Nerve Interface Electrode with Dynamic Polymer Fibers
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Solution Overview
Problem
Existing nerve interfaces struggle with selective activation and recording of nerve signals, particularly in activating or recording smaller groups or individual fascicles with minimal activation of non-synergistic muscle groups, due to limited precision and flexibility in electrode design.
Innovation Solution
A nerve interface electrode comprising conductive fibers with a nonconductive sheath and a polymer material that switches from high to low tensile modulus upon insertion, allowing the fibers to be rigid for insertion and flexible within the nerve for precise stimulation and recording between fascicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional nerve electrodes are used, then electrode insertion is straightforward, but selective activation of individual fascicles cannot be achieved
Solution Approach 1:
The electrode is segmented into multiple independent conductive fibers (e.g., 12 fibers) that can be individually controlled. Each fiber can be inserted between specific fascicles and activated independently, enabling selective stimulation of individual fascicles while leaving others unaffected. This segmentation transforms a monolithic electrode into a distributed array of controllable elements.
Solution Approach 2:
Different regions of the nerve are targeted with different fiber configurations. The electrode design allows local placement of conductive fibers between specific fascicles based on the functional requirements of each region. This enables fascicle-specific activation in different areas of the nerve without affecting other regions.
2Ease of operation
If rigid fibers are used for insertion, then insertion through epineurium is easier, but fiber flexibility within the nerve is reduced
Solution Approach 1:
The fiber properties are made dynamic by incorporating a shape-memory polymer coating that responds to temperature changes. During insertion, the polymer is in a rigid state (below transition temperature), facilitating easy penetration through the epineurium. After insertion and body heating, the polymer transitions to a flexible state (above transition temperature), allowing the fibers to adapt to the nerve's flexion and movement.
Solution Approach 2:
The physical state of the polymer coating is changed by temperature parameter variation. The transition temperature of the shape-memory polymer is designed to be below body temperature, automatically triggering the phase transition from rigid to flexible state after insertion. This parameter change enables the fiber to adapt its mechanical properties to different operational phases.
3Measurement precision
If multiple fibers are inserted into the nerve, then selective activation capability is improved, but trauma to the nerve increases
Solution Approach 1:
Each conductive fiber is coated with a flexible polymer sheath (e.g., polyethylene terephthalate) that is soft and compliant. This thin film coating reduces mechanical trauma to the nerve by allowing the fiber to flex and move with the nerve tissue rather than creating rigid foreign bodies. The flexible coating also facilitates smooth insertion through the epineurium.
Solution Approach 2:
The dynamic flexibility of the polymer-coated fibers allows them to adapt to nerve movement and flexion. The shape-memory polymer transitions from rigid during insertion to flexible during operation, enabling the multi-fiber array to move collectively with the nerve without creating persistent mechanical stress or trauma points.
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 solution enables selective and precise activation and recording of nerve signals, minimizing trauma to the nerve and achieving targeted muscle activation with improved selectivity and control over fascicular electrical activity.
Implementation Method 1
The fibers may be configured with a shape memory polymer coating that switches from a rigid state to a flexible state in response to body temperature or other stimuli.
Implementation Method 2
a layer of polymer material configured to switch from a high strength/tensile modulus state to a low strength/tensile modulus state upon introduction of the fibers into the nerve
Data Source
AI summary
A nerve interface electrode has a plurality of conductive fibers. The fibers have a nonconductive sheath (108) surrounding a conducting wire. A conducting region (105) of the wire is exposed to the interior of the nerve (200). The fibers are configured for insertion between fascicles (204) of the nerve. In other teachings, a layer of polymer material configured to switch from a high strength/tensile modulus state to a low strength/tensile modulus state upon introduction of the fibers into the nerve is disposed on the fibers.