Biocompatible Wire Processing for Fatigue-Resistant Medical Leads
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Solution Overview
Problem
Conventional methods for manufacturing biocompatible wires do not adequately address the need for improved fatigue life and mechanical properties, which are crucial for medical applications such as Cardiac Rhythmic Management and neurostimulation devices.
Innovation Solution
A method involving cold working and annealing of biocompatible metallic materials, specifically using a cold work percentage of 97 to 99% with a die reduction per pass ratio of 6 to 40% and annealing in the range of 850 to 1100°C, to produce wires with smaller grain sizes and controlled dislocation and twin densities, enhancing fatigue life and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cold working methods are used to manufacture biocompatible wires, then the manufacturing process is simple, but the fatigue life and mechanical properties are insufficient
Solution Approach 1:
The manufacturing process is divided into multiple sequential stages: cold working with specific reduction ratios, intermediate annealing, and final heat treatment. Each stage is optimized independently to achieve cumulative improvements in fatigue life and mechanical properties without requiring overly complex equipment
Solution Approach 2:
Specific parameter ranges are established for each process stage: cold work percentage (97-99%), die reduction per pass (6-40%), annealing temperature (850-1100°C), and holding time (5-30 minutes). These controlled parameter changes transform the material microstructure to enhance fatigue life while maintaining manufacturing feasibility
2Reliability
If high cold work percentage (97-99%) is applied to improve grain size control, then fatigue life improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges including cold work percentage (97-99%), die reduction per pass (6-40%), and annealing temperature (850-1100°C). These controlled parameter changes achieve consistent grain refinement to 1-10 micrometers while providing manufacturing tolerance guidance
Solution Approach 2:
The process includes intermediate annealing as a feedback mechanism to relieve excessive work hardening and prevent defects during high cold working. This staged approach with controlled intermediate treatments ensures manufacturing precision is maintained throughout the high cold work process
3Strength
If annealing temperature is increased to 850-1100°C to reduce grain size, then ductility improves, but energy consumption increases
Solution Approach 1:
The patent optimizes the annealing temperature range to 850-1100°C with holding times of 5-30 minutes, achieving grain refinement and improved ductility while minimizing energy consumption through efficient temperature control and reasonable holding times
Solution Approach 2:
The manufacturing process uses periodic thermal treatment cycles including cold working followed by intermediate annealing, and final heat treatment. This periodic application of thermal energy achieves the required microstructural changes while allowing energy recovery between cycles
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 method results in wires with improved fatigue life, higher ductility, and ultimate strength, suitable for medical applications, with specific mechanical properties like yield strength and ultimate tensile strength in the range of 1300 to 2400 MPa, and uniform grain size distribution.
Implementation Method 1
cold working the workpiece into a wire
Implementation Method 2
annealing the wire. The annealing is done in a range of 850 to 1100°C
Data Source
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AI summary
The disclosure relates to a method for manufacturing a biocompatible wire, a biocompatible wire comprising a biocompatible metallic material and a medical device comprising such wire. The method for manufacturing a biocompatible wire comprises the steps of providing a workpiece of a biocompatible metallic material, cold working the workpiece into a wire, and annealing the wire, wherein a cold work percentage is 97 to 99 %, wherein the cold working is a drawing with a die reduction per pass ratio in a range of 6 to 40 %, and wherein the annealing is done in a range of 850 to 1100°C.