Wheaton Journal of
Neuroscience
Senior Seminar Research
Issue 1, Spring 2016:
"Life 2.0: Blurring the Boundary Between our Tech and Ourselves"
R.L. Morris, Editor. Wheaton College, Norton Massachusetts.
Original artwork by Ashley Wang '16
Electronic Skin: Expanding Sensory
Capabilities
Jessica L. Bernaski
NEURO 400 / Neuroscience Senior Seminar
Final Research Paper
27 April 2016
Electronic Skin: Expanding Sensory Capabilities
Jessica L. Bernaski
Final Research Paper written for
Wheaton Journal of Neuroscience Senior Seminar Research
Neuro 400 / Neuroscience Senior Seminar
Wheaton College, Norton Massachusetts
27 April 2016
Introduction:
Skin is the largest sensory organ of the body. Acting as a flexible apparatus that provides
both a protective barrier against the outside world and sensory information, human skin exhibits
many varied functions. Intentions to create a synthetic form of skin that mimics the natural
capabilities of human skin has resulted in the development of many different forms of artificial
skin (Hammock et al., 2013). One such form is electronic skin. This form of artificial skin
utilizes circuitry in combination with a flexible medium, which will produce comparable sensory
information to what is produced by natural human skin. Looking to the future, advancements in
this field of technology aim to not only reproduce the skin’s sensory abilities, but also to enhance
them.
Biology of Human Skin:
Replicating the capabilities of human skin in the form of artificial skin has proven to be
an immense challenge. Development of artificial skin is important because skin can be severely
damaged, meaning that some individuals do not possess functioning skin. This can pose serious
problems because human skin is integral in protecting the body against trauma, ultraviolet (UV)
radiation, temperature extremes, toxins, and bacteria (Amirlak & Shahabi, 2015). It also provides
tactile and thermal information to the brain through electrical impulses transmitted along
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neurons. Information about the external environment is carried along sensory neurons from the
peripheral nervous system (PNS) to the brain. Electronic skin aims to mimic the capabilities of
sensory neurons to provide sensory information. Sensory neurons, or "pseudounipolar” neurons,
are somewhat unique in that they have one axon that projects to the central nervous system
(CNS) and another that projects to the PNS, with their cell body being located in either the dorsal
root ganglion or one of the sensory ganglia of the sensory cranial nerves (Swenson, 2006). This
configuration allows both afferent (incoming) and efferent (outgoing) signals to be transmitted
between the CNS and PNS creating a feedback loop for sensation.
Electronic Skin in Prosthetics:
Electronic skin aims to mimic the sensory capabilities and flexibility of human skin. It
was originally developed for use in robotics, to provide feedback information on the pressure of
a robot’s grip when picking up objects (Ma, 2011). Current models of electronic skin have been
surpassing the capabilities of biological skin in terms of sensitivity, spatial resolution, and
elasticity due to advances in technology (Chortos & Bao, 2014). Advances in technology have
produced sensor arrays that can surpass the sensing capabilities of human skin, which can then
be utilized in electronic skin. A specific example of electronic skin that is in development is a
product called WiseSkin (Farserotu et al., 2015). WiseSkin uses innovative technology that can
transmit sensory information wirelessly from the apparatus applied over a prosthetic. Kim et al.
(2014) have also developed an ultrathin single crystalline silicon nanoribbon (SiNR) material
that is a promising candidate for artificial skin on prosthetics.
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Figure 1: Electronic skin configuration. This figure shows a multi-layer configuration for
electronic skin that contains sensor arrays as well as a heater to increase flexibility of the
material during stretching and compression. Figure adapted from “Stretchable silicon nanoribbon
electronics for skin prosthesis” (Kim et al., 2014).
This material uses strain, pressure, and temperature sensor arrays that are arranged in a
multi-layer configuration, as seen in Figure 1, to provide tactile and thermal feedback. The top
layer of this artificial skin contains humidity sensor arrays. The SiNR material works in
conjunction with a heat source, which can also be observed in Figure 1, in the base layer that
helps to keep the artificial skin flexible during stretching and contracting. Kim et al. (2014) aim
to make their SiNR artificial skin as similar to human skin as possible and propose that its use in
prosthetics could provide amputees with the ability to regain some sense of external stimuli.
Neurobiology/Technology Hybrid System:
Electrical impulses from sensory neurons that accurately convey sensory information are
what electronic skin aims to mimic in the use of prosthetics. One basic sense that is important to
the function of electronic skin is the ability to perceive pressure under normal (perpendicular)
compression and shear force, or parallel sliding across the skin (Rowe & Mamishev, 2004).
From pressure sensing, temperature and humidity sensors were added to create a more complete
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sensory profile that then could be directly connected to the nervous system. Connecting points on
the electronic skin array to corresponding points in the PNS is very important to providing
correct sensory feedback from the electronic skin. Inflammatory response and formation of scar
tissue must be avoided so that the connection between circuitry and the nervous system can
continue to function. Healing capabilities of the skin are also important. Tee et al. have
developed a self-healing composite that can be used at room temperature and is capable of
healing itself repeatedly (2012).
Predictions for the Future:
In the future, electronic skin will likely be a viable option to provide amputees with
sensation that they had previously lost. Electronic skin may be used in skin graft applications or
to expand the senses humans already possess (Chortos & Bao, 2014). Development of self
healing electronic skin is also in the future of this technology, narrowing the gap between this
artificial medium and its biological counterpart (Benight et al., 2013). Self-healing models of
skin in the future would help to cement that electric skin could be permanently applied in skin
grafts and could also mean that if the electronic skin were damaged, it would have the capability
to heal itself rather than having to be replaced. Technology developed for use in electronic skin
could be used in other fields, such as in mobile health and fitness tracking (Luo et al., 2014).
Advancements in fitness tracking could lead to more accurate health management and may help
to improve public health.
I have abided by the Wheaton Honor Code in this work.
Jessica L. Bernaski
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References:
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Benight, S. J., Wang, C., Tok, J. B. H., & Bao, Z. (2013). Stretchable and self-healing polymers
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