Applications for circuits and devices printed on flexible substrates abound, ranging from wearable diagnostic sensors to large area, roll-up displays. Continuous printing processes are attractive for manufacturing flexible electronics. However, two challenges typically arise in this pursuit: (1) creating small feature sizes, and (2) achieving registration of multiple functional layers. This presentation will cover our efforts to address these challenges using a new approach – Self-Aligned Capillarity-Assisted Lithography for Electronics (or SCALE). SCALE involves imprinting a multilevel open network of reservoirs, capillaries and device structures into a UV-curable coating deposited on a flexible substrate, delivering electronically functional inks into the reservoirs by inkjet printing, and using capillarity to selectively fill capillaries and device structures attached to the reservoirs. The single imprint step creates all the structural features needed in the devices and capillary flow creates self-aligned, multimaterial devices. To-date we have used SCALE to create conductive networks, resistors, capacitors, diodes and transistors. This presentation will show advances in device architecture and performance, and explore the key processing steps. Special attention will be given to the continuous roll-to-roll imprinting process, experiments and visualizations of liquid flow in open capillary channels, and unique flow control methods such as a microfluidic diode.
Lorraine F. Francis is Professor of Chemical Engineering and Materials Science and currently holds the 3M Chair in Experiential Learning in the College of Science and Engineering at the University of Minnesota. She received a B.S. in Ceramic Engineering from Alfred University in 1985, and M.S. and Ph.D. in Ceramic Engineering from the University of Illinois in 1987 and 1990, respectively. She then joined the University of Minnesota. Professor Francis has research interests broadly in the area of materials processing, including coating and printing processes and microstructure development studies. She is also very involved in undergraduate education, including developing a project-based learning class for freshmen and authoring a textbook. Professor Francis has received several awards. In 2019, she was named College of Science and Engineering Distinguished Professor, and in 2014 she received the Horace T. Morse - University of Minnesota Alumni Association Award for Outstanding Contributions to Undergraduate Education.
Reception at 2:45 p.m. in the Howey Physics Atrium.