Implantable Sensor Electronics Packaging with Hermetic Enclosure
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Solution Overview
Problem
Existing implantable sensors face challenges in maintaining biocompatibility and effectively monitoring internal anatomical changes, such as bone healing, due to corrosion and liquid ingress issues, which affect the accuracy and longevity of strain gauge measurements.
Innovation Solution
A hermetically sealed implantable sensor module with a flexible circuit board assembly and strain gauges external to a sealed enclosure, powered by a received magnetic field, ensuring biocompatibility and preventing corrosion, while allowing for long-term monitoring of mechanical parameters like bone healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to an orthopedic implant for long-term monitoring, then measurement capability is improved, but corrosion and liquid ingress degrade reliability over time
Solution Approach 1:
The sensor system is divided into separate functional components: strain gauges are mounted on the orthopedic implant exterior for measurement, while electronics are housed in a separate hermetically sealed enclosure. This segmentation allows the measurement elements to remain exposed to mechanical loads while protecting sensitive electronics from corrosion and liquid ingress, resolving the contradiction between measurement accessibility and reliability.
Solution Approach 2:
A hermetically sealed enclosure acts as an intermediary barrier between the electronic components and the corrosive bodily environment. This sealed enclosure with hermetic seal prevents liquid ingress and corrosion while allowing electrical connection through the wall, thereby protecting reliability without compromising measurement capability.
2Reliability
If strain gauges are placed inside a sealed enclosure for protection, then reliability is improved, but access to mechanical parameters deteriorates
Solution Approach 1:
The system segments measurement functions from electronic processing functions. Strain gauges remain externally mounted on the orthopedic implant where they directly experience mechanical loads for accurate measurement, while only the electronics are enclosed for protection. This resolves the contradiction by protecting only what needs protection while leaving measurement elements accessible.
Solution Approach 2:
The measurement-critical strain gauges are extracted from the sealed enclosure and placed on the external surface of the orthopedic implant, while only the non-measuring electronic components remain inside the protective enclosure. This extraction allows the measurement elements to maintain direct contact with mechanical parameters while electronics gain corrosion protection.
3Reliability
If hermetic sealing is implemented to prevent corrosion, then reliability is improved, but device complexity increases
Solution Approach 1:
A hermetically sealed enclosure serves as an intermediary protective barrier that isolates electronic components from the corrosive bodily environment. This single sealed structure provides comprehensive corrosion protection for all internal electronics without requiring individual protection for each component, managing complexity through a unified sealing approach.
Solution Approach 2:
The hermetically sealed enclosure provides self-contained protection for the electronic components, requiring no external maintenance or intervention to prevent corrosion. The sealed design inherently prevents liquid ingress and corrosion without additional active protection systems, reducing operational complexity while maintaining reliability.
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 provides reliable, long-term monitoring of bone healing by maintaining sensor integrity and accuracy through biocompatibility and corrosion protection, enabling effective communication of mechanical parameter changes to external devices.
Implementation Method 1
the sealed enclosure is hermetic and/or has a near-hermetic barrier quality, such as may be provided by different types of glass, quartz, or metal
Implementation Method 2
the transducer is a strain gauge operative to measure an amount of elastic strain present in the substrate
Implementation Method 3
the FCBA is held apart from the enclosure via a polymeric spacer provided therebetween
Implementation Method 4
an inert polymer fill may be provided within the sensor volume external to the enclosure as an additional means of sealing the sensor
Data Source
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AI summary
An implantable device includes a substrate and protective cover that cooperate to define an enclosed sensor volume. A sealed enclosure is provided within the sensor volume, with an electronic component assembly (ECA) being located within the sealed enclosure. A flexible circuit board assembly (FCBA) is electrically coupled with the ECA through a wall of the sealed enclosure. At least one transducer is provided on the FCBA in contact with the substrate, and the FCBA is held apart from the enclosure via a polymeric spacer provided therebetween. An inert polymer fill is provided within the sensor volume external to the enclosure.