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1. 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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2. Boolean and Elementary Algebra with a Roll‐To‐Roll Printed Electrochemical Memristor

   https://doi.org/10.1002/admt.202101108  

   Grant, Benjamin; Bandera, Yuriy; Foulger, Stephen_H; Vilčáková, Jarmila; Sáha, Petr; Pfleger, Jiří (October 2021, Advanced Materials Technologies)

   Abstract A non‐volatile conjugated polymer‐based electrochemical memristor (cPECM), derived from sodium 4‐[(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐2‐yl)methoxy]butane‐2‐sulfonate (S‐EDOT), is fabricated through roll‐to‐roll printing and exhibited neuromorphic properties. The 3‐terminal device employed a “read” channel where conductivity of the water‐soluble, self‐doped S‐PEDOT is equated to synaptic weight and was electrically decoupled from the programming electrode. For the model system, a +2500 mV programming pulse of 100 ms duration resulted in a 0.136 μS resolution in conductivity change, giving over 1000 distinct conductivity states for one cycle. The minimum programming power requirements of the cPECM was 0.31 pJ mm⁻²and with advanced printing techniques, a 0.1 fJ requirement for a 20 μm device is achievable. The mathematical operations of addition, subtraction, multiplication, and division are demonstrated with a single cPECM, as well as the logic gates AND, OR, NAND, and NOR. This demonstration of a printed cPECM is the first step toward the implementation of a mass produced electrochemical memristor that combines information storage and processing and may allow for the realization of printable artificial neural networks. 

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3. Roll‐to‐Roll Dry Transfer of Large‐Scale Graphene

   https://doi.org/10.1002/adma.202106615  

   Hong, Nan; Kireev, Dmitry; Zhao, Qishen; Chen, Dongmei; Akinwande, Deji; Li, Wei (November 2021, Advanced Materials)

   Abstract A major challenge for graphene applications is the lack of mass production technology for large‐scale and high‐quality graphene growth and transfer. Here, a roll‐to‐roll (R2R) dry transfer process for large‐scale graphene grown by chemical vapor deposition is reported. The process is fast, controllable, and environmentally benign. It avoids chemical contamination and allows the reuse of graphene growth substrates. By controlling tension and speed of the R2R dry transfer process, the electrical sheet resistance is achieved as 9.5 kΩ sq⁻¹, the lowest ever reported among R2R dry transferred graphene samples. The R2R dry transferred samples are used to fabricate graphene‐based field‐effect transistors (GFETs) on polymer. It is demonstrated that these flexible GFETs feature a near‐zero doping level and a gate leakage current one to two orders of magnitude lower than those fabricated using wet‐chemical etched graphene samples. The scalability and uniformity of the R2R dry transferred graphene is further demonstrated by successfully transferring a 3 × 3 in²sample and measuring its field‐effect mobility with 36 millimeter‐scaled GFETs evenly spaced on the sample. The field‐effect mobility of the R2R dry transferred graphene is determined to be 205 ± 36 cm² V⁻¹. 

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4. The air-gap PAD: a roll-to-roll-compatible fabrication method for paper microfluidics

   https://doi.org/10.1039/d2lc01164f  

   Roller, Rachel M.; Rea, Angela; Lieberman, Marya (March 2023, Lab on a Chip)

   Paper-based analytical devices (PADs) offer a low-cost, user-friendly platform for rapid point-of-use testing. Without scalable fabrication methods, however, few PADs make it out of the academic laboratory and into the hands of end users. Previously, wax printing was considered an ideal PAD fabrication method, but given that wax printers are no longer commercially available, alternatives are needed. Here, we present one such alternative: the air-gap PAD. Air-gap PADs consist of hydrophilic paper test zones, separated by “air gaps” and affixed to a hydrophobic backing with double-sided adhesive. The primary appeal of this design is its compatibility with roll-to-roll equipment for large-scale manufacturing. In this study, we examine design considerations for air-gap PADs, compare the performance of wax-printed and air-gap PADs, and report on a pilot-scale roll-to-roll production run of air-gap PADs in partnership with a commercial test-strip manufacturer. Air-gap devices performed comparably to their wax-printed counterparts in Washburn flow experiments, a paper-based titration, and a 12-lane pharmaceutical screening device. Using roll-to-roll manufacturing, we produced 2700 feet of air-gap PADs for as little as $0.03 per PAD. 

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5. Optimal Control of a Roll-to-Roll Dry Transfer Process With Bounded Dynamics Convexification

   https://doi.org/10.1115/1.4066456  

   Martin, Christopher; Zhao, Qishen; Bakshi, Soovadeep; Velasquez, Enrique; Li, Wei; Chen, Dongmei (May 2025, Journal of Dynamic Systems, Measurement, and Control)

   Abstract For efficient roll-to-roll (R2R) production of flexible electronic components, a precise R2R transfer peeling process is essential, requiring accurate modeling and control. This paper introduces a novel approach to confining the dynamics of a nonlinear R2R mechanical peeling system within a convex set known as a norm-bounded linear differential inclusion (NLDI). This method utilizes constraints on uncertain system variables to create a tighter NLDI representation compared to other convexification techniques. Moreover, it offers drastically reduced computational cost compared to previous methods applied to convexify the R2R peeling system. The NLDI is employed to generate an H∞-optimal controller for the R2R peeling system, and both simulations and experiments demonstrate better dynamic performance compared to other controllers for R2R transfer. 

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