"Development of Inkjet Printing Processes for Flexible Sensors and Electronics on Temperature-Sensitive Substrates"
Speaker: Dr. Chris Zorman, Professor and Senior Associate Dean, Case Western Reserve University
Day and Date: Friday, October 11th, 2024
Time: 10:45-11:45 AM
Location: HST 101
Abstract:
Additive manufacturing methods based on direct-write printing have emerged as a sustainable alternative to conventional subtractive methods to fabricate electrical conductors for flexible electronics based on photolithography and etching. From a commercial perspective, inkjet printing leads all methods of direct-write printing due to the availability of large-scale, high-throughput printing systems combined with reliable sources of commercially available inks. From a prototyping perspective, inkjet printing offers an excellent balance of resolution, print speed, scalability and design-to-part turnaround time. However, further expansion of inkjet printing, in particular towards biomedical applications is currently limited by two significant impediments, namely the limited variety of metals that are currently available in suitable inks and the relatively high temperatures that are required after printing to form conducting structures.
In this talk, I will review our work in developing two methods to address these shortcomings. The first method utilizes a low-pressure Ar plasma to form conductive metal structures from particle-free inks comprised of a metal salt as the precursor and ethylene glycol as the ink solvent. During Ar plasma treatment, conductive metal structures are formed at substrate temperatures between ~39°C and ~140°C depending on the ink composition. Such low substrate temperatures enable the fabrication of devices on temperature-sensitive substrates such as paper and cellophane. We have successfully used this approach to fabricate a wide range of devices and sensors, including RC filters, RTDs, strain gauges, and chemical sensors from a wide variety of metals including Ag, Au, Cu, Pt, Pd, Pb, Bi and Sn. The second method uses inkjet printing to selectively dispense an acetic acid reducing agent on screen printed Zn structures. The reducing agent initiates chemical deoxidation of the native zinc oxide on Zn microparticles, facilitating the formation of connected Zn structures by electrochemical sintering at room temperature. The spatial and volume control offered by an inkjet printer enables the side-by-side fabrication of resistors and conductors from the same screen printed layer. To demonstrate the effectiveness and versatility of this method, RC-filters were fabricated on paper substrates from a single layer of Zn.
Personal Bio:
Christian A. Zorman, PhD is the F. Alex Nason Professor I in the Department of Electrical, Computer, and Systems Engineering at Case Western Reserve University with secondary faculty appointments in the Department of Biomedical Engineering and the Department of Mechanical and Aerospace Engineering. He also serves as Senior Associate Dean in the Case School of Engineering and Director of the Microfabrication Laboratory. He has authored over 300 publications in peer-reviewed journals and conference proceedings in areas related to micro- and nanotechnology. He specializes in the development of emerging materials and nonconventional processing/fabrication techniques for micro/nanosystems, with a focus on applications in aerospace and human health. He received a B.S. cum laude in physics and a B.A. cum laude in economics from the Ohio State University in 1988, followed by M.S. and Ph.D. in physics from Case Western Reserve University in 1991 and 1994, respectively. He is a Fellow of the AVS and Senior Member of IEEE. He serves as a Topical Editor for IEEE Sensors Letters. In 2009, Professor Zorman received CWRU’s John S. Diekhoff Award for Excellence in Graduate Mentoring
This event is free and open to the public. Please reach out to the Department of Bioengineering's team (inbioe@lehigh.edu) with any questions or comments.