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2 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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Proposed Research



Low Cost Wireless Fetal Heart Rate Monitor by Using ZigBee technology

Keywords: Doppler ultrasound, Arduino Microcontroller, ZigBee Wireless Communication.

Introduction

In the United States,

the antepartum and intrapartum

evaluation of fetal status by using
fetal heart rate monitoring has been utilized for over 40 year
. It continues to be the most
commonly use
d technique that serves approximately 4.2 million women during labor and
delivery
1
. The current external fetal heart rate monitoring
machine used in hospital such as
continues electronic fetal monitor (EFM) requires mother to lie down in bed for a period of

time
depends on the condition of the mother. This may cause discomfort of
the mother.
Furthermore,
pregnancy

check
-
ups are required on monthly base
s. The abnormal fetus
activities may not obtained right away by the physician. As a result, scientists have been
focused on developing wireless fetal heart rate monitor that can be used at home during
women
pregnancy

and have the ability to continuously up
date the fetal status
2
.
Currently,
there are several
hand
-
held ultrasound fetal heart rate monitors based on Doppler effect are
commercially available. However, this type of fetal monitor may easily loss fetal heart rate
because of a maternal or fetal movement and
requires a recording cable to transfer data from
fetal monitor to the computer.

The objective of my research is to develop a real time wireless
feta heart rate monitor that can continuously obtain data, evaluate the fetal status on the
computer and send in
formation

to the physician if necessary
.

Research Plan

The main idea of the fetal monitoring is to ensure the fetus has the proper supply of
oxygenated blood. However, the direct measurement of oxygen saturation

during pregnancy is
impossible
3
. The abnormal activities can be represented through the analysis of fetal heart rate.
In this research the Doppler ultrasound technique will be used to
acquire fetal signals non
-
invasively.
The developing fetal probe will able to transmit a

pulse of
ultrasound
wave
with a
desire frequency of 2 or 3MHz.
A higher

frequency

will result a higher penetration depth but
not necessarily have a higher chance of fi
nding fetal heart beat
4
. Th
e ultrasound wave

penetrates the maternal and fetal body
and is reflected back from the internal body structures.
The frequency of the returned signal from a contracted organ such as fetal heart is shifted
in
accordance with Doppler effect
3
.
The time at which the
returned signal

is received depends on
a depth of the reflecting object. The received signal is

then

demodulated to
obtain the Do
ppler
frequencies. After getting the demodulated signal, a band
-
pass filter is required to separate
useful signal from interferences which usually caused by maternal
blood flow and fetal
movement. Then the signal will be processed
and displayed on
computer

to show the
results.

The main controlling unit of this

developing model is based on A
rduino microcontroller

for
generating ultrasound frequency, signal filtering and data processing.

Another

important part of this design is able to transfer data wirelessly
by
using ZigBee

technology
.


The advantage of using ZigBee to provide wireless sensor network is because it is
generally inexpensive and require relatively low power
5
.
The model will allow physician

to
obtain fetus activity without the presence of the pregnant mother. It will also allow the update
of the data processing algorism wirelessly in case of failure.
The Zigbee
-
Arduino fetal heart rate
monitor system is very useful in field operation because

it allow data to be sent to laptop or
mobile phone for data processing which free
up some required personnel to help other

patient
s
and increase the efficiency of monitoring.
The design of the ZigBee wireless algorism will be
separated into 3 parts: joini
ng the network, receiving the data from the probe and sending the
data.

I started this research by follow the engineering design pattern that I have learned from
my past research experience on text based visual prostheses. I concluded some of the past
obst
acles I have faced when design
ed

the hardw
are and tried to solve the problem before
starting to build the model. The knowledge I gained from writing an algorism for real time ECG
signal compression would greatly help me to reduce the amount of time I need to spend on
write the algorism for this mo
del.

Even though this Arduino
-
ZigBee fetal heart rate monitor system has several advantages
over traditional wired
electronic fetal monitor

and hand
-
held Doppler ultrasound device
, there
are still some uncertainties. For example, the possibility of getti
ng
false
-
positive results, t
he
security problem may occur when sending wireless information via internet.





References:



1

Chez, B. F. & Baird, S. M. Electronic fetal heart rate monitoring: where are we now?
The Journal
of perinatal &
neonatal nursing

25
, 180
-
192; quiz 193
-
184, doi:10.1097/JPN.0b013e31821643c6
(2011).

2

Jezewski, J., Roj, D., Wrobel, J. & Horoba, K. A novel technique for fetal heart rate estimation
from Doppler ultrasound signal.
Biomedical Engineering Online

10
, 92
-
92
(2011).

3

Jezewski, J., Roj, D., Wrobel, J. & Horoba, K. A novel technique for fetal heart rate estimation
from Doppler ultrasound signal.
Biomedical engineering online

10
, 92 (2011).

4

Ortiz, M. R.

et al.

in
Computers in Cardiology, 2005.

675
-
678.

5

Motika, G. & Prusty, A. in
Emerging Applications of Information Technology (EAIT), 2011 Second
International Conference on.

83
-
86.