Wireless LC Sensor for Hermetic Failure Detection
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Solution Overview
Problem
Conventional methods for testing the hermeticity of implantable medical devices (IMDs) are limited by their destructive, laborious, and costly nature, particularly for small-scale IMDs, and they struggle to accurately measure leak rates in devices smaller than 10−3 cm3.
Innovation Solution
An automated and wireless accelerated heat soak testing system is developed, utilizing a readout coil and an LC sensor with a humidity sensing layer made of magnesium, encapsulated in parylene-C, to monitor hermetic failure through changes in resonance frequency and backscattered signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional leak tests are used to measure hermeticity of IMDs, then leak rate can be measured, but the method is destructive, laborious, and costly especially for small-scale IMDs
Solution Approach 1:
The patent replaces mechanical/wire-based measurement systems with wireless inductive sensing. The IMD contains an LC resonant circuit that wirelessly transmits hermeticity data through inductive coupling, eliminating the need for physical wire tethering and manual measurement operations.
Solution Approach 2:
The IMD performs self-diagnosis of hermeticity using its own LC resonant circuit. The device automatically monitors its own encapsulation integrity and transmits data wirelessly without requiring external measurement equipment or manual intervention at each testing checkpoint.
2Measurement precision
If traditional leak rate tests are used on IMDs with volumes less than 10−3 cm3, then hermeticity can be tested, but the equipment resolution is insufficient to accurately measure leak rates
Solution Approach 1:
The patent changes the measurement parameter from leak rate (which requires high-resolution equipment for small volumes) to resonant frequency shift. The LC circuit's resonant frequency changes in response to hermeticity status, providing a sensitive measurement method that works effectively for small-volume IMDs regardless of equipment resolution limits.
3Measurement precision
If wire tethering and gas injection methods are used for hermeticity testing, then leak rate can be measured, but the process becomes destructive and requires manual labor
Solution Approach 1:
The patent replaces mechanical wire tethering and gas injection systems with wireless inductive sensing. The LC resonant circuit wirelessly transmits hermeticity data through inductive coupling, eliminating the need for physical connections and manual gas handling operations.
Solution Approach 2:
The IMD automatically monitors its own hermeticity status using the LC resonant circuit and wirelessly transmits the data. This self-diagnosis capability eliminates the need for external measurement equipment and manual testing operations at each checkpoint.
4Measurement precision
If manual data acquisition with bulky VNA is used for wireless hermeticity monitoring, then resonance frequency can be measured, but the process becomes labor-intensive and non-automated
Solution Approach 1:
The IMD contains an integrated LC resonant circuit that automatically monitors its own hermeticity status and wirelessly transmits the resonant frequency data. This eliminates the need for external VNA equipment and manual data acquisition operations.
Solution Approach 2:
The patent extracts the measurement function from external bulky equipment (VNA) and integrates it into the IMD itself through the LC resonant circuit. This miniaturization and integration enable automated wireless monitoring without requiring external measurement equipment.
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 system enables nondestructive, continuous monitoring of hermetic failure in IMDs under accelerated conditions, improving the reliability of hermetic encapsulation and extending the lifetime of IMDs.
Implementation Method 1
monitor the resonance frequency with minimal power reflection to an adjacent readout coil
Implementation Method 2
near-field powering with inductive-capacitive (LC) resonators
Data Source
AI summary
Disclosed is an automated and wireless accelerated heat treat life testing system, and the system includes a readout coil; and an LC sensor on the readout coil, wherein the LC sensor includes: a sensing coil; an IDC sensor on the sensing coil; and a humidity sensing layer on a sensing area of the IDC sensor.