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1. A Dynamic System Model for Roll-to-Roll Dry Transfer of Two-Dimensional Materials and Printed Electronics

   https://doi.org/10.1115/1.4054187  

   Zhao, Qishen; Hong, Nan; Chen, Dongmei; Li, Wei (July 2022, Journal of Dynamic Systems, Measurement, and Control)

   Abstract Roll-to-roll (R2R) dry transfer is an important process for manufacturing of large-scale two-dimensional (2D) materials and printed flexible electronics. Existing research has demonstrated the feasibility of dry transfer of 2D materials in a roll-to-roll setting with mechanical peeling. However, the process presents a significant challenge to system control due to the lack of understanding of the mechanical peeling behavior and the complexity of the nonlinear system dynamics. In this study, an R2R peeling process model is developed to understand the dynamic interaction among the peeling process parameters, including adhesion energy, peeling force, angle, and speed. Both simulation and experimental studies are conducted to validate the model. It is shown that the dynamic system model can capture the transient behavior of the R2R mechanical peeling process and be used for the process analysis and control design. 

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2. Tension Control in Roll-to-Roll Mechanical Peeling for 2D Material Transfer and Transfer Printing

   Zhao, Q. (December 2021, 2021 International Conference on Micro- and Nano-devices Enabled by R2R Manufacturing)

   Sreenivasan, S.V. (Ed.)

   A major challenge of the large-scale application of two-dimensional (2D) materials is the scaling up of the process for its growth and transfer. Mechanical peeling has been demonstrated to be a promising method for transferring graphene in a fast and environmentally friendly manner. However, efforts in scaling up the process have been lacking. Performing mechanical peeling using a roll-to-roll (R2R) system could significantly increase the throughput of graphene transfer. Such a R2R process does not exist in industry. In this paper a novel R2R mechanical peeling system that has both speed and tension control capabilities is presented. Controllers that control the peeling tensions on both sides of the peeling front are developed based on a tension dynamics model. Both controllers contain a feedback and a feedforward term to account for large steady-state error. The control performance is validated using both experiments and simulation, demonstrating that the R2R mechanical peeling technique can be a viable method for dry transfer of 2D materials in a high-throughput industrial setting. 

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3. MODEL BASED REPETITIVE CONTROL FOR PEELING FRONT GEOMETRY CONTROL IN A ROLL-TO-ROLL PEELING PROCESS

   Zhao, Qishen; Martin, Christopher; Chen, Dongmei; Li, Wei (July 2022, Proceedings of the 2022 International Symposium on Flexible Automation)

   Roll-to-roll(R2R) peeling is an innovative method that transfers flexible electronics and 2D materials from the flexible substrate where they are grown to the end-use substrate. This process enables the full potential of R2R 2D material fabrication methods in a continuous, high-throughput, and environment friendly manner. During the R2R peeling process, the device patterning causes periodic changes in the adhesion energy between the device and substrate. This periodic disturbance can degrade the quality of the final product if not properly controlled. Current control methods used for the R2R peeling process do not explicitly reject the periodic disturbance. It is therefore desirable to develop a controller that is capable of performing periodic disturbance rejection. This paper presents a model-based repetitive controller that integrates a frequency estimation of the disturbance into the R2R peeling control to maintain the optimal peeling process performance. A linear estimator using system identification techniques is employed. The simulation results show that the developed controller achieves better R2R process performance when compared to a conventional model-based controller. 

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4. The Line Speed Effect in Roll-to-Roll Dry Transfer of Chemical Vapor Deposition Graphene,

   Hong, N. (December 2021, 2021 International Conference on Micro- and Nano-devices Enabled by R2R Manufacturing)

   Sreenivasan, S.V. (Ed.)

   A roll-to-roll (R2R) technique is especially desirable for transfer of chemical vapor deposition (CVD) graphene towards high-speed, low-cost, renewable, and environmentally friendly manufacturing of graphene-based electronic devices, such as flexible touchscreens, field effect transistors and organic solar cells. A R2R graphene dry transfer system is recently developed. Monolayer graphene is transferred from a copper growth substrate to a polymer backing layer by mechanical peeling. In this work, we present an experimental study to examine the effects of line speed of the mechanical peeling process on the transferred graphene quality. It is shown that the effect of line speed is not monotonic, and an optimal speed exists to yield the highest and most consistent electrical conductivity of transferred graphene among the process conditions studied. This study provides understanding of process parameter effects and demonstrates the potential of the R2R dry transfer process for large-scale CVD graphene toward industrial applications. 

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5. A Review of Advanced Roll-to-Roll Manufacturing: System Modeling and Control

   https://doi.org/10.1115/1.4067053  

   Martin, Christopher; Zhao, Qishen; Patel, Anjali; Velasquez, Enrique; Chen, Dongmei; Li, Wei (April 2025, Journal of Manufacturing Science and Engineering)

   Abstract Roll-to-roll (R2R) manufacturing is a highly efficient industrial method for continuously processing flexible webs through a series of rollers. With advancements in technology, R2R manufacturing has emerged as one of the most economical production methods for advanced products, such as flexible electronics, renewable energy devices, and 2D materials. However, the development of cost-effective and efficient manufacturing processes for these products presents new challenges, including higher precision requirements, the need for improved in-line quality control, and the integration of material processing dynamics into the traditional web handling system. This paper reviews the state of the art in advanced R2R manufacturing, focusing on modeling and control, and highlights research areas that need further development. 

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