4D printing of trigger-free shape-memory hydrogels towards self-adaptive substrates for bioelectronics

Area of Science:

• Biomaterials Engineering
• Bioelectronics
• 4D Printing

Background:

• Shape-changing smart substrates offer minimally invasive, adaptive solutions for implantable bioelectronics.
• Current limitations include challenges in precise shapeshifting control, trigger accessibility, and customization.

Purpose of the Study:

• To introduce a digital 4D printing technique for fabricating customized shape memory hydrogel substrates.
• To enable trigger-free shapeshifting with predefined onset periods for implantable devices.

Main Methods:

• Utilized digital 4D printing with spatio-temporal light exposure to create pixelated polymer sheets with heterogeneous networks.
• Engineered spatially controlled onset times for shape recovery via variations in polymeric network structure.
• Conducted in-vivo testing on male mice to assess biocompatibility.

Main Results:

• Fabricated intricate 3D shapes with autonomous, multi-stage shape recovery through a single digital exposure process.
• Demonstrated trigger-free, programmable shape recovery with controlled onset times.
• Confirmed negligible inflammation in in-vivo experiments, indicating good biocompatibility.

Conclusions:

• The digital 4D printing technique advances time-dependent adaptability for implantable bioelectronics.
• This method expands the functional scope of bioelectronics by enabling complex, pre-programmed shape transformations.
• The developed hydrogel substrates show promise for next-generation adaptive medical devices.