EPSCoR Research Fellows: NSF: Investigating Spatial Photonic Sintering of Metallic Nanoparticles Toward Intense Pulsed Light Assisted Electrohydrodynamic 3D Printing

Direct printing has evolved as an alternative to traditional photolithography and etching based technologies in rapid prototyping and the fabrication of customized electronics, due to its simple, cheap, and clean process. Over the past decades, the evolution of microelectronics has arisen the need for more complex three-dimensional (3D) electronics, such as stacked transistors and 3D integrated circuits.

Nevertheless, most existing 3D printing technologies encounter difficulties when it comes to fabricating microscale 3D electronics. They either have limited printing resolution or cannot maintain the as-printed 3D structures without support. This project aims to develop an innovative photonic sintering assisted 3D printing technology to realize the direct printing of microscale 3D electronics, which has tremendous applications in various areas such as metamaterials, microelectromechanical systems, and biomedical devices.

In addition, this project will expand the advanced manufacturing research capacity at Montana State University (MSU) and contribute to its engineering education by involving several students in interdisciplinary research work. The PI will also invite K-12 students to visit his lab and get hands-on 3D printing experience through several well-established outreach programs at MSU, thus promoting science and engineering awareness among Montanans, especially underrepresented minorities and Native Americans.

Electrohydrodynamic (EHD) printing has emerged as a promising technology to fabricate microscale biological and electronic devices, due to its modest instrumentation requirements, high resolution, and compatibility with a broad range of functional materials. However, EHD printing is currently limited to 2D patterning since the as-printed 3D structures cannot retain their geometrical shapes in midair.

To achieve EHD 3D printing of microelectronics, functional inks must be developed and fine-tuned for desired rheological properties. The conventional trial-and-error approach is both time and resource consuming. To accelerate the ink development process, machine learning will be used in this project to study the relationship between ink composition and rheological properties.

Another challenge is the lack of an efficient on-demand solidifying and sintering mechanism. Photonic sintering seems promising, but it has only been used to sinter thin-film patterns and existing studies are based on 2D models. There exists a knowledge gap in the understanding of photonic sintering process of metallic nanoparticles in 3D patterns.

The main objective of this project is to establish an innovative EHD 3D printing technology, named intense pulsed light assisted EHD 3D printing (IE 3D printing), in which an intense pulsed light is utilized to solidify and sinter the printed patterns dynamically. This project will focus on investigating the ink composition-rheological properties relationship and understanding the photonic sintering process of metallic nanoparticles in 3D micropatterns.

The specific research objectives are: 1) Study the relationship between ink composition and rheological properties; 2) Investigate spatial photonic sintering of metallic nanoparticles; and 3) Establish IE 3D printing to fabricate 3D integrated microelectronics.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.