Flexible TTFields Electrode Assembly With Fluoropolymer-Coated Pads
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Solution Overview
Problem
Existing electrode assemblies for Tumor Treating Fields (TTFields) therapy are stiff, making them difficult to position and causing discomfort, and the use of high-dielectric polymers like Poly(VDF-TrFE-CTFE) leads to metal pad degradation during manufacturing and use.
Innovation Solution
A flexible electrode assembly using conductive pads with layers of nickel, palladium, and gold on a polyimide substrate, combined with thin layers of high-dielectric polymers such as Poly(VDF-TrFE-CTFE) to enhance capacitance, and a self-adhesive backing for skin adherence, while incorporating thermistors for temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-dielectric polymers like Poly(VDF-TrFE-CTFE) are used to enhance capacitance, then TTFields delivery effectiveness is improved, but metal pad degradation occurs during manufacturing and use
Solution Approach 1:
The patent employs a multi-layer composite structure consisting of nickel, palladium, and gold layers. The nickel layer provides mechanical strength and serves as a barrier to diffusion, the palladium layer offers corrosion resistance and intermediate bonding, and the gold layer ensures electrical conductivity and contact stability. This composite material approach allows the use of high-dielectric polymers for enhanced capacitance while protecting the metal pad structure from degradation.
Solution Approach 2:
Each layer in the metal pad structure is assigned specific functional properties tailored to its role: the nickel layer is optimized for mechanical strength and diffusion barrier properties, the palladium layer for corrosion resistance and bonding, and the gold layer for electrical conductivity. This local optimization of material properties at different interfaces enables the system to withstand the demands of high-dielectric polymer integration while maintaining overall stability.
2Reliability
If flexible polymer regions with high dielectric constant are used, then capacitance and TTFields effectiveness are enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes thin film flexible polymer regions with high dielectric constants (greater than 10 at TTFields frequencies) disposed on the conductive pads. These thin films can be deposited using standard semiconductor manufacturing techniques such as spin coating, dip coating, or vapor deposition, which maintains manufacturing simplicity while achieving the required capacitance enhancement through the high dielectric constant material properties.
3Reliability
If rigid ceramic discs are used as electrode assemblies, then electrical insulation is maintained, but positioning difficulty and user discomfort increase
Solution Approach 1:
The patent replaces rigid ceramic discs with flexible insulating substrate and flexible polymer regions that can conform to the contours of the patient's body. This flexibility enables easy positioning on curved or irregular body surfaces while maintaining electrical insulation through the inherent insulating properties of the polymer materials and the multi-layer metal pad structure.
Solution Approach 2:
The electrode assembly transitions from a static, rigid structure to a dynamic, flexible system that can adapt its shape and position to match the patient's body contours. This dynamic adaptability is achieved through the flexible insulating substrate and flexible polymer regions that can be deformed and repositioned without compromising electrical insulation or structural integrity.
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 flexible design improves positioning and comfort, maintains high capacitance for effective TTFields delivery, and prevents metal degradation, ensuring reliable and efficient treatment.
Implementation Method 1
Each of the plurality of flexible polymer regions has a dielectric constant that is greater than 10 at at least one frequency between 50 kHz and 1 MHz
Implementation Method 2
An AC voltage is applied between opposing electrode assemblies, an AC current is capacitively coupled through the electrode assemblies and into the subject's body
Implementation Method 3
The plurality of thermistors are positioned on a rear side of the flexible insulating substrate, and each of the plurality of thermistors is in thermal contact with a respective one of the plurality of conductive pads
Data Source
AI summary
Alternating electric fields (e.g., TTFields) can be applied to a subject's body using a pair of electrode assemblies, each of which includes a flexible insulating substrate and a plurality of conductive pads disposed on a front side of the flexible insulating substrate. Each of the conductive pads includes a layer of nickel, a layer of palladium disposed on a front side of the layer of nickel, and a layer of gold disposed on a front side of the layer of palladium. A plurality of flexible polymer regions made from Poly(VDF-TrFE-CtFE), Poly(VDF-TrFE-CFE), and/or Poly(VDF-TrFE-CFE-CTFE) are disposed on the front side of the conductive pads. When an AC voltage is applied between the pair of electrode assemblies, an AC current will be capacitively coupled into the subject's body, which will induce the alternating electric fields in the subject's body.