Compliant End Effector for Microwave Tissue Ablation
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Solution Overview
Problem
Conventional medical devices for thermal ablation, such as inflatable balloons, face issues with rigid lossy materials that lose stretchability and have inadequate microwave energy absorption, leading to uneven and unpredictable tissue heating due to insufficient particle density and leakage of microwave energy.
Innovation Solution
An adjustable, compliant end effector structure made from materials like rubber, foam, or gel with evenly dispersed electromagnetic energy absorbing particles, which conforms to the cavity shape and absorbs microwave energy for efficient tissue ablation, allowing for customizable shapes and reduced friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lossy materials (ferrite or graphite particles) are added to the balloon wall or coating to absorb microwave energy, then microwave energy absorption is improved, but the balloon wall becomes substantially rigid and loses stretchability
Solution Approach 1:
The patent changes the physical state of the microwave-absorbing material from solid particles embedded in a rigid matrix to a slurry or paste form that can be applied as a coating. This allows the material to maintain microwave absorption properties while conforming to the flexible balloon wall structure, resolving the contradiction between energy absorption and stretchability.
Solution Approach 2:
The patent creates a composite coating structure where microwave-absorbing particles (ferrite or graphite) are suspended in a flexible binder matrix. This composite allows the coating to simultaneously absorb microwave energy and stretch with the balloon wall, eliminating the rigidity problem while maintaining energy absorption capability.
2Adaptability or versatility
If the balloon wall is made very thin to maintain flexibility, then stretchability is improved, but it is impossible to have sufficient quantity of microwave absorbing particles to completely absorb microwave energy
Solution Approach 1:
The patent transitions from embedding particles within a thin wall structure to applying a multi-layer coating on the outer surface of the balloon. This dimensional change allows sufficient particle quantity to be achieved in the coating layer without compromising the thinness and flexibility of the balloon wall itself.
Solution Approach 2:
The patent uses a flexible balloon wall as a substrate and applies microwave-absorbing material as a separate coating layer. This allows the wall to remain thin and flexible while the coating provides sufficient microwave absorption capacity, resolving the contradiction between wall thinness and particle quantity.
3Temperature
If conventional wire resistance heater is used with liquid circulation for heating, then heating can be achieved, but heating is slow and requires complex liquid circulation system
Solution Approach 1:
The patent replaces the mechanical liquid circulation heating system with an electromagnetic heating system. Microwave energy directly heats the microwave-absorbing coating material, which then transfers heat to the tissue. This eliminates the need for liquid circulation pumps and pipes, dramatically increasing heating speed while simplifying the system.
Solution Approach 2:
The patent utilizes the dielectric heating effect where microwave energy causes molecular rotation and friction in the microwave-absorbing material, converting electromagnetic energy directly into thermal energy. This phase transition from electromagnetic to thermal energy provides rapid heating without mechanical fluid circulation.
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 compliant structure ensures even tissue heating, reduces the risk of device failure, and enhances the absorption of microwave energy per unit surface area, facilitating more effective and predictable tissue ablation.
Implementation Method 1
microwave energy will heat an adjustable structure of the electromagnetic energy absorbing material
Implementation Method 2
particles made of electromagnetic energy absorbing material... microwave energy will heat an adjustable structure
Implementation Method 3
microwave energy will heat an adjustable structure of the electromagnetic energy absorbing material, which heat energy will ablate he body cavity tissue
Data Source
AI summary
An adjustable, structure providing an ablation apparatus, having a preformed structure made from compliant material such as rubber like material, foam or gel, with particles made of electromagnetic energy absorbing material. An antenna for radiating emitted microwave energy to generate heat and thus cause cavity ablation is located inside of the conformable adjustable structure. When end effector portion is inserted into the body cavity, the compliant adjustable structure is compliant to conform to a profile of the cavity to be ablated, and microwave energy is received to heat the adjustable structure resulting in heat energy that will ablate the cavity tissue in contact with the compliant end effector. Additionally, the shape of the end-effector compliant structure can be differently formed, depending of shape of tissue cavity to be ablated.