Cochlear Implant Feedthrough Segmentation
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Solution Overview
Problem
The manufacturing of implantable medical devices with titanium or ceramic housings faces challenges such as complex machining of small holes, high costs, and poor adhesion of metals like platinum to conductive epoxy, which complicates the assembly of feedthrough elements for hermetically sealed enclosures.
Innovation Solution
A cochlear implant design featuring a ceramic upper cover with a circumferential flange and feedthrough elements with a plate-shaped base, hermetically joined to a titanium lower cover, utilizing laser welding for assembly and silicone overmolding to protect leads, allowing for efficient manufacturing and routing of electrodes through a void between the device and tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium housing is used with feedthroughs assembled into the main body, then hermetic seal integrity is improved, but manufacturing complexity increases due to large number of welds required
Solution Approach 1:
The housing is divided into two separate components: a titanium housing and a ceramic feedthrough assembly. The feedthrough is inserted into the titanium housing and secured with minimal welding (only at the flange connection), rather than assembling multiple feedthroughs directly into the main titanium body. This segmentation reduces the number of welds from at least one per feedthrough to just a few at the flange connection points.
2Reliability
If feedthroughs are directly brazed onto titanium body, then hermetic connection is improved, but manufacturing complexity increases due to complex machined titanium part requirements
Solution Approach 1:
The feedthrough is separated from the titanium housing body and manufactured as a distinct ceramic component with its own flange. This allows the titanium housing to be a simpler, less machined part, while the complex feedthrough structure is contained in the removable ceramic assembly that can be prepared separately and installed as a unit.
3Adaptability or versatility
If ceramic housing is used with feedthroughs all around perimeter, then electrical connection capability is improved, but manufacturing cost increases due to machining very small holes in hard material
Solution Approach 1:
Multiple feedthroughs are integrated into a single ceramic feedthrough assembly rather than machining individual holes separately in the housing. The ceramic piece is manufactured as one component with all necessary feedthrough channels and flange features, eliminating the need for multiple separate machining operations on the hard ceramic housing material.
4Reliability
If platinum is used for electrical connection, then electrical conductivity is improved, but adhesion to conductive epoxy deteriorates due to smooth metal surface
Solution Approach 1:
The ceramic feedthrough provides different surface characteristics at different locations: smooth surfaces for electrical contact with platinum conductors, and roughened or chemically treated surfaces (such as silane treatment) for strong adhesion to conductive epoxy. This local differentiation of surface properties allows both good electrical conductivity and strong mechanical adhesion without compromising either property.
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 design simplifies the manufacturing process, reduces material waste, and ensures a high-yield hermetic seal with leak-tested feedthrough elements, while providing a secure and shock-resistant path for electrode leads, facilitating easier implantation and communication with external devices.
Implementation Method 1
utilizing laser welding for assembly
Implementation Method 2
Attaching metal pads on a flexible circuit to metal pads on a hermetic device by conductive adhesive
Implementation Method 3
The document provides a roughened surface, such as etching or applying high surface area platinum gray, to improve adhesion to platinum or other metal pads
Implementation Method 4
silicone overmolding to protect leads
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A cochlear implant includes a sealed housing (201) containing electronics (208) for at least stimulation or collection of data and at least one antenna (310) for communicating with an external device and a magnet (314)configured to hold the external device in proximity to the sealed housing. The sealed housing (201) includes an upper cover (203) being closest to the skin when the device is implanted, and a lower cover (206) that is hermetically connected to the upper cover. The lower cover includes an elevated region (210, 211), a recessed region (220), and at least one feedthrough element (204, 209) formed in the recessed region of the lower cover. The recessed region provides space for a lead to connect to the feedthrough element and protects it from shock and other environmental risks.