Medical Design Briefs - July 2021 - 28

pany with additional process modifications
performed in the Columbia Nano
Initiative cleanroom and the City
University of New York Advanced
Science Research Center (ASRC)
Nanofabrication Facility.
" This is a nice example of 'more than
Moore' technology - we introduced new
materials onto standard complementary
metal-oxide-semiconductor to provide
new function. In this case, we added
piezoelectric materials directly onto the
integrated circuit to transducer acoustic
energy to electrical energy, " says Shepard.
Konofagou adds, " Ultrasound is continuing
to grow in clinical importance
as new tools and techniques become
available. This work continues this
trend. "
The team's goal is to develop chips
that can be injected into the body with a
hypodermic needle and then communicate
back out of the body using ultrasound,
providing information about
something they measure locally. The
current devices measure body temperature,
but there are many more possibilities
the team is working on.
The study was supported in part by a
grant from the W. M. Keck Foundation
and by the Defense Advanced Research
Projects Agency (DARPA) under Con -
tract HR0011-15-2-0054 and Co -
operative Agreement D20AC00004.
Chen Shi and Kenneth L. Shepard are
listed as inventors on a provisional
patent filed by Columbia University
(Patent Appli cation No. 15/911,973).
The other authors declare no competing
interests.
Reference
1. C. Shi, et al., " Application of a sub-0.1mm3
implantable mote for in vivo realtime
wireless temperature sensing, " Science
Advances, May 7, 2021.
This article was written by Holly Evarts,
Columbia University. For more information,
visit www.engineering.columbia.edu.
3D Printing Technique Creates Intricate Medical
Implants
The biomedical structures
advance the development
of new technologies for
regrowing bones and
tissue.
RMIT University
Melbourne, Australia
The emerging field of tissue engineering
aims to harness the human body's
natural ability to heal itself, to rebuild
bone and muscle lost to tumors or
injuries. A key focus for biomedical engineers
has been the design and development
of 3D printed scaffolds that can be
implanted in the body to support cell
regrowth. But making these structures
small and complex enough for cells to
thrive remains a significant challenge.
Enter an RMIT University-led research
team, collaborating with clinicians at St
Vincent's Hospital Melbourne, who
have overturned the conventional 3D
printing approach. Instead of making
the bioscaffolds directly, the team 3D
printed molds with intricately patterned
cavities then filled them with
biocompatible materials, before dissolving
the molds away.
Using the indirect approach, the team
created fingernail-sized bioscaffolds full
of elaborate structures that, until now,
were considered impossible with standard
3D printers. Lead researcher Dr.
Cathal O'Connell says the new biofabrication
method was cost-effective and eas28
Intro
Cov
A
tiny and intricate biomedical structure created with the new technique. (Credit: RMIT)
ily scalable because it relied on widely
available technology.
" The shapes you can make with a standard
3D printer are constrained by the
size of the printing nozzle - the opening
needs to be big enough to let material
through and ultimately that influences
how small you can print, "
O'Connell, a Vice-Chancellor's Post doc -
toral Fellow at RMIT, says.
" But the gaps in between the printed
material can be way smaller, and far
more intricate.
" By flipping our thinking, we essentially
draw the structure we want in the
empty space inside our 3D printed
mold. This allows us to create the tiny,
complex microstructures where cells will
flourish. "
www.medicaldesignbriefs.com
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■ Versatile Technique
O'Connell says other approaches were
able to create impressive structures, but
only with precisely tailored materials,
tuned with particular additives or modified
with special chemistry.
" Importantly, our technique is versatile
enough to use medical grade materials
off-the-shelf, " he says. " It's extraordinary
to create such complex shapes
using a basic 'high school' grade 3D
printer.
That really lowers the bar for
entry into the field, and brings us a significant
step closer to making tissue
engineering a medical reality. "
The research, published in Advanced
Materials Technologies, was conducted
at BioFab3D@ACMD, a state-of-the-art
bioengineering research, education,
Medical Design Briefs, July 2021
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Medical Design Briefs - July 2021

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