A novel electrohydrodynamic jet (E-Jet) 3D nanoprinting technique has been applied by a joint team from Ningbo University and the University of Hong Kong to fabricate true nanoscale piezoceramic structures with an ultra-high resolution of ~40 nm and an aspect ratio of ~400, surpassing the limitations of conventional printing methods. The printed PZT nanostructures exhibit excellent crystallinity, large elastic strain (~13%), and high piezoelectric performance (d₃₁ ≈ 236.5 × 10⁻¹² C·N⁻¹).

The work, reported in International Journal of Extreme Manufacturing (IJEM, IF: 21.3), enables the development of ultra-sensitive piezoelectric sensors, including a bioinspired PZT air-flow sensor capable of detecting airflow as low as 0.02 m·s⁻¹. This breakthrough opens new possibilities for next-generation high-performance sensors, actuators, and self-powered electronic devices.

Traditional methods for fabricating piezoelectric nanostructures struggle to achieve true nanoscale resolution, limiting their potential in high-performance sensors and actuators.

"We wanted to break this barrier," said Kai Li, corresponding author and researcher at Ningbo University. "Current 3D printing techniques can't produce PZT structures at the nanoscale without defects. Our goal was to develop a precise and scalable method that enables high-resolution printing while preserving the excellent piezoelectric properties of PZT. With our approach, we can now fabricate ultra-sensitive piezoelectric devices that were previously hard to achieve."

Piezoelectric materials like lead zirconate titanate (PZT) have been widely used in sensors and actuators for decades, but manufacturing them at the nanoscale has remained a major challenge. Traditional fabrication methods, such as thin-film deposition and lithography, often require complex, multi-step processes and struggle to create high-resolution, defect-free structures.

With the growing demand for high-performance, miniaturized electronics—especially in areas like wearable sensors, micro-electromechanical systems (MEMS), and the Internet of Things (IoT)—there is an urgent need for more precise and scalable manufacturing techniques. Existing 3D printing methods can produce microscale PZT structures but fail to achieve true nanoscale precision, limiting their application in next-generation devices.

The research team developed a novel electrohydrodynamic jet (E-Jet) 3D nanoprinting technique to fabricate nanoscale PZT structures with ultra-high resolution. By applying a carefully controlled electric field and thermal energy, they created fine PZT jets that solidify into precise, high-aspect-ratio nanostructures, overcoming the limitations of traditional printing methods. This approach enables the direct printing of complex 3D architectures with minimal defects and excellent piezoelectric properties.

Over several years, the team systematically optimized their printing process, testing different parameters to ensure structural integrity and performance. They analyzed the printed PZT nanostructures using advanced imaging techniques, measured their mechanical properties with nanoindentation, and evaluated their piezoelectric performance under controlled bending and stretching conditions. To demonstrate real-world applications, they printed a bioinspired PZT air-flow sensor and tested its sensitivity in detecting ultra-low airflows, achieving excellent results.

"Our 3D nanoprinting technique opens up exciting possibilities for next-generation piezoelectric devices," said Kai Li, corresponding author of the study. "With the ability to fabricate true nanoscale PZT structures, we can develop ultra-sensitive sensors, self-powered wearable electronics, and advanced medical implants. This breakthrough brings us one step closer to high-performance, miniaturized electronics with unprecedented precision."

The team plans to further refine their printing process to enhance scalability and explore new material combinations for even greater flexibility and performance. "We want to push the limits of what’s possible with 3D nanoprinting," Li added. "Our next steps include integrating these PZT nanostructures into multifunctional smart devices and improving their durability for real-world applications, from biomedical sensors to next-generation robotics."