Stealthy Conductor for Targeted Fascicular Neural Interface
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Solution Overview
Problem
Current neural prosthetics face challenges in achieving adequate interfaces with the nervous system due to issues such as low signal-to-noise ratio (SNR), low selectivity, and durability, often causing damage to nerve fibers during interaction, particularly due to the difficulty in penetrating the perineurium and maintaining stability over time.
Innovation Solution
A targeted fascicular interface device with a stealthy conductor, such as a micro-wire or nanowire, is placed longitudinally within a fascicle using a single entry point, minimizing nerve damage by matching the flexibility and properties of the surrounding neuronal material, and using a biocompatible insulator to promote healing and stabilize the device in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-contact cuff electrode surrounds the nerve outside the epineurium, then the interface is stable and safe, but the signal-to-noise ratio is low and selectivity is poor
Solution Approach 1:
The nerve is divided into multiple fascicles, and the electrode is placed selectively within a specific fascicle rather than surrounding the entire nerve. This segmentation allows for focused signal recording from targeted axons while filtering out signals from other fascicles, thereby improving signal-to-noise ratio and selectivity while maintaining stability through precise anatomical targeting.
Solution Approach 2:
The electrode interface is localized to a specific fascicle within the nerve rather than contacting the entire nerve surface. This local placement enables selective recording and stimulation of specific axon populations, improving both signal quality and fascicular selectivity while maintaining mechanical stability through targeted integration with the fascicular structure.
2Measurement precision
If large and stiff electrodes penetrate both the epineurium and perineurium, then the signal-to-noise ratio improves, but the nerve damage increases and individual fascicles cannot be targeted
Solution Approach 1:
The electrode penetration is focused on a single fascicle rather than requiring penetration of the entire nerve covering. By targeting and penetrating only the perineurium of the specific fascicle containing the desired axons, the electrode achieves high signal-to-noise ratio contact while minimizing damage to other fascicles and reducing overall nerve trauma.
Solution Approach 2:
The electrode is designed with localized penetration capability targeting specifically at the perineurium of a chosen fascicle. This localized approach allows the electrode to reach the desired axons for high-quality signal recording while limiting the affected area to a minimal region, thereby reducing overall nerve damage compared to broad penetration methods.
3Ease of manufacture
If unguided penetration is used to reach individual fascicles, then the procedure is simpler, but the electrode may be misplaced without immediate feedback
Solution Approach 1:
The electrode design incorporates immediate feedback mechanisms that allow the surgeon to verify correct fascicular placement during the insertion process. This feedback enables real-time confirmation that the electrode has successfully penetrated the perineurium and reached the target axons, ensuring placement accuracy while maintaining procedural simplicity.
4Ease of manufacture
If conventional electrodes are used, then the interface can be created, but long-term stability is not demonstrated due to wire movement from tethering and shear forces
Solution Approach 1:
The electrode incorporates flexible structures that can accommodate mechanical stresses such as tethering forces and shear forces without displacing from the fascicle. This flexibility allows the electrode to move with the nerve tissue during normal physiological movements, maintaining stable contact with target axons over the long term while preserving the simplicity of the initial interface creation.
Data Source
AI summary
A stealthy conductor that may be placed inside a fascicle in the peripheral nervous system (PNS) is described. The conductor is placed using a targeted-fascicle or targeted-axon approach to improve specificity and signal to noise ratio (SNR). The conductor is part of a targeted fascicular interface device and is placed using an insertion tool in a manner that reduces nerve damage as compared to conventional systems. The conductor is so small (e.g., <10 μm diameter) and so flexible (e.g., approximates flexibility of surrounding neuronal material) that biological reactions (e.g., recruitment of macrophages, edema) to the presence of the conductor may be reduced. The targeted fascicular interface device has an insulated portion and a non-insulated portion that may act as an electrode. The insulated portion may include materials that promote healing at the entry/exit site and that adhere to the perineurium.