Cheng-Yao Lo

Cheng-Yao Lo

Associate Professor National Tsing Hua University

Presentation Title:

Asymmetrical Strain Detection in Roll-to-Roll System by Thermoresistive Sensor

Time: TBD

Presentation Abstract:

A sequential procedure comprising inkjet patterning, flash light sintering, and
thermoresistive strain sensing steps was proposed and examined in this work. These three steps were roll-to-roll competitive, which provided a solution to visualize strains in transparent polymeric substrates. Unlike previous demonstrations that only symmetric strains (either tensile or compressive) were supported, this work demonstrated its capability on detecting asymmetric tensile strains, which was exactly the consequence of an off-axis roller in the system.

Comprehensive simulation, experiment, and analysis were conducted in this work and the results indicated that both current and voltage supported the sensing mechanism (Fig. 1).The smallest detectable strain was 0.0625% in both symmetric tension and compression.The gauge factor based on resistance change was 0.0271 and 0.0111 for tension and compression, respectively; and that based on temperature change was 1.25 and 1.18 for tension and compression, respectively. This non-contact sensing mechanism avoided various drawbacks in conventional contact-sensing strain gauges.

Asymmetric strain was realized by anisotropically stretching the thermoresistive sensor,which left a trapezoid tensile deformation. The resistors distributed in the active area in the sensor reflected cumulative strains, which exhibited temperature gradients and corresponded to asymmetric strain distribution (Fig. 2). These results proved that not only the sensor followed expected Joule heating effect but also implied that prediction on temperatures (strains) that was not demonstrated in this work was possible for other applications.


Cheng-Yao Lo received his Ph.D. degree in Electrical Engineering from The University of Tokyo, Japan, in 2009. He was a senior R&D process integration engineer in Taiwan Semiconductor Manufacturing Company (TSMC) during 2001-2005 and he was a visiting researcher in VTT Technical Research Centre of Finland during 2006-2009. He joined the Institute of NanoEngineering and MicroSystems, National Tsing Hua University since 2010; and the Department of Power Mechanical Engineering since 2012. He and his group recently focus on the following topics: Flexible printed electronics devices, reliability analysis of organic/inorganic materials, and roll-to-roll (reel-to-reel, R2R) printing process development.

Company Profile:

National Tsing Hua University is ranked one of the best universities in Taiwan, in which more than 600 faculties perform researches in nine colleges.The Department of Power Mechanical Engineering in College of Engineering was ranked top 50 on the world.