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Intimate encapsulation of non-planar electrodes via a viscoplastic interlayer
Liqian Liu1, Xinyue Xiang1, Yinglin Zhi1
1Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
National Science Review
|July 3, 2026
Summary
A novel viscoplastic interlayer ensures hermetic encapsulation for implantable electronics with non-planar electrodes. This breakthrough improves device longevity and signal stability in challenging environments.
Area of Science:
- Materials Science
- Biomedical Engineering
- Polymer Science
Background:
- Implantable electronics require non-planar electrodes for conductivity and deformability.
- Conventional elastic seals fail with non-planar electrodes, causing voids and fluid ingress.
- Hermetic encapsulation is crucial for long-term stability of implantable devices.
Purpose of the Study:
- To develop a viscoplastic interlayer for hermetic encapsulation of non-planar electrodes.
- To address the challenge of interfacial voids and fluid ingress in implantable electronics.
- To enhance the long-term stability and signal fidelity of bioelectronic devices.
Main Methods:
- Fabrication of a polymeric composite interlayer using polyisobutylene and maleic anhydride-grafted polypropylene.
- Characterization of the interlayer's viscoplastic properties, including chain slippage and disentanglement.
- Integration of the interlayer with various non-planar electrodes (microwires, micropillars, serpentine) and sealing elastomers.
- Evaluation of encapsulation effectiveness through fluid ingress tests and stability assessments in acidic, neutral, and alkaline solutions.
- Assessment of in vivo signal fidelity duration for stretchable bioelectronics.
Main Results:
- The viscoplastic interlayer successfully adapted to 3D non-planar electrode structures, achieving intimate contact.
- Defect-free interfaces were formed between the interlayer, elastomer, and electrodes via covalent bonding.
- The encapsulated devices maintained a stable signal-to-noise ratio for 50 weeks in various solutions.
- In vivo signal fidelity was extended to a record 45 weeks for stretchable bioelectronics.
Conclusions:
- The developed viscoplastic interlayer provides effective hermetic encapsulation for non-planar electrodes.
- This innovation significantly improves the long-term operational stability of implantable bioelectronic devices.
- The interlayer offers a promising solution for enhancing the reliability and duration of bioelectronic implants.
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