Hermetic Implantable Sensor Conductor Porosity Reduction
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Solution Overview
Problem
Designing implantable sensors that require a hermetic seal to prevent signal degradation and failures, while being compact and biocompatible, is challenging due to issues with electrode and conductor construction, leading to inaccuracies and infections.
Innovation Solution
A sensor with a substrate made of high-temperature resistant insulating material, where electrically conductive thick film material is sintered to reduce porosity and then coated with an insulating material to create a hermetic seal, leaving exposed regions for detection electrodes, preventing fluid migration and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode and conductor construction is used in implantable sensors, then the device can be fabricated with standard techniques, but the hermetic seal fails leading to signal degradation and device failure
Solution Approach 1:
The patent changes the physical parameters of the conductor by sintering the thick film material at high temperature to reduce porosity from a porous state to a dense state. This parameter change (porosity reduction) enables the conductor to provide hermetic sealing without requiring additional sealing structures, thus improving reliability while managing complexity
Solution Approach 2:
The patent uses composite material structure where the conductor is formed from thick film material containing metal particles in a glass matrix. This composite structure allows the conductor to simultaneously provide electrical conductivity and hermetic sealing when sintered, resolving the contradiction between seal integrity and construction complexity
2Ease of manufacture
If the conductor is made porous to facilitate fabrication, then manufacturing is easier, but fluid migration through the conductor causes corrosion and failure
Solution Approach 1:
The patent applies parameter change by controlling the porosity of the thick film conductor through sintering temperature and duration. The conductor transitions from a porous unfired state (easy to manufacture) to a dense fired state (resistant to fluid migration). This parameter transformation resolves the contradiction between ease of manufacture and reliability
Solution Approach 2:
The sintering process induces a phase transition in the thick film material where metal particles coalesce and the glass matrix densifies, transforming the conductor from a porous green state to a dense ceramic state. This phase transition enables the conductor to achieve hermetic properties while maintaining fabrication simplicity
3Ease of manufacture
If the insulating coating is applied before sintering, then the coating process is simpler, but the coating cracks during sintering compromising the hermetic seal
Solution Approach 1:
The patent applies preliminary action by performing the sintering process before applying the insulating coating. This sequence ensures the conductor is already dense and dimensionally stable when coated, preventing coating cracks and maintaining hermetic seal integrity while keeping the coating process simple
4Ease of operation
If wires extend through the skin for external connection, then electrical connection is simpler, but infection risk increases and comfort decreases
Solution Approach 1:
The patent extracts the wire penetration function by providing exposed regions of the conductor that extend through the insulating coating to form external connection points. This allows electrical connection without wires penetrating the skin, eliminating infection risk while maintaining connection ease
Solution Approach 2:
The insulating coating acts as a hermetic barrier shell that encapsulates the conductor while providing exposed regions for connection. This thin film barrier prevents fluid ingress and infection while allowing electrical access, resolving the contradiction between connection ease and infection prevention
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 minimizes failures and inaccuracies by inhibiting fluid and gas migration through the conductors, ensuring a reliable and accurate hermetic seal for implantable devices, even when exposed to bodily fluids.
Implementation Method 1
heating the electrically conductive thick film material to a first predetermined temperature, below a second predetermined melting temperature thereof, which is sufficient to sinter a plurality of metal particles in the electrically conductive thick film material
Implementation Method 2
A coating made of a second insulating material is formed over the substrate to hermetically seal at least a portion of the conductor
Data Source
AI summary
At least one conductor is formed at a preselected location on a substrate made of a first insulating material having a high temperature resistance. The conductor is made from a solidified electrically conductive thick film material. A coating made of a second insulating material is formed over the substrate to hermetically seal at least a portion of the conductor. An exposed distal region of the conductor provides a detection electrode. The conductor has a reduced porosity that inhibits migration of fluid or constituents thereof through the conductor.