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Breakthrough in Transient Electronic Manufacturing Field

 Research

Professor Huang Xian from Tianjin University and his collaborator Professor Pan Heng from Missouri University of Science and Technology have recently released two papers entitled ‘Mechanically Milled Irregular Zinc Nanoparticles for Printable Bioresorbable Electronics’ and ‘Low-Cost Manufacturing of Bioresorbable Conductors by Evaporation–Condensation-Mediated Laser Printing and Sintering of Zn Nanoparticles’. The former has been published as cover story on Small, a peer-reviewed interdisciplinary journal. The latter has been released on Advanced Material, an international scientific journal, covering materials science.  

The paper ‘Mechanically Milled Irregular Zinc Nanoparticles for Printable Bioresorbable Electronics’ published on Small as cover story 

The publications introduce two techniques that can achieve bioresorbable transient electronics through photonic sintering and evaporation condensation. The first technique uses a fine-tuned ball milling approach to obtain irregular zinc nanoparticles that are suitable for printable electronics, and achieved highly conductive zinc patterns through photonic sintering. During the ball milling process, zinc micro particles reduce their sizes into ~100 nm through the impact and sliding of grinding balls, while the aggregation of the particles is prevented by surface polymerization. The milled nanoparticles can absorb photons emitted through a broadband high-intensity xenon lamp, resulting in the localized particle melting followed by the formation of a conductive matrix and the elimination of surface polymer. As a result, highly conductive transient metal patterns can be achieved on a bioresorbable polymer substrate at room temperature and atmosphere conditions.  


Process to acquire irregular Zn nanoparticles and achieve conductive patterns 

In the second technique, conductive transient metal patterns are achieved through laser scanning. When the laser scans across a glass slides predeposited with zinc nanoparticles, the zinc atoms escape from the surface oxidation shell of the nanoparticles, and form a vapor of zinc atoms due to laser heating. The zinc vapor eventually becomes supersaturated and condenses on a bioresorbable film in contact with the glass slides. The deposition rate of the zinc can be controlled by the distance between the glass slides and the bioresorbable films, and the conductivity of the patterns can be controlled by the laser power and the scanning speed. 


Technical illustration and schematics of laser printing process, and photograph of dissolving process of Zn patterns on Na-CMC substrate in distilled water 

There are a number of applications for bioresorbable electronic devices, including implantable post-surgical monitoring of organ, tissue, implant, and wound health without the need for surgery to remove them. These devices reduce the risk of infection and complications during and after the surgery processes. As time goes by, the biodegradable electronic devices will be dissolved and absorbed by the body after their task is finished. And Zn, as a microelement, is nontoxic to our bodies. With regard to environmental protection, bioresorbable circuits can be used to replace current built-to-last circuits, and can degrade without releasing harmful toxins, allowing rapid recycling of electronic components on the circuits and further reduction in environmental pollution due to unsustainable recycling procedures. Despite the heavy demand of bioresorbable electronic devices, they have not yet been mass produced.  

Currently, bioresorbable electronics is predominantly realized by complex and time-consuming anhydrous fabrication processes. The intention of the first technique which obtains Zn nanoparticles through ball milling and processes them through photonic sintering is that it may potentially lead to a mass fabrication method for bioresorbable electronics using printable electronic technology. As for the second technique, it improves the manufacturing approach for bioresorbable conductors on bioresorbable polymer substrates by evaporation–condensation-mediated laser printing and sintering of Zn nanoparticles. Both techniques will promote the applications of bioresorbable electronics in healthcare, environmental protection, and consumer electronics by contributing various environmentally friendly sensors and circuits.  

Huang is a professor from the Biomedical Engineering School in Tianjin University (TJU). After having received his Bachelor and Master of Science from TJU, he further pursued his studies and obtained a PHD in Mechanical Engineering from Columbia University. Furthermore, he has been a postdoctoral scholar at the University of Illinois at Urbana-Champaign and an assistant professor at Missouri University of Science and Technology. Based on his extensive research, Huang has been chosen as a member of the 1000 Talented Youth Scholar Plan in 2015 held by China’s central government.  

Huang’s laboratory, the Laboratory of Biological Microfluidics and Flexible Electronics of Tianjin University is the first open-platform for designing, fabricating, and characterizing microfluidic and flexible electronic devices in TJU. It conducts research in the cutting edge areas of biological signal sensing based on microfluidic devices, flexible electronic devices, and biosensors. His laboratory represents a platform of enormous potential in scientific research.  

By: Wang Huiting

Cover Designer: Zhang Jieyu

Editors: Qin Mian and Christopher Peter Clarke