Beta Titanium Alloy Cables for Medical Leads
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Solution Overview
Problem
Medical device leads, particularly those used in implantable stimulation systems, face challenges with wire durability and resistance matching due to the limitations of traditional materials like MP35N, which become brittle and prone to failure under repeated stress and strain, leading to shorter device lifespan and increased replacement needs.
Innovation Solution
The use of biocompatible beta titanium alloys with an elastic modulus ranging from 30 GPa to 90 GPa, such as Ti-15Mo, for forming wires and cables, which are heated to a stress-relieve temperature to maintain a twisted configuration and provide improved ductility and resistance tuning, enhancing the wires' ability to withstand repeated forces and maintain signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional materials like MP35N are used for wires, then the wires can be manufactured with standard processes, but the wires become brittle and prone to failure under repeated stress and strain
Solution Approach 1:
The patent changes the material parameters by using beta titanium alloy instead of traditional MP35N, and by controlling the elastic modulus to be between 30-90 GPa. This parameter change transforms the material from brittle to ductile while maintaining reliability under repeated stress
Solution Approach 2:
The patent uses composite construction with multiple wires twisted together to form cables, where each wire is made of beta titanium alloy. This composite structure enhances overall durability and resistance to repeated stress while maintaining flexibility
2Stability of the object's composition
If wires are heated to stress-relieve temperature to maintain twisted configuration, then the wires remain twisted after force removal, but the heating process requires precise temperature control
Solution Approach 1:
The patent utilizes phase transition of beta titanium alloy at specific temperatures. By heating to stress-relieve temperature, the material undergoes phase changes that allow it to maintain the twisted configuration after cooling, while the patent specifies keeping the temperature below the alpha-beta transition temperature to avoid unwanted phase changes
Solution Approach 2:
The patent carefully controls the temperature parameter during heating, specifying that it should be below the alpha-beta transition temperature of the beta titanium alloy. This precise parameter control enables configuration retention without requiring extremely high temperatures
3Loss of energy
If cable resistance is tuned to match element resistance, then signal transmission quality improves and power losses reduce, but the resistance tuning process adds manufacturing complexity
Solution Approach 1:
The patent tunes the resistance parameter of the cable by controlling wire dimensions, material composition, and length. This parameter adjustment matches the cable resistance to the element resistance, minimizing power loss and improving signal transmission quality
4Reliability
If multiple cables are positioned within separate lumens of the lead body, then signal isolation and transmission quality improve, but the lead body structure becomes more complex
Solution Approach 1:
The patent divides the lead body into multiple separate lumens, with each lumen containing a specific cable. This segmentation provides electrical isolation between cables, improving signal transmission quality and reducing interference, while organizing the complex structure into manageable separate channels
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 beta titanium alloy wires offer superior durability, longer device lifespan, improved resistance matching, and reduced power losses, allowing for more efficient signal transmission and extended implant life by maintaining flexibility and preventing brittleness, thus addressing the limitations of traditional materials like MP35N.
Implementation Method 1
the cable may be heated to the stress-relieve temperature of the beta titanium alloy. Once so heated, the wires of the cable will remain twisted together after the cabling force is removed
Data Source
AI summary
Techniques are disclosed related to cables that may be used within a medical device. According to one example, a cable may comprise multiple wires. Each wire may be formed of a biocompatible beta titanium alloy having an elastic modulus ranging from 30 GigaPascals (GPa) to 90 GPa and comprising at least two elements selected from a group of titanium, molybdenum, niobium, tantalum, zirconium, chromium, iron and tin. The cable may be heated to a stress-relieve temperature of the beta titanium alloy to allow the cable to retain a desired configuration while remaining ductile. The cable may be included within a medical device, such as a medical electrical lead.