Adhesive Hydrogel Medical Electrode for Stable Fetal Heart Rate
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Solution Overview
Problem
Conventional medical electrodes struggle to stably measure weak fetal heart rate signals due to high noise levels caused by poor contact resistance and adhesion issues, especially when the electric terminal wobbles during measurement.
Innovation Solution
A medical electrode with an adhesive hydrogel composition that has low impedance and dynamic elastic modulus, ensuring reduced contact resistance and improved conformability to the body surface, thereby minimizing noise generation and stabilizing fetal heart rate signal measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional medical electrodes are used for measuring fetal heart rate signals, then the electrode structure is simple and easy to manufacture, but the contact resistance is high and adhesion is poor, leading to high noise levels and unstable measurements
Solution Approach 1:
The patent uses a composite adhesive hydrogel material comprising a three-dimensional polymeric matrix and a plasticizer. The polymeric matrix provides structural integrity and adhesion, while the plasticizer reduces impedance and contact resistance. This composite structure resolves the contradiction by achieving both low noise (high reliability) and maintaining a practical electrode structure suitable for manufacturing.
Solution Approach 2:
The patent optimizes specific parameters of the hydrogel: impedance between 10-1000 ohms, elastic modulus between 100-10000 Pa, and plasticizer content of 10-50 wt%. By controlling these parameters, the electrode achieves low contact resistance and high adhesion for stable fetal heart rate measurement, while keeping the overall structure manageable.
2Strength
If the adhesive hydrogel has high elastic modulus for strong adhesion, then adhesion strength is improved, but conformability to the body surface decreases, causing noise and measurement instability
Solution Approach 1:
The patent carefully balances the elastic modulus parameter, setting it between 100-10000 Pa. This range ensures the hydrogel is soft enough to conform to the curved body surface (including pregnant abdomen) while maintaining sufficient adhesion strength to prevent detachment and noise during measurement.
Solution Approach 2:
The plasticizer acts as an intermediary component that modifies the mechanical properties of the polymeric matrix. It reduces the elastic modulus to improve conformability while the matrix maintains the structural framework for adhesion, thus resolving the contradiction between strength and flexibility.
3Stability of the object's composition
If the adhesive hydrogel has high impedance for structural stability, then structural integrity is maintained, but contact resistance increases, leading to noise and poor signal quality
Solution Approach 1:
The composite hydrogel structure with polymeric matrix and plasticizer creates a material that simultaneously achieves low impedance (10-1000 ohms) for good electrical contact and structural integrity. The matrix provides structural stability while the plasticizer provides electrical conductivity, resolving the contradiction between structural integrity and low contact resistance.
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 adhesive hydrogel reduces noise interference and enhances the stability of fetal heart rate signal measurements by maintaining consistent adhesion and low contact resistance, even when the terminal wobbles, allowing for accurate detection of weak fetal heart rate signals.
Implementation Method 1
the adhesive hydrogel has low impedance and dynamic elastic modulus, ensuring reduced contact resistance and improved conformability to the body surface
Implementation Method 2
adhesive hydrogel that enables reduction of generation of noises because of low contact resistance against the body surface and excellent conformability and adhesiveness to the body surface
Data Source
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AI summary
This invention provides an adhesive hydrogel that has low contact resistance against the body surface and excellent conformability and adhesiveness to the body surface, so that noise generation can be reduced. In particular, such adhesive hydrogel enables measurements of weak fetal heart rate signals. The adhesive hydrogel according to the invention comprises a polymer matrix prepared by crosslinking-copolymerization of an acrylamide derivative, which is a nonionic polymerizable monomer comprising a polymerizable carbon-carbon double bond in a molecule, and polyfunctional (meth)acrylamide, which is a crosslinkable monomer comprising 2 or more polymerizable carbon-carbon double bonds in a molecule, water, a polyvalent alcohol, and an electrolyte salt, wherein a laminate of the adhesive hydrogel with an Ag/AgCl sheet exhibits the impedance of 1 Ω to 100 Ω at the frequency of 0.1 Hz measured in accordance with the method of ANSI/AAMI EC12:2000, and the dynamic elastic modulus G' at the frequency of 1 Hz measured at 25°C and dispersed frequencies is 1.0×103Pa to 1.0×104Pa.