4D-printed multifunctional hydrogels as flexible strain sensors and nerve conduits

Area of Science:

• Biomaterials Engineering
• Tissue Engineering
• Bioelectronics

Background:

• Conductive hydrogels are essential for bioelectronics and repairing electroactive tissues.
• Fabricating conductive hydrogels into complex, bioactive shapes remains a significant challenge.

Purpose of the Study:

• To develop multifunctional conductive hydrogels using 4D printing for bioelectronic applications.
• To assess the potential of these hydrogels as strain sensors and for peripheral nerve regeneration.

Main Methods:

• Utilized dual-component alginate hydrogel inks with acid-functionalized carbon nanotube (fCNT) nanofillers.
• Employed 3D and 4D printing techniques to create complex hydrogel structures.
• Evaluated electrical conductivity, mechanical properties, cell proliferation, and in vivo nerve regeneration in a rat model.

Main Results:

• Achieved an electrical conductivity of 6.6 ± 0.5 mS cm⁻¹ at 2 mg ml⁻¹ fCNT loading.
• Successfully applied 3D-printed gels as strain sensors for subtle human motion detection.
• Demonstrated programmable shape changes in 4D-printed bilayered hydrogels for intricate nerve guidance conduit designs.
• Observed enhanced neural cell proliferation and improved peripheral nerve regeneration with fCNT-gels in vivo.
• Established sutureless deployment of fCNT-gels for nerve repair.

Conclusions:

• Fabricated 4D-printed multifunctional conductive hydrogels with excellent electrical and mechanical properties.
• Demonstrated the utility of these hydrogels for advanced bioelectronic devices, including strain sensors and nerve guidance conduits.
• Showcased significant potential for enhanced peripheral nerve regeneration and sutureless nerve repair.