Researchers from Hong Kong University of Science and Technology (HKUST) have demonstrated the production of piezoelectric elements using electrostatic disc microprinting. Such elements can be used for sensing, actuations, catalysis, and energy harvesting.
This method, detailed in a recent study in Nature Communications, overcomes the limitations of existing techniques that struggle with high productivity and precise control over the structure and feature sizes of nanoparticles, films, and patterns on various substrates.
The core of this technology lies in leveraging the instability of the liquid-air interface in inks, a concept first observed in 1917. It was noted at the time that a strong electrostatic field could destabilize a microfluidic interface, forming a Taylor cone, a conical shape when the fluid is charged beyond the Rayleigh limit. This electrostatically driven cone-jetting phenomenon, found in nature and various applications, has inspired numerous printing strategies, including electrospraying, electrospinning, and droplet focus printing, compatible with MEMS and complementary metal oxide semiconductor fabrication techniques.
Electrostatic disc microprinting has shown remarkable capabilities in fabricating lead zirconate titanate free-standing nanoparticles, films, and micro-patterns. The lead zirconate titanate films produced exhibit a high piezoelectric strain constant of 560 pm V^−1, substantially exceeding existing standards. This new method can achieve depositing speeds up to 10^9 cubic micrometers per second, a speed an order of magnitude faster than current techniques. Moreover, it demonstrates versatility in printing a range of materials, from dielectric ceramic and metal nanoparticles to insulating polymers and biological molecules, making it a promising tool for applications in electronics and biotechnology. The method is not limited to 2 dimensions, and it can print on 3D contoured surfaces, with the feature height being dependent on the number of deposited layers.
The introduction of electrostatic disc microprinting addresses the longstanding challenges in the piezoelectric material fabrication sector, particularly in terms of versatility, volume production, processing temperature, structural compactness, and cost-effectiveness. Traditional methods like screen printing and photolithography/chemical etching, which often require high sintering temperatures and complex processing conditions, fall short in compatibility with flexible substrates and control over feature sizes.
“Our micro printer shows printing capability for wide-ranging classes of materials such as dielectric ceramic, metal nanoparticles, insulating polymers, and biological molecules,” said Professor Prof. Yang Zhengbao, Associate Professor at the Department of Mechanical & Aerospace Engineering at HKUST.
“It boasts the fastest speed in existing techniques for piezoelectric micrometer-thick films, and the PZT films we produced demonstrate excellent piezoelectric properties compared to current ones in the market. This new, affordable model of precision printing with features measurable at ~20 μm is surely going to bring benefits to many in the scientific world, and would lead to many breakthroughs that were previously thought impossible.”
3D printing with piezoelectric materials looks promising, with electrostatic disc microprinting poised to play a pivotal role. Its speed, versatility, and efficiency open new avenues for innovation, particularly in MEMS, wearable electronics, and the Internet of Things. The industry can expect further advancements in printing technologies for complex materials, enhancing the efficiency and versatility of manufacturing processes in electronics and related fields.
The full research paper, titled “Fast and versatile electrostatic disc microprinting for piezoelectric elements” can be found in the Nature Communications journal, at this link.
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