Better material for wearable biosensors

Date:
September 16, 2020
Source:
Binghamton University
Summary:
Researchers have used electrospinning to make porous silicone that
allows sweat to evaporate.



FULL STORY ========================================================================== Biosensors that are wearable on human skin or safely used inside
the body are increasingly prevalent for both medical applications
and everyday health monitoring. Finding the right materials to bind
the sensors together and adhere them to surfaces is also an important
part of making this technology better. A recent study from Binghamton University, State University of New York offers one possible solution, especially for skin applications.


========================================================================== Matthew S. Brown, a fourth-year PhD student with Assistant Professor
Ahyeon Koh's lab in the Department of Biomedical Engineering, served as
the lead author for "Electronic?ECM: A Permeable Microporous Elastomer
for an Advanced Bio-Integrated Continuous Sensing Platform," published
in the journal Advanced Materials Technology.

The study utilizes polydimethylsiloxane (PDMS), a silicone material
popular for use in biosensors because of its biocompatibility and soft mechanics. It's generally utilized as a solid film, nonporous material,
which can lead to problems in sensor breathability and sweat evaporation.

"In athletic monitoring, if you have a device on your skin, sweat can
build up under that device," Brown said. "That can cause inflammation
and also inaccuracies in continuous monitoring applications.

"For instance, one experiment with electrocardiogram (ECG) analysis
showed that the porous PDMS allowed for the evaporation of sweat during exercise, capable of maintaining a high-resolution signal. The nonporous
PDMS did not provide the ability for the sweat to readily evaporate,
leading to a lower signal resolution after exercise.

The team created a porous PDMS material through electrospinning, a
production method that makes nanofibers through the use of electric force.



========================================================================== During mechanical testing, the researchers found that this new
material acted like the collagen and elastic fibers of the human
epidermis. The material was also capable of acting as a dry adhesive
for the electronics to strongly laminate on the skin, for adhesive-free monitoring. Biocompatibility and viability testing also showed better
results after seven days of use, compared to the nonporous PDMS film.

"You can use this in a wide variety of applications where you need
fluids to passively transfer through the material -- such as sweat --
to readily evaporate through the device," Brown said.

Because the material's permeable structure is capable of biofluid, small- molecule and gas diffusion, it can be integrated with soft biological
tissue such as skin, neural and cardiac tissue with reduced inflammation
at the application site.

Among the applications that Brown sees are electronics for healing
long-term, chronic wounds; breathable electronics for oxygen and carbon
dioxide respiratory monitoring; devices that integrate human cells within implantable electronic devices; and real-time, in-vitro chemical and
biological monitoring.

Koh -- whose recent projects include sweat-assisted battery power and biomonitoring -- described the porous PDMS study as "a cornerstone of
my research." "My lab is very interested in developing a biointegrated
sensing system beyond wearable electronics," she said. "At the moment, technologies have advanced to develop durable and flexible devices over
the past 10 years. But we always want to go even further, to create
sensors that can be used in more nonvisible systems that aren't just on
the skin.

"Koh also sees the possibilities for this porous PDMS material in another
line of research she is pursuing with Associate Professor Seokheun Choi
from the Department of Electrical and Computer Engineering. She and
Choi are combining their strengths to create stretchable papers for soft bioelectronics, enabling us to monitor physiological statuses.


========================================================================== Story Source: Materials provided by Binghamton_University. Original
written by Chris Kocher.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Matthew S. Brown, Melissa Mendoza, Poorya Chavoshnejad, Mir
Jalil Razavi,
Gretchen J. Mahler, Ahyeon Koh. Electronic‐ECM: A Permeable
Microporous Elastomer for an Advanced Bio‐Integrated
Continuous Sensing Platform. Advanced Materials Technologies,
2020; 5 (7): 2000242 DOI: 10.1002/admt.202000242 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200916090528.htm

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