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1. Characterizing the Conductivity of Aerosol Jet Printed Silver Features on Glass

   https://doi.org/10.1115/MSEC2021-63803  

   Ratnayake, Dilan; Curry, Alexander Thomas; Qu, Chuang; Usher, John; Walsh, Kevin (June 2021, 16th International Manufacturing Science and Engineering Conference)

   Aerosol Jet Printing shows a lot of promise for the future of printable electronics. It is compatible with a wide range of materials and can be printed on nearly any type of surface features because of its 3–5 mm standoff distance from the substrate. However, nearly all materials printed require some form of post-sintering processing to reduce the electrical resistance. Many companies develop these materials, but only provide a narrow range of post processing results to demonstrate the achievable conductivity values. In this paper, a design of experiment (DOE) is presented that demonstrates a way to characterize any material for Aerosol Jet Printing during and after post sintering processing by measuring conductivity with different time and temperature values. From these results, a linear regression model can be made to develop an equation that predicts conductivity at a given time-temperature value. This paper applies this method to Clariant Ag ink and sinters silver pads in an oven. A linear regression model is successfully developed that fits the data very well. From this model, an equation is derived to predict the conductivity of the Clariant Ag ink for any time-temperature value. Although only demonstrated with an oven and one type of ink, this method of experimentation and model development can be done with any material and any post processing method. 

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2. Experimental Assessment and Data-Driven Modeling of Three-Dimensional-Printed Conductive Patterns on Electrospun Substrates

   https://doi.org/10.1115/1.4069361  

   Zuniga, Pablo Andres; Zuniga-Navarrete, Christian; Segura, Stalin Jamil; Guo, Zipeng; Baidya, Sabur; Narvaez-Munoz, Christian; Koehne, Jessica; Segura, Luis Javier (December 2025, Journal of Micro and Nano Science and Engineering)

   Abstract Flexible electronics (FE) have emerged as a key technology with applications in various fields, e.g., energy storage and bio-electronics. Electrospinning (ES), inkjet printing (IJP), and intense pulsed light (IPL), constitute a flexible multistage system capable to handle high customization requirements. The ES/IJP/IPL system is used for flexible substrate fabrication, conductive patterns printing, and sintering, respectively. Although the ES/IJP/IPL system seems to be suitable for on-demand FE devices manufacturing, the correlation of materials and process parameters of individual stages (i.e., ES/IJP/IPL) with the FE devices performance (i.e., conductivity) remains unexplored. Therefore, the objective of this paper is to evaluate the integration of ES, IJP, and IPL, for future production of high-performance FE devices. Various materials and process parameters are used to investigate their influence on the FE device resistivity, including different polyacrylonitrile (PAN) concentrations, voltage regimes, flow rates and the collector types in ES, and distinct number of ink layers in IJP. The study includes (1) an experimental assessment of the electrospun membrane morphology (e.g., fiber diameter) and ink coating characteristics (e.g., ink penetration) using scanning electron microscopy (SEM), and (2) a data-driven analysis through logistic regression (LR), Gaussian process (GP), and Bayesian neural network (BNN) classification models to predict FE conductive feasibility. The results indicate that membranes with larger fiber diameters benefit ink penetration, printed layer/multilayer consistency, and conductivity. This is corroborated with the classification models, where the number of printed layers, fiber diameter, and collector type, are identified as significant factors for accurately predicting conductive patterns feasibility. 

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3. Inkless Multimaterial Printing Flexible Electronics by Directed Laser Deposition at Nano- and Microscale

   https://doi.org/10.1021/acsanm.3c01814  

   Ahmadi, Zabihollah; Patel, Aarsh; Taba, Adib; Jaiswal, Suman; Lee, Seungjong; Shamsaei, Nima; Mahjouri-Samani, Masoud (August 2023, ACS Applied Nano Materials)

   Additively manufactured electronics (AMEs), also known as printed electronics, are becoming increasingly important for the anticipated Internet of Things (IoT). This requires manufacturing technologies that allow the integration of various pure functional materials and devices onto different flexible and rigid surfaces. However, the current ink-based technologies suffer from complex and expensive ink formulation, ink-associated contaminations (additives/solvents), and limited sources of printing materials. Thus, printing contamination-free and multimaterial structures and devices is challenging. Here, a multimaterial additive nanomanufacturing (M-ANM) technique utilizing directed laser deposition at the nano and microscale is demonstrated, allowing the printing of lateral and vertical hybrid structures and devices. This M-ANM technique involves pulsed laser ablation of solid targets placed on a target carousel inside the printer head for in-situ generation of contamination-free nanoparticles, which are then guided via a carrier gas toward the nozzle and onto the surface of the substrate, where they are sintered and printed in real-time by a second laser. The target carousel brings a particular target in engagement with the ablation laser beam in predetermined sequences to print multiple materials, including metals, semiconductors, and insulators, in a single process. Using this M-ANM technique, various multimaterial devices such as silver/zinc oxide (Ag/ZnO) photodetector and hybrid silver/aluminum oxide (Ag/Al2O3) circuits are printed and characterized. The quality and versatility of our M-ANM technique offer a potential manufacturing option for emerging IoT. 

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4. Rapid thermal annealing of CH ₃ NH ₃ PbI ₃ perovskite thin films by intense pulsed light with aid of diiodomethane additive

   https://doi.org/10.1039/c8ta01237g  

   Ankireddy, Krishnamraju; Ghahremani, Amir H.; Martin, Blake; Gupta, Gautam; Druffel, Thad (January 2018, Journal of Materials Chemistry A)

   The organic metal halide perovskite material is capable of high throughput manufacturing via traditional deposition processes used in roll-to-roll, yet thermal annealing post deposition may require long ovens. We report rapid annealed perovskite thin films using intense pulsed light (IPL) to initiate a radiative thermal response that is enabled by an alkyl halide additive that collectively improves the performance of a device processed in an ambient environment from a baseline of 10 to 16.5% efficiency. Previous reports on CH 3 NH 3 PbI 3 perovskite films using IPL processing achieved functional devices in milli-second time scales and are promising for high throughput manufacturing processes under ambient conditions. In this study, we found that the addition of diiodomethane (CH 2 I 2 ) as an additive to the methylammonium iodide (MAI)/lead iodide (PbI 2 ) precursor ink chemistry and subsequent IPL thermal annealing are inter-dependent. The concentration of CH 2 I 2 and IPL processing parameters have a direct effect on the surface morphology of the films and performance within a perovskite solar cell (PSC). The CH 2 I 2 dissociates under exposure to ultraviolet (UV) radiation from the IPL source liberating iodine ions in the film, influencing the perovskite formation and reducing the defect states. We anticipate that these results can be utilized to further develop different ink formulations using alkyl halides for the IPL technique to improve the performance of perovskite solar cells processed in ambient conditions. 

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5. A seed and bridge layer method for inkjet printing of narrow traces on receding ink-substrate combinations

   https://doi.org/10.1088/2058-8585/ad1051  

   Pratt, Nicholas; Rao, Pratap M (December 2023, Flexible and Printed Electronics)

   Abstract Inkjet printing of electronic materials is of interest for digital printing of flexible electronics and sensors, but the width of the inkjet-printed lines is still large, limiting device size and performance. Decreasing the drop volume, increasing the drop spacing, and increasing the ink-substrate contact angle are all approaches by which the line width can be lowered, however these approaches are limited by the nozzle geometry, ink coalescence and bead instabilities, and contact angle hysteresis, respectively. Here we demonstrate a novel approach for stable inkjet printing of very narrow lines on ink-substrate combinations with a high contact angle, utilizing the de-wetting of the ink due to the decreased contact angle hysteresis. After printing and drying an initial layer of disconnected seed drops of silver nanoparticle ink, we print an additional layer of bridging drops of the same ink in between the dried seed drops. The bridging drops expand to touch the dried seed drops and then retract into a line, due to the pinning of the wet ink on the dried seed ink but not on the substrate, forming a continuous silver trace. The trace width is decreased from 60μm with a traditional printing approach down to 12.6μm with this seed-bridge approach. The electrical conductivity of the silver trace is similar to that of a conventionally printed trace. Due to poor adhesion on the print substrate, the trace was transferred to a separate polymer substrate with a simple hot-pressing procedure, which preserves the electrical conductivity of the trace. 

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