Implantable Pulse Generator Housing for Stable Optical Sensing
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Solution Overview
Problem
Existing implantable pulse generators (IPGs) for spinal cord stimulation face challenges such as long-term survival in the harsh in vivo environment, device erosion due to tissue pressure, instability of optical signals for adaptive stimulation, and extended recharge times.
Innovation Solution
The improved IPG design incorporates a non-metallic case for reduced corrosion, a super ellipse curve for reduced erosion risk, stable optical signal transmission through precise lead and optical fiber coupling, and continuous charging duty cycles to minimize recharge time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic case is used in the IPG, then structural strength is improved, but corrosion resistance deteriorates in the harsh in vivo environment
Solution Approach 1:
The patent employs a hermetic seal construction that combines a metallic canister (for structural strength) with a hermetic barrier layer (for corrosion resistance). This composite approach allows the device to maintain mechanical integrity while protecting internal components from corrosive bodily fluids, resolving the contradiction between strength and corrosion resistance.
2Ease of manufacture
If the IPG has a standard circular shape, then manufacturing is simplified, but device erosion due to tissue pressure increases
Solution Approach 1:
The patent modifies the IPG housing geometry from a standard circular cross-section to an ellipse with specific aspect ratios. This curved, non-circular shape distributes tissue pressure more evenly across the device surface, reducing focal points of high stress that cause erosion. The elliptical geometry maintains manufacturability while significantly improving erosion resistance.
3Ease of manufacture
If optical fibers are loosely coupled in the lead, then lead manufacturing is easier, but optical signal stability deteriorates
Solution Approach 1:
The patent incorporates optical fibers into the lead assembly during the manufacturing process with pre-established positioning features and coupling mechanisms. This preliminary integration ensures precise alignment and stable coupling before implantation, maintaining optical signal stability while preserving manufacturing efficiency through standardized assembly procedures.
4Duration of action of stationary object
If the IPG uses interrupted charging cycles, then battery longevity is improved, but recharge time increases
Solution Approach 1:
The patent enables continuous inductive charging through the IPG housing by using a non-metallic (e.g., ceramic or polymer) material for the housing. This eliminates eddy current losses that would interrupt charging, allowing continuous power transfer from the external charger to the internal battery, thereby reducing recharge time while maintaining battery longevity through controlled charging rates.
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 enhanced IPG achieves improved longevity by reducing corrosion and erosion, maintains stable optical signals for precise stimulation, and facilitates faster charging, thereby enhancing the effectiveness and durability of spinal cord stimulation systems.
Implementation Method 1
The lead body includes an optical fiber extending along its length. The optical fiber is configured to transmit light into the surrounding tissue and collect light reflected from the spinal cord.
Implementation Method 2
The IPG includes an electromagnetic transmitter and receiver configured to wirelessly transmit and receive signals and power from an external electromagnetic receiver and transmitter, respectively.
Data Source
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.