Porous Polymer Epidermal Electronics for Skin Irritation
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Solution Overview
Problem
Current epidermal electronics built on solid polymeric substrates lack efficient gas permeability, leading to skin irritation and discomfort due to sweat accumulation, and existing methods for creating gas-permeable and ultrathin materials are complex and not scalable.
Innovation Solution
A thin film epidermal electronic device with a polymer film containing conductive nanomaterials, such as silver nanowires, embedded just below the surface, forming a network that allows for gas permeability and conformal contact with the skin, fabricated using a breath figure method that involves a simple and scalable process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid polymeric substrates are used for epidermal electronics, then mechanical strength and structural stability are improved, but gas permeability deteriorates leading to skin irritation
Solution Approach 1:
The patent employs porous polymer substrates with controlled pore sizes and distributions that allow gas permeability while maintaining mechanical integrity. The porous structure enables sweat vapor transmission to prevent skin irritation, while the polymer matrix provides sufficient mechanical strength for wearable applications.
Solution Approach 2:
The patent uses composite material systems combining polymer matrices with conductive nanomaterials (such as silver nanowires, carbon nanotubes, or graphene) to achieve simultaneous mechanical strength, electrical conductivity, and gas permeability. The composite structure allows each component to contribute its optimal properties without compromising the others.
2Object-affected harmful factors
If ultrathin films are fabricated to improve gas permeability and conformal contact, then gas permeability and comfort are improved, but manufacturing complexity increases
Solution Approach 1:
The patent controls film thickness, pore size, and porosity parameters within specific ranges to achieve optimal balance between gas permeability and mechanical properties. By precisely controlling these parameters during fabrication, the patent creates ultrathin films that are both breathable and structurally sound without requiring complex multi-step processes.
Solution Approach 2:
The patent employs solution-based fabrication methods and self-assembly processes to create porous ultrathin films, replacing complex mechanical fabrication techniques. The use of dip-coating, spin-coating, or vapor deposition with controlled solvent evaporation allows simple formation of porous structures at the molecular level.
3Reliability
If conductive nanomaterials are embedded at or just below the surface, then electrical conductivity is improved while gas permeability is maintained, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses the polymer matrix as an intermediary medium to embed conductive nanomaterials at controlled depths. The polymer serves as both the structural substrate and the embedding medium, allowing nanomaterials to be positioned at or just below the surface through simple mixing or dip-coating processes, eliminating the need for precise positioning equipment.
Solution Approach 2:
The patent creates local variations in nanomaterial concentration and depth within the polymer matrix, with higher concentrations at or near the surface where conductivity is most needed for skin contact, while maintaining gas permeability in the bulk material. This local optimization achieves high conductivity without requiring uniform precision throughout the entire film.
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 provides enhanced gas permeability for sweat evaporation, improved comfort, and long-term wearability while maintaining electrical conductivity and stability, enabling effective electrophysiological sensing and human-machine interfaces.
Implementation Method 1
The conductive nanomaterials are connected to form a network of nanomaterials, thereby causing at least a part of the polymer film to act as an electrode
Implementation Method 2
one or more water droplets are formed in the polymer layer... forming one or more holes in the polymer layer by evaporating the water droplets
Data Source
AI summary
Presented herein are gas permeable, ultrathin, stretchable epidermal electronic devices and related methods enabled by self-assembled porous substrates and conductive nanostructures. Efficient and scalable breath figure method is employed to introduce the porous skeleton and then silver nanowires (AgNWs) are dip-coated and heat-pressed to offer electric conductivity. The resulting film has a transmittance of 61%, sheet resistance of 7.3 Ω/sq, and water vapor permeability of 23 mg cm−2 h−1. With AgNWs embedded below the surface of the polymer, the electrode exhibits excellent stability with the presence of sweat and after long-term wear. The present subject matter demonstrates the potential of the electrode for wearable applications—skin-mountable biopotential sensing for healthcare and textile-integrated touch sensing for human-machine interfaces. The electrode can form conformal contact with human skin, leading to low skin-electrode impedance and high-quality biopotential signals. In addition, the textile electrode can be used in a self-capacitance wireless touch sensing system.