Flexible Electromagnetic Sensor With Powdered Magnetic Core
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Solution Overview
Problem
The rigidity of electromagnetic sensors in minimally invasive medical instruments limits their flexibility due to the length and stiffness of coils, which are necessary for precise positioning and orientation during procedures like lung biopsies, as they often break when bent.
Innovation Solution
The development of flexible electromagnetic sensors with coils made from high magnetic permeability materials in a particulate or powdered form, compounded with flexible binders or layered as strips, allowing the coils to bend while maintaining measurement accuracy through shape sensors and correction factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coils are made long with many windings and high magnetic permeability core to improve signal strength, then measurement precision is improved, but device flexibility deteriorates and reliability worsens due to rigidity and breakage when bent
Solution Approach 1:
The patent changes the physical state of the core material from solid block to particulate/powdered form, and modifies the winding structure from tight to loose. These parameter changes allow the coil to bend without breaking while maintaining sufficient magnetic permeability for accurate measurements
Solution Approach 2:
The patent uses composite materials including magnetic particles dispersed in a flexible polymer matrix for the core, combining the magnetic properties needed for sensing with the flexibility required for minimally invasive procedures. This composite structure resolves the contradiction between measurement precision and reliability
2Adaptability or versatility
If coil diameter is reduced to fit smaller instruments, then adaptability improves for minimally invasive procedures, but signal strength deteriorates due to fewer windings and smaller area
Solution Approach 1:
The patent increases the magnetic permeability parameter of the core material to compensate for the reduced coil area. By using high-permeability magnetic particles in the flexible core, the coil maintains signal strength despite smaller diameter requirements for navigating narrow airways
Solution Approach 2:
The patent concentrates magnetic properties locally within the flexible core structure, using magnetic particles distributed throughout the polymer matrix to maximize magnetic flux density in the limited space available in small-diameter coils
3Ease of operation
If tight winding is used to reduce coil length, then device flexibility improves, but manufacturing precision deteriorates and signal strength is reduced
Solution Approach 1:
The patent segments the winding structure into loose, discrete turns rather than tight continuous winding. This segmentation allows each turn to move independently during bending while maintaining overall coil integrity and consistent magnetic properties
Solution Approach 2:
The patent changes the winding density parameter from tight to loose, and compensates by increasing core magnetic permeability. This parameter change maintains signal strength while improving flexibility and ease of manufacture
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
Enables flexible medical instruments to navigate complex anatomical paths without breaking, providing accurate position and orientation measurements by accounting for coil bending, thus enhancing the flexibility and reliability of minimally invasive procedures.
Implementation Method 1
each electromagnetic sensor includes one or more sensing coils that act as antennas and generate induced electrical signals when subjected to a magnetic field that varies with time
Implementation Method 2
the coils in electromagnetic sensors are generally long to allow many windings and generally employ a core made of a material with a high magnetic permeability
Data Source
AI summary
A medical instrument may comprise a flexible shaft and a sensing coil extending within the flexible shaft. The sensing coil may include an electrical conductor wound around a flexible core. The flexible core may comprise adjacent flexible pieces of magnetically permeable material that are configured to slide relative to each other in response to a bending of the flexible core.