Aerosol jet printing polymer dispersed liquid crystals on highly curved optical surfaces and edges

Machine learning enables electrical resistivity modeling of printed lines in aerosol jet 3D printing

Among various non-contact direct ink writing techniques, aerosol jet printing (AJP) stands out due to its distinct advantages, including a more adaptable working distance (2-5 mm) and higher resolution (~ 10 μm). These characteristics make AJP a promising technology for the precise customization of intricate electrical functional devices. However, complex interactions among the machine, process, and materials result in low controllability over the electrical performance of printed lines. This significantly affects the functionality of printed components, thereby limiting the broad applications of AJP. Therefore, a systematic machine learning approach that integrates experimental design, geometrical features extraction, and non-parametric modeling is proposed to achieve printing quality optimization and electrical resistivity prediction for the printed lines in AJP. Specifically, three classical convolutional neural networks (CNNs) architectures are compared for extracting representative features of printed lines, and an optimal operating window is identified to effectively discriminate better line morphology from inferior printed line patterns within the design space. Subsequently, three representative non-parametric machine learning techniques are employed for resistivity modeling. Following that, the modeling performances of the adopted machine learning methods were systematically compared based on four conventional evaluation metrics. Together, these aspects contribute to optimizing the printed line morphology, while simultaneously identifying the optimal resistivity model for accurate predictions in AJP.

Revealing The Morphology of Ink and Aerosol Jet Printed Palladium-Silver Alloys Fabricated from Metal Organic Decomposition Inks

Palladium films hold signicance due to their remarkable affinity for hydrogen diffusion, rendering them valauble for the seperation and purification of hydrogen in membrane reactors. However, palladium is expensive, and its films can become brittle after only a few cycles of hydrogen separation. Alloying with silver has been shown to overcome the problem of palladium embrittlement. Palladium-silver films have been produced via several methods but all have drawbacks, such as difficulties controlling the alloy composition. This study explores two promising jet printing methods: Inkjet and Aerosoljet. Both methods offer potential advantages such as direct patterning, which reduces waste, enables thin film production, and allows for the control of alloy composition. For the first time, palladium-silver alloys have been produced via inkjet printing using a palladium-silver metal organic decomposition (MOD) ink, which alloys at a temperature of 300 °C with nitrogen. Similarly, this study also demonstrates a pioneering approach for Aerosol Jet printing, showing the potential of a novel room-temperature method, for the deposition of palladium-silver MOD inks. This low temperature approach is considered an important development as palladium-silver MOD inks are originally designed for deposition on heated substrates.

Experimental and Numerical Investigation on the Aerosol Micro-Jet 3D Printing of Flexible Electronic Devices

In this study, the optimal forming parameters for printing flexible circuits using aerosol jet printing technology are explored through numerical simulation and experiments. The printhead during the deposition process is numerically simulated. By employing the controlled variable method, the process parameters such as gas flow rate, working distance, nozzle diameter, and printing speed are selected to investigate their effects on the morphology of the printed lines. Accordingly, single-factor experiments are designed to validate the printing of flexible circuits on both planar and curved substrates. Laser micro-sintering is utilized to improve the conductivity of the printed lines and ultimately fabricate flexible strain sensors. Under the sheath gas flow rate of 400 sccm, carrier gas flow rate of 100 sccm, working distance of 3 mm, nozzle diameter of 500 μm, and printing speed of 10 mm/s, the optimal morphology of the printed lines is achieved with low linewidth characteristics. The variations in the focal ratio, working distance, nozzle diameter, and printing speed significantly affect the minimum feature line width and morphology of the printed lines.

A hybrid multi-objective optimization of functional ink composition for aerosol jet 3D printing via mixture design and response surface methodology

The limited electrical performance of microelectronic devices caused by low inter-particle connectivity and inferior printing quality is still the greatest hurdle to overcome for Aerosol jet printing (AJP) technology. Despite the incorporation of carbon nanotubes (CNTs) and specified solvents into functional inks can improve inter-particle connectivity and ink printability respectively, it is still challenging to consider multiple conflicting properties in mixture design simultaneously. This research proposes a novel hybrid multi-objective optimization method to determine the optimal functional ink composition to achieve low electrical resistivity and high printed line quality. In the proposed approach, silver ink, CNTs ink and ethanol are blended according to mixture design, and two response surface models (ReSMs) are developed based on the Analysis of Variance. Then a desirability function method is employed to identify a 2D optimal operating material window to balance the conflicting responses. Following that, the conflicting objectives are optimized in a more robust manner in the 3D mixture design space through the integration of a non-dominated sorting genetic algorithm III (NSGA-III) with the developed ReSMs and the corresponding statistical uncertainty. Experiments are conducted to validate the effectiveness of the proposed approach, which extends the methodology of designing materials with multi-component and multi-property in AJP technology.