Implantable Electrodes With Mechanical Hydrogel Anchoring
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Solution Overview
Problem
Implantable electrodes face challenges with in vivo fouling due to protein adsorption, leading to increased impedance and reduced efficacy and battery lifetime, particularly for noble metals where robust covalent bonding of biomaterials is difficult to achieve.
Innovation Solution
Mechanically securing hydrogels to electrodes using anchoring features such as apertures, voids, or surface textures, and employing a non-swellable shell to restrict movement and delamination, allowing for reliable attachment without relying on covalent bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If covalent bonding is used to attach biomaterials to noble metal electrodes, then attachment strength is improved, but manufacturing complexity increases due to the difficulty of achieving robust covalent bonding on noble metals
Solution Approach 1:
The patent introduces an intermediary approach by using mechanical anchoring features (apertures, voids, textures) as a mediator between the hydrogel and noble metal electrode. This mechanical interface serves as the bonding mechanism, eliminating the need for complex covalent bonding chemistry on noble metal surfaces while achieving secure attachment.
Solution Approach 2:
The patent replaces the chemical bonding system (covalent bonding) with a mechanical bonding system (physical anchoring through apertures, voids, or surface textures). This substitution leverages the mechanical properties of the electrode structure to achieve secure hydrogel attachment without requiring complex chemical surface modification of noble metals.
2Reliability
If hydrogels are secured using covalent bonding, then reliability of attachment is improved, but device complexity increases due to additional coating and bonding steps
Solution Approach 1:
The patent replaces complex chemical bonding processes with a simpler mechanical anchoring system. The apertures, voids, or surface textures provide inherent mechanical retention for the hydrogel, eliminating the need for additional coating steps and complex bonding protocols while ensuring reliable attachment.
Solution Approach 2:
The anchoring features (apertures, voids, textures) are pre-formed into the electrode structure before hydrogel application. This preliminary structuring creates built-in mechanical retention mechanisms that automatically secure the hydrogel upon application, eliminating the need for subsequent complex bonding operations.
3Ease of operation
If protein adsorption occurs on electrode surfaces, then initial biofunctionality is achieved, but harmful fibrotic tissue deposition increases over time
Solution Approach 1:
The patent applies local quality by creating specific regions with different properties: the hydrogel-coated regions provide protein resistance and biocompatibility, while the conductive metal regions maintain electrical functionality. The anchoring features create localized zones where mechanical interlocking occurs, allowing the hydrogel to conformally coat the electrode surface and provide localized protection against fibrotic encapsulation.
Data Source
AI summary
Biomaterials, such as hydrogels, can be mechanically secured to an electrode of an implantable device using a non-swellable shell. Hydrogel can be applied to an electrode surface and then mechanically constrained in place by a non-swellable shell. The non-swellable material can be secured to a substrate supporting an electrode or can otherwise surround an electrode and the hydrogel. The non-swellable shell can include openings or passthroughs that allow for electrical conduction across the non-swellable shell. The hydrogel can extend out of the openings to contact adjacent biological tissue. In some cases, an outer layer of hydrogel can surround the non-swellable shell and connected to the inner layer of hydrogel through the openings of the non-swellable shell.