Imagine camouflage that renders a subject
almost invisible; prosthetic limbs that look and feel like real appendages; smartphone
battery power that’s embedded throughout the thin fabric of your clothing; windows
that direct light to different parts of the room throughout the day. All of these
ideas and much more may be possible with a new age of material science that is now
unfolding. Researchers at the South Dakota School of Mines & Technology are learning to manipulate the basic properties
of innovative materials to enable revolutionary new products.
“We’re really trying to enhance voxel-level
engineering,” says Travis Walker, Ph.D., assistant professor of chemical and
biological engineering at South Dakota Mines.
So, what’s a voxel? In photography, the
sharpness of an image depends on the number of pixels per inch. More pixels in
an image yield more vivid detail.
Move into three dimensions, and resolution is
not determined by pixels, but voxels. Like digital photography, the
resolution in 3D printing technology keeps getting better. Today, researchers are
working to manipulate single voxel sizes that are smaller than the diameter of a
human hair. This effort means very fine and detailed 3D printing.
The next evolution in 3D printing may involve
the ability to change the properties of a material, voxel by voxel. Just as many
different colored pixels make up a vivid photograph, many different types of voxels
can make a unique material.
“A large part of my research group is investigating
novel materials through controlling the presence of fillers inside additive
manufacturing on the voxel level,” says Walker.
As engineers gain the ability to change the makeup
of individual pieces of the puzzle, they can construct complex materials with
unique properties that have never been seen before.
“We study the fundamental physics on the voxel
level. Once we can control the properties of each voxel, we can make meta
materials, such as gradient materials, that can advance a number of materials
that you can find today,” says Walker.
Walker specializes in the study of fluid
mechanics. This work includes an effort to understand complex fluids, soft
solids, miscible fluid interactions, and biological systems. Everyone has a
basic understanding for how water flows, but thicker fluids like ketchup or
paint can exhibit different properties. Walker notes that these thicker fluids,
“can be a hindrance when trying to get ketchup out of a glass bottle, or it can
be a benefit when spreading paint on a vertical wall. These everyday examples
illustrate that complex fluids can be difficult to process, yet when exploited,
their complexity can also be useful.”
Part of Walker’s research, which is funded in
part by an NSF CAREER Grant, involves the use of tiny disks that can be
inserted into each voxel and then moved into a unique orientation using
magnetic fields. This work could have a range of applications, including more
efficient antennas for better wi-fi that enables the internet of things.
Significant challenges are ahead in these
fields of research. “We’ve been making composite materials like fiberglass for over
a century, but controlling things on the voxel level is much harder,” says
Walker. “The ability to do 3D printing exists, and the ability to insert
different particles into each voxel exists. Now, we need the right collaborators who have
a need for this kind of engineering application.”
The effort to overcome the challenges is
worthy, as research on the physics that happens at these tiny scales could have
broad implications, from new electronics to advances in medicine, pharmaceuticals,
and energy production. “When you attempt to engineer materials on the
sub-micron level -- how is the organization happening; how do things transport
thorough the microstructure -- the physics are the same across many different
materials,” says Walker.
Walker is helping to organize a technology
exchange on the advanced manufacturing that is now underway in the region. Black
Hills TEAM (Technology Exchange for Advanced Manufacturing) is planned for
July 13, 2020, on the campus of South Dakota Mines.