Conformable neural interface device with hydrogel adhesion and methods of using the same

Inventors

Horn, Charles C. • Xiao, Gutian • Bettinger, Christopher J. • Fedder, Gary Keith • Ong, Xiao Chuan • Huang, Wei-Chen • Fisher, Lee Erik Bartholomew • Gaunt, Robert A.

Abstract

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.

Core Innovation

The invention provides a conformable neural interface system that interfaces with a nerve using a neural interface device having a probe region with at least one electrode on a nerve-facing surface. The probe region includes conductive traces electrically coupled to the electrode and at least one insulating polymer layer overlying the conductive trace. The system maintains the electrode in non-penetrating contact with the nerve by using an anchor device rather than penetrating nerve tissue or requiring continuous pressure.

The anchor device comprises an elongated adhesive hydrogel layer configured to be wrapped around the nerve with opposing portions of the elongated adhesive hydrogel contacting and adhering to each other. The adhesive hydrogel layer includes a gel polymer network with a crosslinkable polymer precursor crosslinked with a redox active metal or crosslinked polymer/crosslinkable polymer precursor crosslinked with a metal ion. In use, the hydrogel is configured to secure the probe region such that the electrode is maintained in non-penetrating contact with the nerve.

The invention further integrates device compliance and electrode positioning into the conformable system. The probe region is configured to be more compliant than the connector region, with a difference in compliance provided at least in part by a difference in material composition or structure between the two regions. The system also includes configurations where the electrode is maintained with a constrained separation from the nerve-facing surface, including a separation of no more than 25 nm as a limiting feature.

Claims Coverage

The independent claims are clm-00001, clm-00015, and clm-00027. Together they cover three inventive features: non-penetrating electrode-nerve contact secured by an elongated adhesive hydrogel anchor, direct bonding of the adhesive hydrogel to a nerve-facing probe surface that at least partially surrounds the electrode, and compliance tuning in which the probe region is more compliant than the connector region.

Across the independent claims, the inventive coverage centers on securing a nerve-facing electrode in non-penetrating contact using an adhesive hydrogel anchor with a redox-crosslinked gel polymer network, optionally bonded directly to the probe surface and arranged to hold the electrode. The claims also incorporate compliance tuning by requiring the probe region to be more compliant than the connector region via differences in material composition or structure.

Stated Advantages

Documented Applications