Tissue-Adhesive and Stiffness-Adaptive Neural Electrodes Fabricated Through Laser-Based Direct Patterning

Area of Science:

• Biomedical Engineering
• Materials Science
• Neuroscience

Background:

• Implantable neuroprosthetics for peripheral nerve disorders show promise but face challenges due to mechanical mismatch with nerves, causing tissue damage and performance issues.
• Existing stretchable electrodes often involve complex fabrication and exhibit unstable performance, hindering clinical translation.
• Developing robust and adaptable neural interfaces is crucial for effective diagnostics and electrical stimulation of peripheral nerves.

Purpose of the Study:

• To present an efficient method for creating a tissue-adhesive, stiffness-adaptive peripheral neural interface (TA-SA-PNI).
• To utilize mechanically and electrically stable ultrathin conductive micro/nanomembrane bilayer (UC-MNB) electrodes for improved neural interfacing.
• To demonstrate the efficacy of the TA-SA-PNI in vivo for bidirectional neural applications.

Main Methods:

• Fabrication of UC-MNB electrodes (conductive Cu micromembrane encapsulated by Au nanomembrane) on a tough self-healing polymer (T-SHP) substrate using direct laser patterning.
• Incorporation of a wavy structure in UC-MNB to achieve strain-insensitive electrical performance.
• Integration of a phenylboronic acid-conjugated alginate (Alg-BA) adhesive layer for tissue adhesion and ionic conductivity.
• Evaluation of stiffness adaptation through dynamic stress-relaxation properties of the interface.

Main Results:

• The developed UC-MNB electrodes demonstrated strain-insensitive performance up to 60% strain due to their wavy structure.
• The interface exhibited dynamic stress-relaxation properties, enabling stiffness adaptation to minimize nerve compression.
• The Alg-BA adhesive layer provided stable tissue adhesion and ionic conductivity.
• Successful in vivo demonstrations in rats showed stable bidirectional neural pathway measurements and electrical stimulation of sciatic nerves.

Conclusions:

• The developed TA-SA-PNI, utilizing UC-MNB electrodes and an Alg-BA adhesive layer, offers a promising solution for peripheral neural interfacing.
• The interface's mechanical adaptability and stable electrical performance address key limitations of current neuroprosthetics.
• This technology facilitates seamless integration for advanced neural diagnostics and therapeutic electrical stimulation.