Wafer-patterned, permeable, and stretchable liquid metal microelectrodes for implantable bioelectronics with chronic...

Area of Science:

• Biomedical Engineering
• Materials Science
• Neuroscience

Background:

• Implantable bioelectronics enable real-time physiological monitoring but face challenges with substrate permeability and biocompatibility.
• Existing thin-film substrates (e.g., polyimide, polydimethylsiloxane) offer flexibility but have low permeability, hindering long-term use.
• Porous substrates offer high permeability but lack the high patterning density required for advanced applications.

Purpose of the Study:

• To develop a wafer-scale, patternable strategy for fabricating high-resolution, supersoft, stretchable, and permeable liquid metal microelectrodes (μLMEs).
• To achieve ultrahigh electrode density for advanced neural interface applications.
• To evaluate the chronic biocompatibility and performance of μLMEs as neural interfaces.

Main Methods:

• Photolithography was employed for high-resolution fabrication of μLME arrays on a wafer-size elastic fiber mat.
• Demonstrated 2-μm patterning capability, achieving an electrode density of ~75,500 electrodes/cm².
• Implanted μLME arrays in living rats for electrocorticography (ECoG) signal monitoring.

Main Results:

• Achieved wafer-scale fabrication of supersoft, stretchable, and permeable μLMEs with 2-μm resolution.
• Demonstrated an ultrahigh electrode density of ~75,500 electrodes/cm².
• Successfully used μLME arrays for high spatiotemporal mapping and intervention of ECoG signals in rats, with chronic biocompatibility observed over eight months.

Conclusions:

• The developed photolithography strategy enables the high-resolution fabrication of μLMEs on elastic fiber mats, overcoming limitations of existing bioelectronic substrates.
• The supersoft, stretchable, and permeable μLMEs demonstrate significant potential as advanced neural interfaces for long-term physiological monitoring.
• Chronic implantation of μLMEs showed excellent biocompatibility, paving the way for next-generation implantable bioelectronic devices.