Ceramic Implant Feedthrough With Ferrule Bonding for Biocompatible Connection
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Solution Overview
Problem
The challenge of forming reliable biocompatible electrical connections in implantable devices is exacerbated by the toughness of via materials and the lack of biocompatible soldering materials, leading to poor or no connections and carbonized soot, which complicates the welding process.
Innovation Solution
The use of biocompatible materials like gold/platinum traces and platinum-iridium ferrules, combined with laser welding, to create electrical connections through ceramic substrates, ensuring a robust and clean connection without the need for drilling vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding methods (silver epoxy, sintering, eutectic bonding) are used to connect metal leads to ceramic substrates, then electrical connection is achieved, but biocompatibility is compromised due to nickel content and toxic flux residues
Solution Approach 1:
The patent extracts and removes harmful nickel content from the bonding process by using nickel-free alloys (such as cobalt-chromium or palladium-based alloys) for both the metal leads and bonding wires. This extraction of the toxic element eliminates the biocompatibility issue while maintaining the electrical connection function.
Solution Approach 2:
The patent changes the material parameters by transitioning from traditional silver epoxy or sintering bonds to direct metal-to-metal bonding using nickel-free alloys. This parameter change in material composition enables biocompatibility without requiring complex multi-step bonding processes.
2Strength
If thick metal leads are used to ensure mechanical strength and electrical conductivity, then structural integrity is improved, but the device size increases preventing miniaturization
Solution Approach 1:
The patent employs composite material structures where thin metal leads are reinforced through direct metal-to-metal bonding with bonding wires made of nickel-free alloys. This composite approach creates a strengthened connection that maintains mechanical integrity while allowing the leads themselves to remain thin for miniaturization.
Solution Approach 2:
The patent segments the electrical connection function into separate components: thin metal leads for signal transmission and separate bonding wires for mechanical reinforcement and electrical connection to the ceramic substrate. This segmentation allows each component to be optimized independently - leads remain thin while bonding wires provide strength.
3Reliability
If traditional bonding processes are used, then electrical connection is established, but harmful flux residues and nickel leaching occur causing tissue damage
Solution Approach 1:
The patent converts the potential harm of metal bonding by using nickel-free alloys that are biocompatible. The direct metal-to-metal bonding process, which could potentially leave residues, is made beneficial by using materials that do not leach toxic substances, turning a potentially harmful process into a safe one for implantable applications.
Solution Approach 2:
The patent creates a biocompatible environment by using nickel-free alloys that resist corrosion and do not leach toxic ions into the surrounding tissue. This inert, non-reactive material environment prevents harmful chemical interactions with body tissues while maintaining electrical conductivity.
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
This method enables reliable biocompatible electrical connections in implantable devices, maintaining high electrical conductivity and cleanliness while simplifying the manufacturing process.
Implementation Method 1
a nickel-free alloy bonding wire is used to bond the metal lead to a pad on the ceramic substrate
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
A biocompatible electrical connection includes: a substrate; a ferrule having a concentric flange at a first end of the ferrule; a first adhesive; and a second adhesive. The substrate includes a hole having a diameter that is a specified amount larger than an outside diameter of the ferrule forming an annular space between the hole and the ferrule, the first adhesive adheres a first surface of the concentric flange of the ferrule to a first surface of the substrate, and the second adhesive fills the annular space between the hole and the ferrule.