Flexible Magnetic Wire for Simultaneous Kidney Stone Retrieval
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Solution Overview
Problem
Current methods for retrieving kidney stone fragments, such as ureteroscopy and laser lithotripsy, are inefficient and costly, with conventional wire baskets limited to capturing one fragment at a time, and magnetic tools face challenges due to size and magnetic force limitations, leading to incomplete stone removal and increased surgical time.
Innovation Solution
A flexible magnetic wire (MagWIRE) with alternating polarity magnets within a sheath is used to attract superparamagnetic nanoparticles bound to stone fragments, allowing multiple fragments to be retrieved simultaneously, enhancing flexibility and reducing the need for precise manual guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional wire baskets are used to retrieve stone fragments, then individual fragments can be captured, but multiple fragments cannot be retrieved simultaneously and surgical time increases
Solution Approach 1:
The patent replaces the mechanical wire basket system with a magnetic field-based retrieval system. Superparamagnetic nanoparticles are instilled into the urinary tract to bind to stone fragments, and a magnetic wire with alternating polarity magnets attracts these nanoparticle-coated fragments magnetically, enabling simultaneous retrieval of multiple fragments without mechanical manipulation
Solution Approach 2:
The patent introduces superparamagnetic nanoparticles as an intermediary substance that binds to stone fragments and responds to magnetic fields. These nanoparticles act as a mediator between the magnetic wire and the stone fragments, enabling magnetic attraction and simultaneous retrieval of multiple fragments throughout the urinary tract
2Force
If a single large magnet is used for magnetic retrieval, then magnetic force is concentrated, but visualization is poor and magnetic forces are insufficient
Solution Approach 1:
The patent divides a single large magnet into multiple smaller alternating polarity magnets arranged along a flexible wire. This segmentation distributes the magnetic force throughout the urinary tract while maintaining strong local magnetic fields, and the thin wire profile improves visualization compared to a single large magnet
Solution Approach 2:
The patent uses alternating polarity magnets (north-south-north-south arrangement) rather than uniform polarity magnets. This asymmetric magnetic configuration creates strong magnetic field gradients that enhance the attraction force on superparamagnetic nanoparticles while allowing the magnetic wire to be thin and flexible for better visualization
3Productivity
If multiple alternating polarity magnets are used in a flexible wire, then multiple stone fragments can be retrieved simultaneously, but device complexity increases
Solution Approach 1:
The magnetic wire serves multiple functions: it provides structural support as a flexible catheter, generates magnetic fields through alternating polarity magnets for fragment attraction, and allows navigation through the urinary tract. This multi-functionality consolidates what would otherwise require separate components into a single integrated device
Solution Approach 2:
The patent uses a flexible wire sheath to enclose the alternating polarity magnets, allowing the device to navigate the curved anatomy of the urinary tract. The flexible construction reduces complexity compared to rigid structures while maintaining magnetic functionality throughout the procedure
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 MagWIRE enables efficient retrieval of multiple stone fragments with reduced operative time and cost, improving stone-free rates and patient outcomes by capturing fragments of various sizes without causing trauma to the urinary tract.
Implementation Method 1
A flexible magnetic wire (MagWIRE) with alternating polarity magnets within a sheath is used to attract superparamagnetic nanoparticles bound to stone fragments
Implementation Method 2
attract superparamagnetic nanoparticles bound to stone fragments
Data Source
AI summary
A medical device for retrieval of kidney stone fragments from a urinary tract is provided. The medical device has a plurality of magnets arranged within a flexible sheath forming a flexible wire. The magnets are magnetically attached end-to-end and arranged with their magnetic polarities alternating in direction. The magnetization direction of each of the magnets is orthogonal to the length axis of the flexible wire. A removable inner stylet is situated within the flexible sheath allowing for modifiable flexibility of the wire. The medical device is dimensioned to be introduced into the urinary tract and standard endoscopic devices. The medical device is further dimensioned to allow for the wire with magnetically attached stone fragments to be retrieved from the urinary tract. The magnetic field along the length axis is sufficient to attract to the surface of the flexible wire superparamagnetic nanoparticles which have bound themselves to kidney stone fragments.