Sensors
and
Actuators
A
267
(2017)
532–537
Contents lists available at ScienceDirect
Sensors
and
Actuators
A:
Physical
journal homepage: www.elsevier.com/locate/sna
A
facile,
precise
radial
artery
pulse
sensor
based
on
stretchable
graphene-coated
fiber
Siyao
Zang,
Qi
Wang
∗
,
Qing
Mi,
Jinnan
Zhang,
Xiaomin
Ren
State
Key
Laboratory
of
Information
Photonics
and
Optical
Communications,
Beijing
University
of
Posts
and
Telecommunications,
Beijing
100876,
People’s
Republic
of
China
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
18
July
2017
Received
in
revised
form
15
October
2017
Accepted
19
October
2017
Available
online
26
October
2017
Keywords:
Pulse
sensor
Graphene-coated
fiber
Pulse
waveform
analysis
a
b
s
t
r
a
c
t
We
design
and
fabricate
a
facile,
portable
and
scalable
radial
artery
pulse
sensor,
then
successfully
employ
it
into
the
analysis
of
personalized
health
status.
The
sensing
component
comes
from
a
stretchable
graphene-coated
fiber
which
shows
good
linearity
and
sensitivity
to
the
tensile
strain.
Further
com-
bined
with
the
smart
structure
of
the
sensor,
the
precise
detection
of
periodic
pulse
wave
and
the
wave
changes
induced
by
exercise
and
disease
becomes
avaiable
and
repeatable.
In
particular,
the
obtained
single
waveform
contains
almost
all
the
characteristics
the
medical
analysis
requires,
from
which
we
can
evaluate
the
cardiovascular
risk
factors
for
citizen
medicine,
home
healthcare
and
disease
prevention.
©
2017
Elsevier
B.V.
All
rights
reserved.
1.
Introduction
Recently,
the
incidence
of
cardiovascular
disease
have
increased
quickly
and
showed
the
trend
of
rejuvenation
mainly
due
to
the
unhealthy
lifestyle
and
accelerating
pace
of
life
[1,2].
Aware
of
the
seriousness
and
potential
risk
of
this
issue,
people
pay
more
attention
to
their
health
status
and
eagerly
require
more
related
information
to
realize
personalized
healthcare.
In
order
to
satisfy
the
increasing
demands,
sensors
devised
to
capture
human
vital
signs
have
been
highly
valued
[3–5].
Many
investigations
have
already
shown
a
close
association
between
central
artery
wave
and
radial
artery
pulse
wave
[6–9].
In
particular,
through
radial
artery
pulse
wave,
researchers
can
get
some
key
physical
properties
of
elastic
arteries
(e.g.
aortic
pressure
and
augmentation
index)
and
then
accurately
evaluate
the
cardiovascular
risk
[10–12].
There-
fore,
the
precise
detection
of
radial
artery
pulse
wave
is
of
great
importance
and
also
attracts
much
interest.
Up
to
now,
the
existing
detection
systems
of
the
radial
artery
pulse
wave
are
mainly
based
on
ultrasonic
measurement
[13],
photoplethysmography
[14–16],
laser
triangulation,
[17]
and
pres-
sure
sensing
using
common
piezoelectric
[18]
or
magnetoelastic
materials
[19].
Most
of
them
strongly
rely
on
the
complex
system
structures
[9,13–19]
to
realize
the
precise
detection.
Furthermore,
the
poor
mechanical
compliance
of
conventional
sensing
elements
(e.g.
metal
foils
and
semiconductors)
adopted
in
those
systems
∗
Corresponding
author.
E-mail
address:
wangqi@bupt.edu.cn
(Q.
Wang).
limit
their
applications
in
wearable
sensing
[20].
The
emergence
of
flexible,
facile,
and
stretchable
strain
sensors
can
solve
the
above
problems
well
[21].
Nanomaterials
such
as
carbon
nanotubes
(CNTs)
[22],
graphene
[23–25]
and
metallic
nanowires
[26,27]
together
with
polymers
have
been
frequently
employed
to
fabri-
cate
such
sensors,
in
order
to
combine
the
superior
electrical
and
mechanical
properties
of
nanomaterials
with
the
flexibility
and
stretchability
of
polymers.
Encouragingly,
some
of
them
(sensors
fabricated
with
graphene
[24,25]
and
AuNWs
[26,27])
are
able
to
sense
the
wrist
pulse
signals,
however,
their
sensing
ability
to
the
pulse
signals
is
mainly
confined
to
count
wrist
pulse
rate
or
dis-
tinguish
the
rate
changes
over
a
period
of
duration,
which
is
very
similar
to
the
easily
available
smart
bracelet.
In
this
study,
we
designed
and
fabricated
a
facile,
portable
radial
artery
pulse
sensor
using
a
flexible
and
stretchable
graphene-
coated
fiber.
Owing
to
the
outstanding
electrical
property
of
reduced
graphene
oxide
(RGO)
as
well
as
the
flexible
support
from
the
fiber,
the
RGO-coated
fiber
presented
good
linearity
and
sen-
sitivity
to
the
tensile
strain,
which
enables
the
highly-effective
detection
of
the
pulse
wave.
Through
the
smart
structure,
the
radial
artery
pulse
sensor
is
capable
of
sensing
the
subtle
changes
of
the
pulse,
identifying
the
individual
discrepancy
and
detecting
almost
all
the
characteristics
needed
by
medical
analysis
to
determine
the
cardiovascular
risk
factors,
which
is
of
great
significance
to
citizen
medicine,
home
healthcare
and
disease
prevention.
Combined
with
https://doi.org/10.1016/j.sna.2017.10.058
0924-4247/©
2017
Elsevier
B.V.
All
rights
reserved.