Tech Briefs Magazine - October 2021 - 39

Manufacturing & Prototyping
Sonolithography Uses Ultrasound for Non-Contact
Patterning on Surfaces
The new printing method coaxes particles and droplets into precise patterns using the
power of sound.
University of Bath, United Kingdom
esearchers have developed a way to
coax microscopic particles and
droplets into precise patterns by harnessing
the power of sound in air. The
implications for printing, especially in
the fields of medicine and electronics,
are far-reaching.
R
The scientists created precise, predetermined
patterns on surfaces from
aerosol droplets or particles using computer-controlled
ultrasound. The technique,
called sonolithography, patterns
dense clouds of material in air at scale
and algorithmically controls how the
material settles into shapes. The re -
searchers believe the technique could
revolutionize printing, improving the
speed, cost, and precision of non-contact
patterning techniques in air.
Sonolithography enables gentle, noncontact,
and rapid patterning of cells
and biomaterials on surfaces. Tissue en -
gineering can use biofabrication methods
to build defined structures of cells
and materials.
The objects being manipulated are
the size of water drops in clouds. The
Ultrasound and computer algorithms control how material settles into shapes.
ability to move such small things with
such fine control could allow the direction
of aerosol sprays with extreme precision
in applications such as drug delivery
or wound healing.
Beyond biomedicine applications, the
technique is applicable to a variety of
materials. Printed electronics is another
area the team is developing, with sonolithography
being used to arrange conductive
inks into circuits and components.
For more information, contact Vittoria
D'Alessio at vda26@bath.ac.uk; +44 (0) 1225
383135.
Manufacturing Technique Yields Flexible Electronics
With this advance, so-called " flextronics " move closer to reality.
Stanford University, Palo Alto, California
ltrathin, flexible computer circuits
have been an engineering goal for
years but technical hurdles have prevented
the degree of miniaturization
necessary to achieve high performance.
Now, researchers have invented a manufacturing
technique that yields flexible,
atomically thin transistors less than 100
nanometers in length - several times
smaller than previously possible.
Flexible electronics promise bendable,
shapeable, yet energy-efficient computer
circuits that can be worn on or implanted
in the human body to perform myriad
U
Tech Briefs, October 2021
Cov
health-related tasks. Among suitable
materials for flexible electronics, twodimensional
(2D) semiconductors have
shown promise because of their excellent
mechanical and electrical properties,
even at the nanoscale, making them
better candidates than conventional silicon
or organic materials.
The engineering challenge to date
has been that forming these almost
impossibly thin devices requires a
process that is far too heat-intensive for
the flexible plastic substrates. These
flexible materials would simply melt
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ToC
and decompose in the production
process. The solution is to do it in steps,
starting with a base substrate that is anything
but flexible.
Atop a solid slab of silicon coated with
glass, researchers formed an atomically
thin film of the 2D semiconductor
molybdenum disulfide (MoS2) overlaid
with small nano-patterned gold electrodes.
Because this step is performed
on the conventional silicon substrate,
the nanoscale transistor dimensions can
be patterned with existing advanced
patterning techniques, achieving a reso39
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Tech Briefs Magazine - October 2021

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