Neural interface device manufacturing method
Inventors
Gardner, Timothy James • Cogan, Stuart F.
Assignees
Boston University • University of Texas System
Publication Number
US-12193821-B2
Publication Date
2025-01-14
Expiration Date
2038-06-22
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Abstract
Manufacturing a neural interface device. Forming a neural interface probe of an implantable microelectrode body. PECVD a first amorphous silicon carbide insulation layer, forming a thin film metal trace and interface pad on the first layer, the pad on a portion of the trace. PECVD a second amorphous silicon carbide insulation layer on the first layer and covering the trace and the pad. Forming an opening in the second layer to expose the pad to an ambient environment. Patterning the first and second layers to define the neural interface probe. The probe has a rectangular cuboid shape, a cross-sectional area perpendicularly transverse to a long axis length of the probe and through any perpendicularly transverse cross-section along the long axis length is less than about 50 microns. The layers are the principle material of construction of the probe.
Core Innovation
The invention relates to the manufacturing of neural interface devices consisting primarily of implantable microelectrode bodies. The neural interface probe within these devices comprises thin film metal traces connected to interface pads, all encapsulated by amorphous silicon carbide (a-SiC) insulation. The a-SiC material forms the principal structural component, with the probe shaped as a rectangular cuboid and having cross-sectional areas less than about 50 microns square along its length. Openings in the a-SiC encapsulation expose the interface pads to the surrounding environment, allowing electrical connection with neural tissue.
The core problem addressed by the invention is the limitation of previously existing microelectrode arrays, which often experience diminished performance due to encapsulation by reactive tissue responses and corrosion from biological fluids. Existing solutions either lack chronic stability, exhibit increased foreign body response, or their insulating materials do not provide a sufficient barrier against biological fluids, leading to loss of neural signal quality and viability.
This invention introduces a manufacturing method utilizing plasma enhanced chemical vapor deposition (PECVD) to form layered a-SiC insulation, which surrounds and protects thin film metal circuitry within the neural probes. The process precisely controls residual stresses and maintains dimensional tolerances, enabling the production of extremely small, planar, and mechanically robust probes resistant to buckling. The structural geometry, with a high proportion of a-SiC and a small cross-section, minimizes foreign body response while still allowing for effective penetration into neural tissue and chronic functionality.
Claims Coverage
There is one independent claim in this patent, from which several dependent claims follow. The independent claim centers on the specific method of manufacturing neural interface devices with stated material compositions and structural specifications.
Method of manufacturing neural interface device comprising a-SiC layered structure with embedded metal trace
The method includes: 1. Forming one or more neural interface probes on an implantable microelectrode body. 2. Depositing a first amorphous silicon carbide insulation layer on a release layer using plasma enhanced chemical vapor deposition. 3. Forming a photoresist layer, patterning it to expose portions of the first a-SiC, and depositing a metal layer to create a thin film metal trace on the first a-SiC, then removing excess metal/photoresist. 4. Depositing a second a-SiC insulation layer over the structure by PECVD, fully covering the thin film metal trace. 5. Creating openings in the second a-SiC layer to expose portions of the thin film metal trace, defining interface pads accessible to the ambient environment. 6. Patterning the first and second a-SiC insulation layers to define the neural interface probe(s), ensuring: - The cross-sectional area perpendicular to the long axis at any point is less than 100 microns², - At least 85 percent of each cross-sectional area is composed of the first and second a-SiC layers as the principal material of construction.
The inventive features define a manufacturing process yielding neural interface probes with ultra-small dimensions, high a-SiC content, encapsulated metal traces, and selective exposure of interface pads, all implemented through specific layered deposition and patterning steps.
Stated Advantages
The use of amorphous silicon carbide as the principal material allows probes with small enough cross-sectional area to minimize foreign body response, while also providing sufficient buckling resistance for reliable implantation.
An a-SiC outer surface serves as a highly effective barrier against biological fluids, protecting thin film metal traces from corrosion and thereby maintaining stable device performance.
The rectangular cross-section geometry achieves higher buckling resistance than circular counterparts for equivalent minimum dimension, enabling smaller and less traumatic implants.
Controlling residual stresses in the a-SiC layers and metal traces maintains planarity, reducing unwanted probe deflection and tissue damage during implantation.
Device configurations with a plurality of neural interface probes enable increased contact points and flexible spatial distribution for improved neural recording or stimulation.
The manufacturing approach enables the formation of probe bundles that enhance penetration into tissue and minimize buckling during implantation due to van der Waals bonding.
Documented Applications
Implantation into neural tissue for chronic recording of electrical neural activity in scientific studies of neural circuit function.
Clinical applications such as brain-machine and brain-computer interfaces requiring robust, chronically stable recording of extracellular neural activity.
Clinical delivery of therapeutic electrical stimulation using stimulating microelectrode arrays implanted in neural tissue.
Implantation in peripheral nerves and deep brain structures, including devices with probe lengths suited for each application.
Multi-dimensional neural interfacing by stacking pluralities of these devices with spacers to cover three-dimensional tissue volumes.
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