Session: 03-03-05: Annual Congress-Wide Symposium on Additive Manufacturing V

Paper Number: 165004

A Computational Analysis of Virtual Impactor Dynamics in Aerosol Jet Printing Toward Optimal Direct-Write Fabrication of Printed Electronics 

Aerosol jet printing (AJP) is a direct-write additive manufacturing technique employed for the fabrication of high-resolution electronic devices, including sensors, capacitors, and optoelectronic components. Its growing prominence stems from its unique ability to leverage aerodynamic principles to precisely deposit conductive inks, such as silver nanoparticle-based inks, onto both rigid and flexible substrates. The AJP system is composed of three critical components that work in unison to execute the printing process: (i) the pneumatic/ultrasonic atomizer, (ii) the virtual impactor (VI), and (iii) the deposition head. Positioned between the atomizer and the deposition head, the virtual impactor plays a pivotal role in the process by accepting the accelerated flow of aerosol particles of varying sizes from the atomizer while serving as an aerodynamic separator. This separation is crucial for ensuring that only the most suitable particles proceed toward deposition, directly impacting the quality and resolution of the printed features. Despite its advantages, AJP faces notable challenges concerning process efficiency, repeatability, and print quality. The virtual impactor, as a central component, offers a unique opportunity to deepen the understanding of aerosol particle flow dynamics and how these behaviors influence the overall performance of AJP. Addressing these intricacies is essential for overcoming inefficiencies and ensuring consistent, high-quality outputs.
This research tackles these challenges by conducting a computational fluid dynamics (CFD)-based investigation of the virtual impactor’s dynamics, aiming to visualize and analyze fluid transport and particle deposition under controlled conditions. The objective of this study is to observe and characterize the compressible and turbulent flow through the virtual impactor within the AJP process. The virtual impactor geometry was modeled using the ANSYS-Fluent environment, adhering to the design specifications provided by Optomec. The assembly comprises key elements such as the housing, collector, jet, stem, O-rings, and a retaining nut. To facilitate accurate simulations, a robust mesh structure was generated to discretize the flow domain. Furthermore, material properties, boundary conditions, and the relevant governing equations, rooted in the Navier-Stokes equations, were incorporated to achieve an accurate, steady-state solution.
Next, the influence of several design parameters, including (i) impactor-collector diameter ratio, (ii) number of pores, (iii) pore diameter, (iv) impactor length, and (v) collector length, was investigated on virtual impactor fluid dynamics, focusing on flow velocity, pressure, turbulent eddy dissipation, and turbulent kinetic energy. The results of this study revealed the presence of non-uniform aerosol flow removal as well as flow circulation within the virtual impactor. Particularly, it was observed that a 0.5 diameter ratio caused backflow, while equal diameters ensured even fluid distribution and increased exhaust chamber velocity. Increasing the number of pores affected flow circulation and velocity, with 16 pores showing the most concentrated flow. Varying pore diameters and impactor lengths also influenced flow behavior and velocity. Pressure contours and turbulence eddy dissipation analyses revealed that a 0.5 diameter ratio could result in the lowest system pressure and highest turbulence. Increasing pore numbers and diameters had a minimal impact on flow pressure and turbulence. Shorter impactor lengths led to more observable eddy dissipation, while longer collector lengths increased overall turbulence. The study also concluded that a 0.5 diameter ratio and increased impactor and collector lengths significantly affected turbulence kinetic energy and eddy dissipation, while the number and diameter of pores had minimal impact. Overall, this research work establishes a foundation for advancing the understanding and performance of aerosol jet printing’s virtual impactor, driving progress toward the precise and efficient fabrication of high-resolution printed electronic devices.

Presenting Author: Roozbeh (Ross) Salary Marshall University (West Virginia State)

Presenting Author Biography: Dr. Salary is an Associate Professor of Mechanical and Biomedical Engineering in the College of Engineering and Computer Sciences at Marshall University. His current areas of research include Advanced Manufacturing, Physics-Based Computational Modeling, Tissue Engineering, Machine Learning (ML) and Artificial Intelligence (AI). Currently, Dr. Salary is serving as the director of the Lab for Advanced Manufacturing Engineering & Systems (LAMES) at Marshall University. Dr. Salary is a recipient of the College of Engineering Research Award as well as Pickens-Queen Teaching Award for excellence in both research and education at Marshall University.

Authors:

Akashita Sareen Marshall University
Curtis Hill NASA MSFC ESSCA
Roozbeh (Ross) Salary Marshall University (West Virginia State)