Flexible SiC Neural Interface for Biocompatible Brain Implants
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Solution Overview
Problem
Existing implantable neural devices face challenges with biocompatibility, high manufacturing costs, and performance issues, particularly due to the use of silicon and silicon oxide, which are non-biocompatible and require high-temperature manufacturing techniques.
Innovation Solution
The use of polycrystalline silicon carbide (SiC) at low manufacturing temperatures, combined with amorphous SiC for insulation, to create a flexible, monolithic neural interface device suitable for both surface and implantable applications, utilizing in-situ doping, laser doping, or wafer bonding methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon and silicon oxide are used in neural devices, then manufacturing is easier and cost is lower, but biocompatibility deteriorates and devices fail for long-term implantation
Solution Approach 1:
The patent changes the material composition from silicon/silicon oxide to silicon carbide, fundamentally altering the chemical and physical parameters to achieve both biocompatibility and manufacturability. This material substitution resolves the contradiction by providing a substance that is both biocompatible and compatible with standard semiconductor manufacturing processes.
Solution Approach 2:
The invention uses composite material structures including doped and undoped silicon carbide layers, metal contacts, and insulating layers to create a neural device that achieves both biocompatibility and functional performance. The multi-layer composite structure allows optimization of each layer for specific functions while maintaining overall biocompatibility.
2Reliability
If crystalline silicon carbide is used for biocompatible implants, then biocompatibility improves, but manufacturing cost increases due to high-temperature techniques and expensive substrates
Solution Approach 1:
The patent employs inexpensive silicon substrates instead of expensive crystalline silicon carbide substrates. The silicon substrate serves as a temporary support during manufacturing that can be removed, allowing the use of cheap starting materials while achieving the desired biocompatible silicon carbide structure in the final device.
Solution Approach 2:
The invention performs preliminary formation of silicon carbide layers on silicon substrates using low-cost, low-temperature techniques before final device assembly. This preliminary action allows the use of inexpensive materials and processes that would not be suitable for direct fabrication of the final biocompatible device.
3Ease of manufacture
If cubic SiC is used for implants, then manufacturing cost decreases using Si substrates and SOI technology, but breakdown voltage deteriorates due to low voltage of required diode junction layers
Solution Approach 1:
The patent changes the crystal structure parameter from cubic SiC to hexagonal SiC (4H-SiC or 6H-SiC), which fundamentally alters the electrical properties including breakdown voltage. This parameter change resolves the contradiction by providing higher breakdown voltage while maintaining compatibility with silicon substrate manufacturing.
Solution Approach 2:
The invention creates a composite structure with doped and undoped silicon carbide layers, where the doped layers provide electrical functionality and the undoped layers provide high-breakdown-voltage isolation. This composite approach achieves both low manufacturing cost and high reliability.
4Reliability
If field effect devices are used for neural interaction, then electrical impedance is high for influencing electrochemical environment, but long-term performance deteriorates due to sodium ion diffusion and non-biocompatibility
Solution Approach 1:
The patent changes the material composition from silicon/silicon oxide to silicon carbide, which fundamentally alters the chemical stability and electrical properties. This parameter change resolves the contradiction by providing a material that maintains high electrical impedance performance while being chemically stable and biocompatible for long-term implantation.
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 provides a cost-effective, flexible, and biocompatible neural interface capable of long-term neural signal transduction, enabling applications such as brain-machine interfaces for treating conditions like Parkinson's and neural damage.
Implementation Method 1
The present invention utilizes polycrystalline SiC, formed at low manufacturing temperatures and using either in-situ or laser dopant activation
Implementation Method 2
formed at low manufacturing temperatures and using either in-situ or laser dopant activation
Data Source
AI summary
An implantable, conformal, neural interface device fabricated completely from neuro-compatible SiC and method of manufacture thereof, includes at least one elongated probe to be placed in a brain of a subject of interest, the at least one elongated probe comprising a plurality of electrodes positioned on a surface of the elongated probe, each of the plurality of electrodes comprising a conductive mesa consisting of polycrystalline silicon carbide (SiC), an insulative layer consisting of amorphous SiC, the insulative layer positioned to surround the conductive mesa absent a window through the amorphous SiC exposing a surface of the conductive mesa. The elongated probe is integral with, the probe base comprising a plurality of contact pads, each of the plurality of contact pads in electrical communication with one of the plurality of electrodes.