Roll to Roll Manufacturing and In-Line Imaging and Characterization of Functional Films

Abstract Roll-to-roll manufacturing is a promising platform to produce low cost, high quality electrical components and sensors for Internet of Things (IoT) applications. Within the roll-to-roll laboratories at Purdue University, a range of processes and machines have been developed to: 1) print patterns of conductive and sensing materials for use in electronic sensors, 2) cast films precisely with integrated functional materials, and 3) monitor quality of the printing and casting processes in-line in real time. A major development is the custom-designed and built Maxwell coating machine, which has enabled substantial quality improvements in slot-die coatings, as demonstrated by precise in-line thickness monitoring and imaging. As an illustrative example, we will show how we converted a design for a printed ion-selective electrode from a batch process to a roll-to-roll process. In-line process monitoring of coating thickness allowed us to identify high variability in the coating thickness due to an interaction between underlying printed electrodes and the drying process. By modifying the drying process, we demonstrated a substantial improvement as evidenced by the same in-line measurement technique. The overall process integrates several existing machines and processes in a novel way to create functional parts continuously, with data on individual parts gathered in real time.