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Accelerated life-test methods and results for implantable electronic devices with adhesive encapsulation
Xuechen Huang1,2, Petcharat May Denprasert3, Li Zhou4
1Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA. xuechenh@usc.edu.
Biomedical Microdevices
|May 25, 2017
Summary
We developed a wireless method to predict the lifespan of implantable electronic devices. This technique detects moisture-induced failures in epoxy-encapsulated devices, ensuring over 99.97% reliability for 1 year.
Area of Science:
- Biomedical Engineering
- Materials Science
- Electrical Engineering
Background:
- Miniature implantable wireless electronic devices require robust encapsulation for long-term function.
- Non-hermetic encapsulants like epoxy are susceptible to moisture ingress, leading to device failure.
- Reliable methods for predicting the functional life of such devices are crucial for medical applications.
Purpose of the Study:
- To develop and validate a wireless sensing method for estimating the functional life of miniature implantable electronic devices.
- To assess the impact of moisture on non-hermetic adhesive encapsulants.
- To establish a predictive model for packaging reliability.
Main Methods:
- Utilized a comb pattern with interdigitated electrodes (IDE) to detect water vapor condensation.
- Employed inductive coupling of an RF magnetic field for wireless DC bias and failure detection.
- Monitored changes in resonant frequency and Q-factor of the device's circuitry due to moisture.
- Correlated wireless signals with visual inspection of introduced defects.
- Validated encapsulation procedures through accelerated life tests.
Main Results:
- Demonstrated sensitivity of the IDE comb pattern to moisture-induced failures.
- Established a wireless detection method for incipient device deterioration.
- Achieved a predicted 1-year packaging reliability of 99.97% for a neuromuscular stimulator.
- Identified strong adhesive bonding as critical for long-term reliability.
Conclusions:
- The developed wireless sensing method accurately estimates the functional life of implantable devices with non-hermetic encapsulants.
- Optimized encapsulation procedures and strong adhesive bonding are essential for achieving high packaging reliability.
- This approach provides a reliable, non-invasive method for quality control and lifecycle prediction in implantable electronics.
