Tech Briefs Magazine - March 2021 - 50

Manufacturing &
Prototyping
Typically carbon-based with a strong
broadband absorption, adding these sensitizers to the polymer powders increases
the conversion of incident light to heat,
which means greater print speeds. Carbonbased sensitizers, however, can only produce black or gray objects. To create white
or colorful prints, visibly transparent
equivalents are needed.
A solution for overcoming color
restrictions in this method uses plasmonic nanoparticles. Researchers designed

gold nanoparticles coated with silica as a
photothermal sensitizer to allow a rapid
sintering of polymer powders into 3D
objects by having the nanoparticles
strongly absorb in the near-infrared,
while only minimally interacting with visible light. At resonance, these composites
showed greatly improved light-to-heat
conversion compared with equivalent
composites and could be sintered using
low-power light sources. While these particles showed to be very efficient for the

WO3

GNRs
PA12

Laser sintered samples using PA12 powder and gold nanoparticles (GNRs), tungsten oxide (WO3),
and carbon-black-based sensitizers (CB).

rapid fabrication of colored 3D objects,
they proved to have certain limitations
when trying to print 3D objects in pure
white or multiple colors with high color
fidelity across a large hue range, affecting
the quality of the coloration of prints in
high concentrations.
Thus, the researchers created a new sensitizer that has overcome these problems.
The team used nanoparticles made of
tungsten oxide (WO3) as the photothermal sensitizers for polymer powders. The
nanoparticles comprise low-cost elements,
which make them easy and cheap to fabricate. They are colorless at high concentrations and have a strong absorption in the
near-infrared region, proving their capability of turning light into heat at a fast
rate. In addition, they can be efficiently
turned on or off with electricity or ultraviolet radiation. They are stable at very high
temperatures and demonstrate a heatingto-color change rate superior to other
available sensitizers. When mixed with
other color inks, these nanoparticles have
been able to reproduce the same shades of
color as the original powders, maintaining
the color purity of the samples.
For more information, contact Dr. Silvia
Carrasco, Knowledge and Technology Transfer Director, at Silvia.Carrasco@icfo.eu; +34
935534090.

Laser Printing Technology for Waterproof E-Textiles
The next generation of waterproof smart fabrics can be laser-printed and made in minutes.
RMIT University, Melbourne, Australia

he smart fabrics industry has applications in wearable devices for the consumer, healthcare, and defense sectors
- from monitoring vital signs of patients, to tracking the location and
health status of soldiers in the field, and
monitoring pilots or drivers for fatigue.
Smart textiles with built-in sensing, wireless communication, or health monitoring technology, however, call for robust
and reliable energy solutions.
Current methods of smart textile
energy storage, like stitching batteries
into garments or using e-fibers, can be
heavy and have capacity issues. Such
electronic components can also suffer
short-circuits and mechanical failure
when they come into contact with sweat
or moisture from the environment.
A scalable method was developed for
rapidly fabricating textiles that are
embedded with energy storage devices.

The new technology rapidly fabricates textiles embedded with energy storage devices.

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Tech Briefs Magazine - March 2021

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