Porous Substrate Biosensor Adhesion Stability
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Solution Overview
Problem
Biological sensors with biocompatible polymer substrates tend to peel off from the skin due to movement or perspiration, leading to unstable measurement of biological information.
Innovation Solution
A biological sensor design featuring a cover member, a porous substrate with a specific shear stress and moisture permeability range, and multiple adhesive layers to ensure stable adhesion and flexibility, reducing peeling and enhancing moisture discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biocompatible polymer substrate is used for the biological sensor, then the sensor can be affixed to the living body, but the polymer layer tends to peel off from the skin due to skin movement and perspiration
Solution Approach 1:
The patent employs a composite structure consisting of a polymer layer combined with a specific adhesive layer formulation. The adhesive layer contains a polymer and an oligomer in controlled proportions, creating a composite material system that integrates the biocompatibility of the polymer with the enhanced adhesion properties of the oligomer, thereby preventing peeling while maintaining skin contact stability
Solution Approach 2:
The patent optimizes the molecular weight ratio between polymer and oligomer, controlling the number-average molecular weight of the polymer to be 10 to 100 times that of the oligomer. This parameter control ensures the adhesive layer has sufficient flexibility to accommodate skin movement while maintaining strong bonding force, resolving the contradiction between adhesion stability and peeling resistance
2Duration of action of stationary object
If the biological sensor is affixed for a long period of time, then continuous biological information measurement is achieved, but the sensor peels away from the skin during use
Solution Approach 1:
The patent controls the molecular weight parameters of the adhesive components, specifically setting the number-average molecular weight of the polymer at 10 to 100 times that of the oligomer. This parameter optimization provides balanced adhesive properties that maintain strong bonding over extended periods while accommodating physiological movements, enabling long-term stable measurement
Solution Approach 2:
The patent introduces a porous layer between the polymer layer and the skin contact surface. This porous structure allows perspiration to pass through, preventing moisture accumulation that would otherwise weaken adhesion over time. The porous material thus extends the effective measurement duration by maintaining reliable affixation despite prolonged wear
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 sensor remains stably affixed to the skin, maintaining measurement accuracy even with skin movement, and effectively managing moisture to prevent peeling.
Implementation Method 1
a porous substrate having a porous structure, the porous substrate being disposed on the cover member on a side of the living body
Data Source
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AI summary
A biological sensor that is to be affixed to a living body and is for acquiring a biological signal includes a cover member; and a porous substrate having a porous structure, the porous substrate being disposed on the cover member on a side of the living body. A sticking layer, including the porous substrate and a first adhesive layer that is disposed on the porous substrate on a side of the living body, exhibits a shear stress of from 5×104 N/m2 to 65×104 N/m2 when the sticking layer is deformed in a direction perpendicular to a thickness direction of the sticking layer by 5% to 15% of a length of the sticking layer. A moisture permeability of the sticking layer is within a range from 65 g/m2·day to 4000 g/m2·day.