Fractal-Based Stretchable Circuits via Electric-Field-Driven Microscale 3D Printing for Localized Heating of Shape...

Area of Science:

• Materials Science
• Additive Manufacturing
• Polymer Science

Background:

• Traditional 4D printing of shape memory polymers (SMPs) faces limitations with external heating or rigid embedded heaters.
• Current methods lack precise thermal control and struggle with the stretching required for shape programming.

Purpose of the Study:

• To develop a novel 4D printing paradigm using stretchable fractal heating circuits integrated with SMPs.
• To overcome the limitations of existing heating strategies in 4D printing applications.

Main Methods:

• Fabrication of stretchable heating circuits with fractal motifs using electric-field-driven microscale 3D printing of conductive paste.
• Integration of these circuits into 3D printed structures containing SMP components.
• Tuning of fractal order and printing parameters to control electrical resistance and heating uniformity.
• Evaluation of circuit performance under uniaxial and biaxial stretching compared to serpentine structures.

Main Results:

• Fractal-based heating circuits demonstrate stable electrical resistance under stretching, unlike serpentine structures.
• The circuits provide efficient and uniform heating, tunable via fractal order and printing parameters.
• Demonstrated successful shape programming and actuation of 4D printed structures using both uniaxial and biaxial stretching.
• Enabled shape transformation from planar to double-curved 3D structures due to biaxial stretchability.

Conclusions:

• The proposed fractal heating circuit strategy offers enhanced control and design freedom for 4D printed SMP structures.
• This approach facilitates seamless integration and manipulation of complex 3D printed objects.
• Paves the way for more sophisticated and practical applications of 4D printing technology.