Thermal-Sinterable EGaIn Nanoparticle Inks for Highly Deformable Bioelectrode Arrays.

Area of Science:

• Materials Science
• Nanotechnology
• Soft Electronics

Background:

• Liquid metal (eutectic gallium indium, EGaIn) nanoparticle inks offer potential for soft electronics but face challenges with substrate wettability and oxide shell formation.
• Traditional sintering methods for EGaIn nanoparticles (EGaIn NPs) require specific conditions and can lead to issues like leakage and droplet reformation.

Purpose of the Study:

• To develop a novel, thermal-sinterable EGaIn NP ink for creating conductive paths in soft electronics.
• To engineer highly stretchable and stable bioelectrode arrays with improved electromechanical performance and reduced electrochemical impedance.

Main Methods:

• Incorporation of thermal expansion microspheres (TEMs) into EGaIn NP solutions to create thermal-sinterable inks.
• Utilizing the mechanical pressure from expanded TEMs to sinter EGaIn NPs into conductive pathways.
• Hermetically sealing recording sites with ionic elastomer layers to ensure leakage-free properties and reduce impedance.

Main Results:

• Achieved highly stretchable bioelectrode arrays with giant electromechanical performance (up to 680% strain).
• Demonstrated excellent cyclic stability (over 2 × 10^4 cycles) and conductivity retention after high-speed rotation (6000 rpm).
• Reduced electrochemical impedance to 891.16 Ω at 1 kHz and ensured complete leakage-free operation.

Conclusions:

• The novel TEM-based sintering strategy overcomes limitations of traditional methods, promoting EGaIn application in soft electronics.
• The developed bioelectrodes are suitable for monitoring dynamic electromyographic signals, showcasing practical utility.
• This approach enhances conductivity, stretchability, and stability for advanced soft electronic devices.