Medical Design Briefs - December 2021 - 26

Cheng and the team plan to
improve upon their prototype for
future applications, including addressing
how patients or clinicians may use
the sensor for incremental glucose
measurements or continuous monitoring
to determine treatment actions,
such as administering insulin. They
also intend to refine and expand this
platform for more comfortable monitoring
of other biomarkers that can be
found in the sweat or interstitial fluids
that fill the space between cells in the
body.
" We want to work with physicians
and other health care providers to see
how we can apply this technology for
daily monitoring of a patient, " Cheng
says. " This glucose sensor serves as a
foundational example to show that we
can improve the detection of bio -
markers in sweat at extremely low
concentrations. "
Other contributors include co-first
author Jia Zhu, co-first author
Shangbin Liu, Zhihui Hu, Xianzhe
Zhang, Ning Yi, Kairui Tang and
Michael Gregory Dexheimer, De -
partment of Engineering Science and
Mechanics; Qing Wang with the
Department of Materials Science and
Engineering in the College of Earth
and Mineral Sciences; Xiaojun Lian
and Jian Yang with the Department of
Biomedical Engineering; and Jennifer
Gray with the Materials Research
Institute.
Hu is also affiliated with the Wuhan
University of Technology in China,
and Yi is also affiliated with the Penn
State Department of Materials Science
and Engineering. Cheng is also affiliated
with the architectural engineering
and biomedical engineering departments
in the College of Engineering
and the Department of Materials
Science and Engineering in the Penn
State College of Earth and Mineral
Sciences, as well as the Engineering
Energy and Environ mental Institute,
Materials Research Institute, and the
Institute for Computational and Data
Sciences.
The National Science Foundation
and the National Heart, Lung and
Blood Institute of the National
Institutes of Health (award number
R61HL154215) supported this work.
This article was written by Gabrielle
Stewart, Penn State. For more information,
visit https://www.psu.edu. A video of the
technology is available at https://youtu.
be/23MpXrneNIM.
Optical Design Considerations for Additive Manufacturing
Light-based methods open
many opportunities for
medical applications.
Gray Optics
Portland, ME
Additive manufacturing (also known as
3D printing) has been around since the
early 1980s, with the first technologies
using ultra-violet sources as an opticsbased
approach to solidify polymer
resins. Over the decades, new technologies
have enabled creation of functional
parts using a wide variety of polymers,
powders and even metals. The use of 3D
printing has grown exponentially across
multiple industries, none more so than
medical, where multiple applications
have benefitted from the ability to rapidly
manufacture custom orthopedic im -
plants for knee and hip replacement surgeries.
Dentistry is one of the largest
adopters of 3D printing where it is used
to create highly tailored crowns, bridges,
and aligners found in orthodontics.
Light as a means of directed energy has
opened a myriad of opportunities of 3D
printing for medical applications, where
lasers, high-power LED sources and
projection optics are used to reliably create
high-resolution features at everincreasing
production rates. Initial
machine architectures leveraged available
off-the-shelf (OTS) optics and system
components that often required
26
Cov
Dichroic
(%T, 1050-1100nm)
Laser
Collimating
Optics
1
0.9
0.9
0.7
0.6
0.5
0.4
0.3
0.2
0.1
500
Dichnoic
Laser
Control
Optics
%R
500-700nm
Detection Range
Detection
Module
550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200
Wavelength (nm)
Powder Bed Chamber
(Build Plate)
Scan
Optics
Optical
Window
Fig. 1 - Optical path of a laser powder bed fusion (LBPF) 3D printer showing all core optics and
photonics product technologies used to control and direct the laser beam to the powder chamber
and detection pathway for real-time optical monitoring of the build. Inset shows the spectral profile
of the dichroic beam splitter optic used to direct light into the detection path. (Spectra courtesy of
Iridian Spectral Technologies)
some performance trade-offs. However,
more complex geometries with finer features
and demands on surface finish
required greater control of the energy
source along with the ability to monitor
and stabilize the process in-situ. Thus,
current and future generation machines
now employ highly customized optical
designs to efficiently and repeatably
direct light to the working plane.
Engineers face many advanced challenges
related to designing and selecting
the right optics (e.g., glass type, surface
shape, optical coatings, manufacturing
www.medicaldesignbriefs.com
ToC
tolerances), when constructing industrial
scale 3D printers that operate reliably
over build times that can extend from
hours to days. These machines often
must pass strict certification processes
and conform to regulatory standards of
medical implants. This article covers
many important technical topics for engineers
to consider, including:
* Maximizing light
laser to the powder bed.
* Optical components and their function
to enabling precision part manufacturing.
Medical
Design Briefs, December 2021
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from the
Transmisson Value

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Medical Design Briefs - December 2021

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