Direct laser writing of electronically conductive microstructures within soft hydrogel substrates

Area of Science:

• Materials Science
• Bioelectronics
• Biomedical Engineering

Background:

• Hydrogels offer tissue-like properties for bioelectronic interfaces but lack electrical conductivity and mechanical stability.
• Functionalizing hydrogels with conductive particles improves conductivity, but patterning these features remains difficult.
• Developing methods for patterning conductive elements in soft hydrogels is crucial for advanced bioelectronic applications.

Purpose of the Study:

• To create covalently crosslinked hydrogels with tunable mechanical properties (Young's moduli < 30 kPa).
• To functionalize these hydrogels with metallic electronically conductive paths.
• To demonstrate precise patterning of conductive features within hydrogels for bioelectronic integration.

Main Methods:

• Utilized two-photon direct laser writing to pattern conductive structures.
• Tailored hydrogel substrate composition to control writing fidelity and feature size.
• Incorporated metallic conductive paths achieving high electronic conductivity.

Main Results:

• Achieved electronic conductivity up to (1505 ± 518) S cm⁻¹ in functionalized hydrogels.
• Demonstrated high writing fidelity (±5%) with feature widths as narrow as 5 μm.
• Successfully patterned conductive structures on the surface and within the bulk of soft hydrogels.

Conclusions:

• Developed a method for creating soft, conductive, and patternable hydrogels for bioelectronics.
• These patterned hydrogels enable the creation of miniaturized bioelectronic interfaces.
• Potential applications include advanced cellular and tissue electrophysiology studies and devices.