Stretchable Neural Interface with Composite Conductive Paths
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Solution Overview
Problem
Current implantable devices for neural interfaces face challenges in achieving chronic bio-integration due to a substantial biomechanical mismatch with neural tissues and inadequate mimicry of the mechanical properties of biological membranes, leading to adverse biological reactions and limited durability.
Innovation Solution
Development of a new class of soft multimodal neural interface devices, such as e-dura, which mimics the topology and compliance of the dura mater, incorporating stretchable gold or chromium interconnects, soft platinum-silicone composite electrodes, and microfluidic channels to achieve chronic bio-integration and support multiple neuroprosthetic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rigid implantable devices are used, then electrical functionality is maintained, but biomechanical mismatch with neural tissues occurs leading to adverse biological reactions
Solution Approach 1:
The patent employs flexible and stretchable materials including silicone rubber substrates, thin metal interconnect layers, and elastic conductive polymers to create an implantable device that can deform with neural tissues. This flexibility eliminates the biomechanical mismatch between rigid traditional devices and soft neural tissues, preventing adverse biological reactions while maintaining electrical functionality through the conductive components.
Solution Approach 2:
The device integrates multiple materials with complementary properties: silicone rubber provides mechanical flexibility and biocompatibility, thin metal layers (gold, chromium) provide electrical conductivity, and conductive polymers add stretchability. This composite structure resolves the contradiction by combining the mechanical compliance needed to match neural tissues with the electrical functionality required for neural interfacing.
2Object-affected harmful factors
If stretchable materials are used to match tissue compliance, then biocompatibility improves, but electrical conductivity and impedance stability may deteriorate
Solution Approach 1:
The patent uses composite structures where conductive elements are embedded within or deposited on flexible substrates. Thin metal interconnect layers are patterned on silicone rubber, and conductive polymers are integrated to provide both stretchability and electrical pathways. This composite approach maintains electrical conductivity while allowing the overall device to stretch and conform to neural tissues.
Solution Approach 2:
The device exhibits local quality differentiation: regions with metal interconnects and electrodes provide high electrical conductivity for signal transmission, while the surrounding silicone rubber substrate provides mechanical flexibility and stretchability. This spatial variation in material properties allows the device to simultaneously achieve biocompatibility through tissue-matching compliance and electrical reliability through localized conductive pathways.
3Shape
If device thickness is reduced to match biological membrane properties, then conformability to curvilinear surfaces improves, but mechanical strength and durability may worsen
Solution Approach 1:
The patent utilizes thin film structures where metal interconnects are deposited as thin layers (e.g., 50-100 nm gold, 10-20 nm chromium) on flexible silicone rubber substrates. These thin films conform to curvilinear neural tissue surfaces while the flexible substrate provides the mechanical strength and tear resistance needed for durability during implantation and chronic use.
Solution Approach 2:
The composite structure combines thin conductive metal films with a thicker flexible polymer substrate. The thin metal layers provide electrical functionality and conformability to surfaces, while the bulk silicone rubber substrate provides mechanical strength, elasticity, and resistance to fracture. This division of functional roles between thin and thick components resolves the contradiction between conformability and strength.
4Duration of action of stationary object
If device is designed to withstand mechanical deformations, then durability improves, but complexity of integrating multiple functions (electrical, fluidic, optical) increases
Solution Approach 1:
The patent merges multiple functional components into a single integrated flexible device structure. Electrical interconnects, fluidic channels, and optical elements are all incorporated into the same silicone rubber substrate with shared mechanical properties. This unified design allows the entire device to deform together as one unit, withstanding mechanical stresses while providing multiple functions without requiring separate rigid components that would complicate integration.
Solution Approach 2:
The flexible substrate serves as a common platform for all device components, providing a unified mechanical envelope that protects and integrates electrical traces, fluidic pathways, and optical elements. This flexible shell approach simplifies the integration of multiple functions by allowing all components to be fabricated and assembled on the same compliant substrate, which naturally accommodates thermal expansion and mechanical deformation without requiring complex stress management for each individual component.
Data Source
AI summary
A method produces a device adapted to be implanted into the human body for purposes such as neural stimulation, sensing or the like. The method includes: providing a stretchable layer or membrane of an insulating material; forming on the layer or membrane at least one stretchable conductive path; depositing at least one small bolus of a soft and conductive paste or material onto pre-defined areas or portions of the at least one conductive path, and inserting a first end portion of a conductive element 71 into the at least one bolus of soft conductive paste or material. A second end portion of the conductive element opposite to the first end portion is not inserted into the at least one bolus.