An official website of the United States government
Aerosol jet printing is a compelling technology for hybrid electronics, combining digital and noncontact patterning with broad materials compatibility, resolution as fine as ≈10 microns, and a high standoff distance of 1–5 mm. Despite its growing popularity in research environments, a robust process understanding and improved manufacturing control are essential for achieving the reliability and predictability required for broader adoption in advanced applications. Herein, recent developments in process monitoring using in‐line light scattering measurements are discussed, including their mechanistic foundations, experimental validation, relevance for process control and reliability, and value as a diagnostic tool for fundamental studies. Experimental measurements confirm the correlation between measured light scattering and deposition rate. Building on this platform, feedback from the real‐time measurement is coupled with printer software to support automated closed‐loop control via a simple proportional‐integral‐derivative software control loop. Combined with the utility of these measurements as a diagnostic to accelerate ink formulation and support fundamental process science experiments, this in‐line measurement provides a useful tool to improve print reliability with the potential to advance the adoption and capabilities of this method in conformal, flexible, and hybrid electronics applications.
more »
« less
Real‐Time Optical Process Monitoring for Structure and Property Control of Aerosol Jet Printed Functional Materials
Abstract Aerosol jet printing is a popular digital additive manufacturing method for flexible and hybrid electronics, but it lacks sophisticated real‐time process control schemes that would enable more widespread adoption in manufacturing environments. Here, an optical measurement system is introduced to track the aerosol density upstream of the printhead. The measured optical extinction, combined with the aerosol flow rate, is directly related to deposition rate and accurately predicts functional materials properties such as the electrical resistance of printed graphene films. This real‐time system offers a compelling solution for process drift and batch‐to‐batch variability, rendering it a valuable tool for both real‐time control of aerosol jet printing and fundamental studies of the underlying process science.
more »
« less
- PAR ID:
- 10382050
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 5
- Issue:
- 12
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Aerosol jet printing (AJP) is a direct-write additive manufacturing technique used to fabricate electronics, such as sensors, capacitors, and optoelectronic devices. It has gained significant attention in being able to utilize aerodynamic principles to deposit conductive inks (such as silver nanoparticle-based inks) onto rigid and flexible substrates. The aerosol jet printing system consists of three main components to execute the printing process: (i) the pneumatic atomizer, (ii) the virtual impactor, and (iii) the deposition head. The virtual impactor (VI) lies between the pneumatic atomizer and the deposition head, accepting the accelerated flow of differently sized aerosol particles from the pneumatic atomizer, while acting as an “aerodynamic separator.” With the challenges associated with the efficiency as well as resulting quality of the AJP process, the virtual impactor presents a unique opportunity to gain a deeper understanding of the component itself, aerosol particle flow behavior, and how it contributes to overall printing inefficiencies, poor repeatability, and resulting print quality. Broadly, this effort enables the expedited adoption of AJP in the electronics industry and beyond at large scales. The challenges mentioned are addressed in this work by conducting a computational fluid dynamics (CFD) study of the virtual impactor to visualize fluid transportation and deposition under specific conditions. The objective of this study is to observe and characterize a single-phase, compressible, turbulent flow through the virtual impactor in AJP. The virtual impactor geometry is modeled in the ANSYS-Fluent environment based on the design by Optomec. The virtual impactor is assembled using a housing, collector, jet, stem, O-rings and a retaining nut. Subsequently, a mesh structure is generated to discretize the flow domain. In addition, material properties, boundary conditions, and the relevant governing equations (based on the Navier-Stokes equations) are utilized to, ultimately, generate an accurate steady-state solution. The fluid flow is examined with respect to mass flow rates set at boundary conditions. The aerosol particles’ interactions with the inner walls of the virtual impactor are observed. Particularly, an insight into the characteristics of aerosol particles entering the virtual impactor and their transition into a smoother flow before entering the deposition head is gained. Furthermore, the analysis provides an opportunity to observe fluid flow separation based on the design of the virtual impactor, one of its main functions in the AJP process. This exposes probable causes for inaccurate print quality, flow blockages, inconsistent outputs, process instability, and other material transport inefficiencies. Overall, this research work lays the foundation for improvements in the knowledge and performance of aerosol jet printing’s virtual impactor toward optimal fabrication of printed electronics.more » « less
-
Dimov, Stefan; Zhang, TieJun (Ed.)Abstract Aerosol jet printing (AJP) is a direct-write additive manufacturing technique used to fabricate electronics, such as sensors, capacitors, and optoelectronic devices. It has gained significant attention in being able to utilize aerodynamic principles to deposit conductive inks (such as silver nanoparticle-based inks) onto rigid and flexible substrates. The aerosol jet printing system consists of three main components to execute the printing process: (i) the pneumatic atomizer, (ii) the virtual impactor, and (iii) the deposition head. The virtual impactor (VI) lies between the pneumatic atomizer and the deposition head, accepting the accelerated flow of differently sized aerosol particles from the pneumatic atomizer while acting as an “aerodynamic separator.” With the challenges associated with efficiency as well as resulting quality of the AJP process, the virtual impactor presents a unique opportunity to gain a deeper understanding of the component itself, aerosol particle flow behavior, and how it contributes to overall printing inefficiencies, poor repeatability, and resulting print quality. Broadly, this effort enables the expedited adoption of AJP in the electronics industry and beyond large scales. The challenges mentioned are addressed in this work by conducting a computational fluid dynamics (CFD) study of the virtual impactor to visualize fluid transportation and deposition under specific conditions. The objective of this study is to observe and characterize a single-phase, compressible, turbulent flow through the virtual impactor in AJP. The virtual impactor geometry is modeled in the ANSYS FLUENT environment based on the design by Optomec. The virtual impactor is assembled using a housing, collector, jet, stem, O-rings, and a retaining nut. Subsequently, a mesh structure is generated to discretize the flow domain. In addition, material properties, boundary conditions, and the relevant governing equations (based on the Navier–Stokes equations) are utilized to, ultimately, generate an accurate steady-state solution. The fluid flow is examined with respect to mass flow rates set at boundary conditions. The aerosol particles' interactions with the inner walls of the virtual impactor are observed. Particularly, an insight into the characteristics of aerosol particles entering the virtual impactor and their transition into a smoother flow before entering the deposition head is gained. Furthermore, the analysis provides an opportunity to observe fluid flow separation based on the design of the virtual impactor, one of its main functions in the AJP process. This exposes probable causes for inaccurate print quality, flow blockages, inconsistent outputs, process instability, and other material transport inefficiencies. Overall, this research work lays the foundation for improvements in the knowledge and performance of aerosol jet printing's virtual impactor toward optimal fabrication of printed electronics.more » « less
-
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.more » « less
-
Abstract Human induced pluripotent stem cells (iPSCs) hold great promise for reducing the mortality of cardiovascular disease by cellular replacement of infarcted cardiomyocytes (CMs). CM differentiation via iPSCs is a lengthy multiweek process and is highly subject to batch‐to‐batch variability, presenting challenges in current cell manufacturing contexts. Real‐time, label‐free control quality attributes (CQAs) are required to ensure efficient iPSC‐derived CM manufacturing. In this work, we report that live oxygen consumption rate measurements are highly predictive CQAs of CM differentiation outcome as early as the first 72 h of the differentiation protocol with an accuracy of 93%. Oxygen probes are already incorporated in commercial bioreactors, thus methods presented in this work are easily translatable to the manufacturing setting. Detecting deviations in the CM differentiation trajectory early in the protocol will save time and money for both manufacturers and patients, bringing iPSC‐derived CM one step closer to clinical use.more » « less
