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Aerosol jet printing (AJP) is a direct-write additive manufacturing technique used for producing high-resolution electronic components such as sensors, capacitors, and optoelectronic devices. The increasing adoption of AJP is attributed to its ability to precisely deposit conductive inks, such as silver nanoparticle-based inks, onto both rigid and flexible substrates. The AJP system comprises three core components: (i) the atomizer, (ii) the virtual impactor (VI), and (iii) the deposition head. The VI, situated between the atomizer and the deposition head, plays a critical role by separating aerosol particles based on their size. This aerodynamic separation ensures that only appropriately sized particles continue to the deposition head, directly influencing print resolution and quality. Despite the advantages of AJP, challenges remain related to process efficiency, repeatability, and print fidelity influenced by the VI. This research work contributes to addressing these issues by establishing a computational fluid dynamics (CFD) model to analyze the internal flow dynamics of the VI. The geometry of the VI, modeled in ANSYS Fluent using design data provided by Optomec (a manufacturer of AJP systems), includes the housing, stem, impactor, collector, and exhaust outlet. In this study, a zone-adapted mesh structure was generated to discretize the internal flow domain. The boundary conditions of the CFD model were set based on experimental observations. Pressure-based CFD formulation using Navier-Stokes equations was utilized to simulate incompressible, turbulent flows under steady-state conditions. The aim of this study is to investigate the effects of several design parameters on VI performance, including: (i) impactor-to-collector diameter ratio (IDtCDR), (ii) number of aerodynamic transport channels (pores), (iii) pore diameter, (iv) impactor length, and (v) collector length. The results of this study revealed that flow behavior in the virtual impactor (VI) is highly sensitive to geometric parameters, particularly the impactor-to-collector diameter ratio (IDtCDR), impactor length (IL), and collector length (CL). An IDtCDR of 0.5 results in backflow, low pressure, and a very high level of turbulence near the collector nozzle, while IDtCDR=1.0 (i.e., when the impactor and collector have equal diameters) provides uniform flow and optimal exhaust velocity. Increasing impactor length as well as collector length raises overall turbulence and pressure. In contrast, variations in the number and diameter of aerodynamic transport channels (ATC) have minimal influence on turbulence or pressure. Overall, this study provides new insights into the influence of geometric design on flow characteristics within the VI and establishes a foundation for optimizing AJP systems. By understanding how design parameters affect flow velocity, pressure distribution, and turbulence behavior, this work supports the advancement of consistent, high-performance AJP processes for the precise fabrication of next-generation electronic devices.
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This content will become publicly available on May 2, 2026
A Computational Fluid Dynamics Approach to Analyze the Virtual Impactor in Pneumatic Aerosol Jet Printing
Aerosol jet printing (AJP) is a 3D printing, advanced manufacturing process that generates an aerosol mist appropriate for fine printing small, low-volume electronic parts. The pneumatic aerosol jet printing technology’s virtual impactor is the focus of this study. In this technology, high velocity nitrogen gas aerosolizes various inks in the atomizer. The aerosolized stream of ink is then transported to a virtual impactor (VI) to become dense and concentrated as it begins to enter the deposition head for high precision electronics printing. AJP faces challenges in large-scale adoption due to challenges related to overspray, instability, ink clogging etc. There is discrepancy in the knowledge of the sources that cause such issues. Computationally simulating the pneumatic aerosol jet printing environment provides insights into unapparent ink flow behavior that may contribute to printing inefficiencies in the system. While the pneumatic atomizer and deposition head are sufficiently simulated and analyzed, the VI lacks the same focus. Therefore, simulating the VI environment provides a comprehensive understanding of the pneumatic AJP technology. This is accomplished by 3D computational fluid dynamics (CFD) modeling and simulation of the VI system in ANSYS Fluent. First, an initial characterization of the system is completed by creating a 3D CAD model based on x-ray images of the VI by Optomec and a subsequent CFD analysis using a turbulent k-epsilon model. Second, design investigations and corresponding CFD simulations are conducted by altering critical design parameters in the system such as the impactor and collector lengths, impactor to collector diameter ratio, and aerodynamic transport channels (ATC) count and diameter. The initial characterization study revealed that the VI experiences non-uniform flow removal, flow circulation, and increased EGF port velocity.
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- Award ID(s):
- 2327460
- PAR ID:
- 10637249
- Publisher / Repository:
- Marshall Digital Scholar (https://mds.marshall.edu/etd/1940)
- Date Published:
- Format(s):
- Medium: X
- Institution:
- Marshall University
- Sponsoring Org:
- National Science Foundation
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