Non-metallic IPG Case with Optical Reflectometry for Spinal Cord Stimulation
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Solution Overview
Problem
Current spinal cord stimulation systems face challenges in maintaining optimal electrode current due to changes in spinal cord position, leading to inadequate or excessive stimulation, and suffer from issues like device erosion, biocompatibility concerns, and inefficient recharging times, with inaccuracies in lead coupling and optical signal stability.
Innovation Solution
The design incorporates a non-metallic IPG case for continuous charging, a super ellipse curve for reduced erosion, ceramic or glass casing for biocompatibility, canted coil connectors for secure lead attachment, and dual optical reflectometry channels for precise spinal cord position detection, along with a lithium-ion battery for efficient recharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional metallic IPG case is used, then structural strength is maintained, but device erosion and biocompatibility issues occur
Solution Approach 1:
The patent employs a composite construction where a metallic shell provides structural strength and hermetic sealing, while a non-metallic coating layer (such as PEEK, polyimide, or other biocompatible polymers) is applied to the outer surface to eliminate device erosion and improve biocompatibility. This composite approach allows the device to simultaneously achieve mechanical integrity and biocompatibility without sacrificing strength.
2Ease of operation
If optical fiber is loosely coupled in lead channel, then ease of assembly is improved, but optical signal stability deteriorates
Solution Approach 1:
The patent employs a curved or angled optical window at the distal end of the lead channel that directs light onto the optical fiber core. This curved geometry naturally guides and focuses the optical signal, improving coupling efficiency and signal stability without requiring complex alignment mechanisms, thus maintaining ease of assembly while enhancing reliability.
Solution Approach 2:
The patent introduces an optical coupling element or window as an intermediary between the light source and the optical fiber. This intermediary component facilitates efficient light transmission into the fiber core, ensuring stable optical coupling without requiring precise manual alignment during assembly, thereby maintaining both ease of operation and signal stability.
3Reliability
If lead is secured with anchor screw at distal end, then lead coupling stability is improved, but optical fiber alignment precision deteriorates
Solution Approach 1:
The patent divides the lead securing function into two separate components: a distal anchor screw that provides mechanical stability and fixation, and a proximal alignment feature (such as a tapered section or keyed interface) that ensures precise optical fiber alignment. This segmentation allows each component to optimize its specific function without compromising the other, maintaining both coupling stability and alignment precision.
Solution Approach 2:
The patent incorporates pre-formed alignment features (such as tapered sections, keys, or registration pins) in the lead body that automatically guide and position the optical fiber correctly during assembly, before the anchor screw is tightened. This preliminary alignment action ensures precise optical coupling is established prior to final mechanical securing, maintaining both alignment precision and coupling stability.
4Stability of the object's composition
If spinal cord position changes, then physiological movement is maintained, but stimulation accuracy deteriorates
Solution Approach 1:
The patent employs optical reflectometry that continuously monitors the distance between the electrode array and the spinal cord by analyzing reflected light intensity. This feedback mechanism detects changes in spinal cord position in real-time and automatically adjusts stimulation parameters to maintain optimal therapeutic effect, ensuring stimulation accuracy is preserved despite physiological movements of the spinal cord.
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
This configuration ensures stable and accurate spinal cord stimulation, reduces device erosion, enhances biocompatibility, and shortens recharging times by maintaining a consistent optical signal and precise lead coupling, thereby improving therapeutic efficacy and device longevity.
Implementation Method 1
The lead further comprises an optical fiber positioned within the stylet channel and configured to transmit light through the lead body
Implementation Method 2
The lead further comprises electrical conductors positioned within the lead body and configured to provide electrical connection between the electrode array and the pulse generator
Data Source
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AI summary
An implantable pulse generator is provided comprising a non-metallic shell adjacent a header. The header abuts an optical window in the shell. The header aligns a series of surgical or percutaneous leads with the optical window. The leads incorporate optical fibers, electrodes and contacts which distribute stimulation signals. Behind the optical window, a set of optical devices is provided which transmit or receive light from the fibers. Signal processors are provided to interpret the signals from the optical fibers, and to mitigate a continuous inductive charging function.