Hydrogel Neural Interface Adhesion for Selective Nerve Contact
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Solution Overview
Problem
Existing neural interfaces, particularly extraneural electrodes, lack spatial selectivity and mechanical compliance, leading to inadequate contact with peripheral nerves and ganglia, and are invasive.
Innovation Solution
A suture-like anchor device with a gel polymer network, crosslinked with redox active metals, provides enhanced mechanical compliance and adhesion, allowing for non-invasive yet selective contact with peripheral neural tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If extraneural electrodes are used to reduce invasiveness, then invasiveness is reduced, but spatial selectivity deteriorates due to increased separation from fascicles
Solution Approach 1:
The patent employs a flexible hydrogel substrate that can conform to the curved surface of peripheral nerves, allowing extraneural electrodes to maintain close proximity to fascicles without invasive penetration. The hydrogel's elasticity and compliance enable it to wrap around nerve structures, bridging the gap between non-invasive placement and spatial selectivity requirements.
Solution Approach 2:
The patent utilizes stimuli-responsive polymers within the hydrogel that change their physical or chemical properties in response to environmental cues (such as pH, temperature, or mechanical stress). This allows the electrode array to dynamically adjust its configuration or adhesion properties to optimize contact with specific fascicles while maintaining overall non-invasive positioning.
2Strength
If rigid neural interface devices are used to maintain structural integrity, then structural integrity is improved, but mechanical compliance deteriorates, preventing conformation to peripheral nerves
Solution Approach 1:
The patent creates a composite structure combining a rigid support framework with a compliant hydrogel layer. The rigid substrate provides structural integrity and houses the electrode connections, while the outer hydrogel layer provides mechanical compliance and conformability to nerve surfaces. This multi-layer composite architecture resolves the contradiction between strength and adaptability.
Solution Approach 2:
The hydrogel acts as a flexible shell encapsulating the rigid electrode array, allowing the device to bend and conform to the curvature of peripheral nerves while the internal rigid structure maintains structural integrity. The thin film nature of the hydrogel ensures minimal bulk while providing sufficient compliance.
3Reliability
If mechanical pressure is increased to improve contact with neural tissues, then contact quality is improved, but mechanical pressure on neural tissue increases excessively
Solution Approach 1:
The stimuli-responsive polymers in the hydrogel change their adhesion properties in response to physiological stimuli, allowing the device to optimize contact pressure dynamically. When stimulation or recording is required, the polymer becomes more adhesive to improve contact quality; when not in use, it relaxes to minimize continuous mechanical pressure on the neural tissue.
Solution Approach 2:
The hydrogel's viscoelastic properties allow it to self-adjust its contact pressure with the nerve surface based on local tissue geometry and movement. The material naturally distributes pressure evenly and adapts to nerve pulsations and movements, maintaining reliable contact without requiring excessive external force that would harm the tissue.
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 device achieves enhanced selectivity and mechanical compliance, facilitating better contact with neural tissues without excessive mechanical pressure, enabling effective bioelectrical signal detection and modulation.
Implementation Method 1
the gel polymer network comprises a crosslinkable polymer precursor that is cross linked with a redox active metal
Implementation Method 2
cross linked with a redox active metal
Implementation Method 3
an adhesive hydrogel layer, wherein the electrode contact region is configured to interface with a nerve, ganglion or tissue, and wherein the adhesive hydrogel layer is configured to adhere the electrode contact region to the nerve, ganglion or tissue
Data Source
AI summary
Disclosed are highly compliant bioelectronic neural interface devices with hydrogel adhesion. Example devices include adhesion-promoting functional groups that facilitate enhanced electrical contact with the nerve without the need for continuous application of pressure. A transfer process may be used to fabricate the device using a sacrificial material (e.g., polyacrylic acid (PAA)) that has tunable solubility in aqueous media, helping avoid the need for harsher release chemicals that may affect the properties of the hydrogel. The transfer process also helps achieve electrode contacts that are flush with a surface of the device and facilitate more intimate contact with the nerve. A gradual change in Young's modulus from a stiff contact pad region to a more compliant electrode contact region may be achieved via a varied amount of an epoxy-based material (such as SU-8) and with silicone-based material (such as polydimethylsiloxame (PDMS)) to encapsulate the device cable.