Near-Field Direct Writing Based on Piezoelectric Micromotion for the Programmable Manufacturing of Serpentine Structures

Serpentine microstructures offer excellent physical properties, making them highly promising in applications in stretchable electronics and tissue engineering. However, existing fabrication methods, such as electrospinning and lithography, face significant challenges in producing microscale serpentine structures that are cost-effective, efficient, and controllable. These methods often struggle with achieving precise control over fiber morphology and scalability. In this study, we developed a near-field direct writing (NFDW) technique incorporating piezoelectric micromotion to enable the precise fabrication of serpentine micro-/nanofibers by incorporating micromotion control with macroscopic movement. Modifying the fiber structure allowed for adjustments to the mechanical properties, including tunable extensibility and distinct characteristics. Through the control of the frequency and amplitude of the piezoelectric signal, the printing errors were reduced to below 9.48% in the cycle length direction and 6.33% in the peak height direction. A predictive model for the geometrical extensibility of serpentine structures was derived from Legendre's incomplete elliptic integral of the second kind and incorporated an error correction factor, which significantly reduced the calculation errors in predicting geometric elongation, by 95.85%. The relationship between microstructure bending and biomimetic non-linear mechanical behavior was explored through tensile testing. By controlling the input electrical signals, highly ordered serpentine microstructures were successfully fabricated, demonstrating potential for use in biomimetic mechanical scaffolds.