Researchers 3D print tiny multicolor microstructures
Automatic approach could enable precision fabrication of optical
components and multimaterial structures

Date:
September 17, 2020
Source:
The Optical Society
Summary:
Researchers have developed an automated 3D printing method that can
produce multicolor 3D microstructures using different materials. The
new method could be used to make a variety of optical components
including optical sensors and light-driven actuators as well as
multimaterial structures for applications such as soft robotics
and medical applications.



FULL STORY ========================================================================== Researchers have developed an automated 3D printing method that can
produce multicolor 3D microstructures using different materials. The
new method could be used to make a variety of optical components
including optical sensors and light-driven actuators as well as
multimaterial structures for applications such as soft robotics and
medical applications.


========================================================================== "Combining multiple kinds of materials can be used to create a function
that cannot be realized with a single material," said research team
leader Shoji Maruo from Yokohama National University in Japan. "Methods
like ours that allow single-step fabrication of multimaterial structures eliminates assembling processes, allowing the production of devices with
high precision and low cost." In The Optical Society (OSA) journal
Optical Materials Express, Maruo and colleagues describe their new 3D
printing method and demonstrate it by creating various multicolor 3D structures. Their technique is based on stereolithography, a 3D printing
method that is ideal for making microdevices because it uses a tightly
focused laser beam to make intricately detailed features.

"The ability to make multimaterial microscale optical elements using
3D printing could aid in the miniaturization of optical devices used
for medical treatments and diagnoses," said Maruo. "This could improve
the ability to use these devices in or on the body while also enabling
them to be disposable, which would help provide an advanced and safe
medical diagnosis." Optimizing color stereolithography Stereolithography builds up a high-precision 3D structure by using a laser to harden light-activated materials known as photocurable resins in a layer by
layer fashion. Microfluidics are often used to hold the liquid resins,
but it is challenging to keep the different resins from contaminating
each other when switching materials without creating large amounts of
waste or forming air bubbles in the printed object.

In the new work, the researchers developed a way to hold the various
materials in a droplet state, which allows them to be more easily
exchanged in a closed space such as a microchannel without creating
waste. To suppress air bubbles, the 3D-printed structure is moved around
inside the resin each time a resin is replaced. They also integrated a
two-step process for cleaning the 3D printed structure when the resins
are changed to completely prevent cross- contamination.

To implement this optimized approach, the researchers created a palette
to hold multiple resins and placed it, two cleaning tanks and an air blow nozzle on a motorized stage. "All the processes, including 3D printing,
resin replacement, bubble removal and cleaning are sequentially carried
out using software we developed," said Maruo. "This allows multicolor
3D microstructures to be created automatically." Creating multicolor
3D structures The researchers tested the approach by placing various
types of photocurable resins in a palette and using them to create 3D microstructures. For one of these demonstration structures, a tiny
multicolor cube just 1.5 millimeters across, the 3D printing system
exchanged five colors of resin 250 times during a 6-hour fabrication
process. The researchers also showed that adjusting the number of layers
of multicolor resins made it possible to adjust absorbance of each part
of the structure, allowing them to create microstructures with colors
such as black by combining layers of red, blue, green and yellow.

"This method can be applied not only to multicolor resins but also to
a wider variety of materials," said Maruo. "For example, mixing various
ceramic micro- or nanoparticles with a photocurable resin can be used to
3D print various types of glass. It could also be used with biocompatible ceramic materials to create scaffolds for regenerating bones and teeth."
The researchers are now working to shorten the time required for processes
such as resin replacement and bubble removal to allow for even faster fabrication.

They also plan to use technology they previously demonstrated to build
a multiscale fabrication system in which the fabrication resolution can
be changed from less than a micrometer to several tens of micrometers
by modifying the focusing lens and laser exposure conditions.


========================================================================== Story Source: Materials provided by The_Optical_Society. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Taiki Maruyama, Hotaka Hirata, Taichi Furukawa, Shoji Maruo. Multi-
material microstereolithography using a palette with multicolor
photocurable resins. Optical Materials Express, 2020; 10 (10):
2522 DOI: 10.1364/OME.401810 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200917084100.htm

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