Technical Abstracts
In Case You Missed It
Advanced Materials

“Metal Oxide Semiconductor Nanomembrane-Based Soft Unnoticeable Multifunctional Electronics for Wearable Human-Machine Interfaces”

Authors: Kyoseung Sim, Zhoulyu Rao, et al; cyu13@central.uh.edu.

Abstract: Wearable human-machine interfaces (HMIs) are an important class of devices that enable human and machine interaction and teaming. Recent advances in electronics, materials, and mechanical designs have offered avenues toward wearable HMI devices. However, existing wearable HMI devices are uncomfortable to use and restrict the human body’s motion, show slow response times, or are challenging to realize with multiple functions. Here, the authors report sol-gel-on-polymer-processed indium zinc oxide semiconductor nanomembrane-based ultrathin stretchable electronics with advantages of multifunctionality, simple manufacturing, imperceptible wearing, and robust interfacing. Multifunctional wearable HMI devices range from resistive random-access memory for data storage to field-effect transistors for interfacing and switching circuits, to various sensors for health and body motion sensing, and to microheaters for temperature delivery. HMI devices can be not only seamlessly worn by humans but also implemented as prosthetic skin for robotics, which offer intelligent feedback, resulting in a closed-loop HMI system. (Science Advances, Aug. 2, 2019; https://advances.sciencemag.org/content/5/8/eaav9653).

Flexible Electronics

“Heat-Free Fabrication of Metallic Interconnects for Flexible/Wearable Devices”

Authors: Andrew Martin, Martin Thuo, et al; mthuo@iastate.edu

Abstract: Exploiting interfacial excess (Γ), Laplace pressure jump (ΔP), surface work, and coupling them to surface reactivity have led to the synthesis of undercooled metal particles. Metastability is maintained by a core-shell particle architecture. Fracture of the thin shell leads to solidification with concomitant sintering. Applying Scherer’s constitutive model for load-driven, viscous sintering on the undercooled particles implies they can form conductive traces. Combining metastability to eliminate heat and robustness of viscous sintering, an array of conductive metallic traces can be prepared, leading to a plethora of devices on various flexible and/or heat-sensitive substrates. Besides mechanical sintering, chemical sintering can be performed, which negates the need for either heat or load. In the latter, connectivity is hypothesized to occur via a Frenkel’s theory of a sintering-type mechanism. This work reports heat‐free, ambient fabrication of metallic conductive interconnects and traces on all types of substrates. (Advanced Functional Materials, July 15, 2019; https://doi.org/10.1002/adfm.201903687)

Solder Materials

“Effects of In and Zn Double Addition on Eutectic Sn-58Bi Alloy”

Authors: Shiqi Zhou, Yu-An Shen, Hiroshi Nishikawa, Tiffani Uresti, Vasanth C. Shunmugasamy, and Bilal Mansoor; charleszhou1992@gmail.com.

Abstract: The effects of 0.5 wt. % In as well as 0.5 wt. % In and 1 wt. % Zn double (In & Zn) additions to eutectic Sn58Bi alloy on the microstructure and mechanical properties were studied before and after thermal aging. Newly designed In & Zn-added Sn58Bi alloy showed much finer microstructure than eutectic Sn58Bi and In-added Sn58Bi alloys. The elongation improvements of 36% and 41% before and after 1,008 hr. aging were obtained in In & Zn-added Sn58Bi alloy compared to eutectic Sn58Bi alloy. In-induced solid solution softening (SSS) effect on Sn phase was revealed by nanoindentation tests. A hardness decrease and a large creep displacement were obtained in both In- and In & Zn-added Sn58Bi. The effects of Zn and In combined were responsible for the elongation improvement of In & Zn-added Sn58Bi. (IEEE Electronic Components and Technology Conference, May 2019)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.