is carefully controlled to provide sufficient adhesion for secure contact while preventing excessive strength that would cause tissue entanglement and trauma during dressing removal.
4Object-affected harmful factors
If additional wound contact layers are introduced to prevent adhesion, then tissue trauma is reduced, but passage of wound exudate is reduced
Solution Approach 1:
The open-cell polyurethane foam itself serves as the wound contact layer with optimized porosity and permeability, eliminating the need for additional barrier layers that would block exudate drainage while still providing appropriate adhesion characteristics.
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 solution significantly reduces undesirable foam particles in the wound, enhances drainage, and improves patient compliance by allowing gentle therapy without additional wound contact layers, leading to faster healing and reduced inflammatory activity.
Implementation Method 1
the polyurethane foam is selected in such a way that after three days of storage in bovine serum it has an advantageous tensile strength
Data Source
AI summary
A device for negative pressure wound therapy having a cover material for air-tight sealing of the wound space connected to a negative pressure source; and a wound dressing having an open-cell polyurethane foam. The open-cell polyurethane foam has special properties, in particular a tensile strength after three days of storage in bovine serum, measured in accordance with DIN 53571, between 80 kPa and 300 kPa. The open-cell polyurethane foam may be used as a wound dressing in negative pressure wound therapy.