Tech Briefs Magazine - September 2024 - 33

The lab's DNGE prototype 'finger' with rigid 'bones' surrounded by flexible
'flesh.' (Image: Adrian Alberola)
a bioprinter to create a desired structure. The precursor is
polymerized within the 3D-printed structure, creating a second
elastomeric network that rigidifies the entire object.
While the composition of the first network determines the
structure's stiffness, the second determines its fracture toughness,
meaning that the two networks can be fine-tuned independently
to achieve a combination of stiffness, toughness,
and fatigue resistance. The use of elastomers over hydrogels
- the material used in state-of-the-art approaches - has the
added advantage of creating structures that are water-free,
making them more stable over time. To top it off, DNGEs can
be printed using commercially available 3D printers.
" The beauty of our approach is that anyone with a standard
bioprinter can use it, " Amstad emphasized.
One exciting potential application of DNGEs is in devices
for motion-guided rehabilitation, where the ability to support
movement in one direction while restricting it in another
could be highly useful. Further development of DNGE
technology could result in prosthetics, or even motion guides
to assist surgeons. Sensing remote movements, for example
in robot-assisted crop harvesting or underwater exploration,
is another area of application.
Amstad said that the Soft Materials Lab is already working
on the next steps toward developing such applications by integrating
active elements, such as responsive materials and
electrical connections, into DNGE structures.
For more information, contact Celia Luterbacher at celia.
luterbacher@epfl.ch; +41-216-938-759.
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An example of DNGEs (3D-printable double network granular elastomers).
(Image: Titouan Veuillet)
finger was printed to deform in a pre-defined way, demonstrating
the technology's potential to manufacture devices
that are sufficiently supple to bend and stretch, while remaining
firm enough to manipulate objects.
With these advantages, the researchers believe that DNGEs
could facilitate the design of soft actuators, sensors, and wearables
free of heavy, bulky mechanical joints. The research has
been published in the journal Advanced Materials.
The key to the DNGEs' versatility lies in engineering two
elastomeric networks. First, elastomer microparticles are produced
from oil-in-water emulsion drops. These microparticles
are placed in a precursor solution, where they absorb
elastomer compounds and swell up. The swollen microparticles
are used to make a 3D printable ink, which is loaded into
Tech Briefs, September 2024
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Tech Briefs Magazine - September 2024

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