SITE SEARCH:
video overview
ADS

IIr Associates, Inc.
Publisher of The Virginia Engineer

Print-Publishing Services
Web Site Design-Coding-Hosting
Business Consulting

Phone: (804) 779-3527
sales@iirassoc.com
iirassoc.com

NEWS
Researchers Develop New Microparticles To Foil Counterfeiters
December 30, 2020

With each passing day, the arms race between legitimate enterprises and counterfeiters heats up. Each side seeks an advantage as manufacturers seek out new technologies to stay one step ahead and counterfeiters seek new approaches to circumvent these measures.

Now, according to information provided by the American Chemical Society (ACS), researchers reporting in ACS Nano have developed tiny “Janus balls” that show their colored side under a magnetic field. According to the researchers, these microparticles could be useful in inks for anti-counterfeiting tags, which could be verified with an ordinary magnet.

Janus, the two-faced god of transitions in ancient Roman mythology, served as the impetus for the research as so-called Janus balls are microspheres that have two sides with distinct properties. Shin-Hyun Kim, an associate professor in the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology, and his colleagues wanted to make Janus balls out of two unmixable resins: one that contained magnetic nanoparticles, and another that contained silica particles. The magnetic side of the ball would also contain carbon black, causing that hemisphere to appear dark, whereas the silica particles on the other side of the ball would self-assemble into a crystalline lattice, producing structural colors. The result would be tiny balls that normally have their black sides facing up, except when a magnetic field causes them to flip to their colorful sides.

With funding provided by the National Research Foundation of Korea, the researchers created Janus balls by using a microfluidic device to unite drops of the two resins, with a surfactant added to stabilize the joined drops into a spherical shape. Because the silica-containing colored side of the drops was heavier than the black magnetic side, the force of gravity caused the black side to spontaneously face upward, like a roly-poly toy, when the balls were placed in water. Then, the researchers permanently aligned the magnetic nanoparticles in the balls in the same direction. By applying a magnetic field in the opposite direction, they could flip the balls to their colored sides. The researchers made red and green Janus balls by using different sizes of silica particles, with their magnetic nanoparticles aligned in opposite directions. By changing the direction of the applied magnetic field, they could change the colors of 3D-printed chameleon and butterfly shapes. According to the researchers, using different colors and orientations of Janus balls in inks could produce sophisticated, user-interactive anti-counterfeiting tags.


  ------   News Item Archive  -----  
 
 
The Virginia Engineer on facebook
The Virginia Engineer RSS Feed