3D Printed Flexible Piezoelectric Sensors for Integrated Hybrid Electronics

The ability to 3D print high performance smart materials and multifunctional devices, all seamlessly integrated via a common manufacturing platform, can yield advances in soft robotics, wearable electronics, and human-machine interfaces. One of the most important smart materials in this context is piezoelectrics, due to their dual capabilities in sensing and actuating, which are critical for creating intelligent, responsive systems. In this study, we develop a direct-ink-writing (DIW) 3D printing approach for creating flexible and wearable piezoelectric devices using solution-processed poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) as the functional ink. Ferroelectric and actuation-based characterizations are conducted to guide systematic optimization of the electrical poling conditions, yielding high performance 3D printed PVDF-TrFE transducers with d₃₁ coefficient of 12.70 ± 0.71 pC·N^-1. Three proof-of-concept smart devices were then fabricated: (1) a touch-based wearable human-machine interface for interactive gaming, (2) a tactile-sensing "electronic skin," and (3) a multifunctional hybrid electronic system combining piezoelectric sensors and quantum dot light-emitting diodes, all fully 3D printed. This work comprehensively demonstrates the ability for 3D printing to generate high performance materials and devices, the use of 3D printing for wearable piezoelectric sensor fabrication, and the versatility of 3D printing for the seamless multifunctional integration of hybrid electronic systems.