Flexible Microelectrode Array with Zigzag Traces
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Solution Overview
Problem
Existing microelectrode arrays for implantable medical devices lack flexibility and stretchability, with materials like silicon and polyamide being non-compliant, and electroplated platinum prone to cracking, while producing high-quality thick Pt electrodes on silicone substrates is challenging, limiting their suitability for current medical applications.
Innovation Solution
A method involving micromachining techniques combines biocompatible polymeric layers with patterned metallic traces and electrodes, featuring a zigzag configuration and rounded corners, similar to metal stents, to create a flexible and stretchable microelectrode array that can be safely implanted within living tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon or polyamide substrates are used for microelectrode arrays, then micromachining processes can be applied, but the arrays lack flexibility and stretchability
Solution Approach 1:
The patent changes the substrate material from rigid silicon or polyamide to flexible silicone rubber, fundamentally altering the mechanical properties to enable stretching and conformability while maintaining micromachining compatibility through careful process design
Solution Approach 2:
The patent creates a composite structure combining silicone substrate with metal traces and electrodes, where each material contributes its optimal properties: silicone provides flexibility and biocompatibility, while metal provides electrical conductivity and structural integrity
2Reliability
If electroplated platinum is used for traces and electrodes, then conductive features can be formed, but cracking and delamination occur due to large residual stresses
Solution Approach 1:
The patent changes the trace fabrication method from electroplating to direct deposition or lamination of flexible metallic materials, eliminating the residual stress problem inherent in electroplating while maintaining electrical conductivity
Solution Approach 2:
The patent employs thin flexible metallic traces and electrodes that can bend and stretch with the substrate, preventing the cracking and delamination that occurs with rigid electroplated structures
3Adaptability or versatility
If thin film gold traces are used, then flexibility is improved, but the traces are not acceptable for implantable medical devices
Solution Approach 1:
The patent combines biocompatible silicone substrate with medically acceptable metal traces and electrodes, creating a composite structure that satisfies both flexibility requirements and implantable device standards
Solution Approach 2:
The patent changes the trace material from thin film gold to flexible metallic traces with appropriate thickness and composition that meet both mechanical flexibility requirements and biocompatibility standards for implantable devices
4Ease of manufacture
If standard deposition techniques are used on silicone substrates, then fabrication can be simplified, but producing high quality thick Pt electrodes is extremely challenging
Solution Approach 1:
The patent changes the electrode fabrication approach to accommodate the flexible silicone substrate, using deposition and lamination techniques optimized for polymer surfaces rather than traditional rigid substrate methods
Solution Approach 2:
The patent introduces intermediate processing steps and specialized techniques as mediators between the silicone substrate and metal electrode deposition, enabling high-quality electrode formation on flexible surfaces
Data Source
Figure 1A~1C
Figure 1D~1E
Figure 2
AI summary
A high-density microelectrode array includes at least first and second implantable and biocompatible polymeric layers in which a plurality of patterned conductive features, including metallic contact pads, metallic traces and metallic electrodes are sandwiched between them. Each metallic trace is located between a metallic contact pad and a metallic electrode and has substantially rounded corners and a zigzag pattern.