Wireless ECG Monitor

forestevanescentElectronics - Devices

Nov 2, 2013 (4 years and 11 days ago)

117 views

ABSTRACT

Annually,

heart

disease

causes

over

17

million

deaths

worldwide
.

One

of

the

best

ways

of

getting

preventive

prognoses

is

to

use

electrocardiograms

(ECGs)
.

The

newest

trend

with

ECG

devices

has

been

to

increase

their

mobility,

which

allows

them

to

be

more

broadly

usable
.

A

critical

aspect

of

this

is

using

recent

advances

in

low
-
power

computing

and

wireless

transmission

to

create

a

small,

unobtrusive

device
.

With

such

a

device,

patients

can

maintain

their

regular

lifestyles

while

still

receiving

intermittent

monitoring

feedback
.

Such

a

device

would

also

be

useful

for

monitoring

the

progress

of

pacemakers

and

other

heart

implants

in

non
-
hospital

settings
.

One

of

the

shortcomings

of

current

devices

(
eg
.

Holter

monitors)

is

that

they

are

still

unwieldy

and

thus

interfere

with

patients'

activities
.



This

project

takes

the

first

step

towards

making

such

a

device

by

designing

and

implementing

a

low
-
cost

hardware

prototype

which

acquires,

digitizes,

and

wirelessly

transmits

a

simulated

ECG

signal

to

a

nearby

computer

acting

as

a

web

server
.

This

data

can

then

be

accessed

over

the

Internet

through

a

mobile

device
.


AUTHORS:


Willy Bernal EE ‘10

Rohit

Chandra EE ‘10

Jason
Delisser

EE ‘10

Eric Pinter EE ‘10


ADVISORS:

Dr.
Rahul

Mangharam

Special thanks to Ni Lei, Godwin Meyers
,
and
Matthew
Shieh



DEMO TIMES:

Thursday, April 22, 2010

9:00, 9:30 AM, 3:00, 3:30 PM


GROUP #3

FRONT
-
END ACQUISITION

ECG

signals

read

from

a

patient’s

body

have

small

amplitudes

and

are

very

noisy
.

Such

a

signal

is

unsuitable

for

digitization
.

The

original

analog

signal

must

be

filtered

and

amplified

to

yield

a

more

easily

interpreted

signal
.

The

front
-
end

acquisition

portion

of

the

circuit

amplifies

the

differential

signal

from

a

patient

before

putting

it

through

notch

and

low

pass

filters
.

These

filters

attenuate

ambient

noise

and

also

remove

high

frequency

components

which

are

irrelevant

for

ECG

analysis
.

This

filtered

analog

signal

is

then

digitized

using

the

AD
7718
,

a

24
-
bit

sigma
-
delta

ADC
.


WIRELESS COMMUNICATION

The

Firefly

Sensor

Networking

Platform

is

used

in

this

project

for

one

way

data

communication

between

the

device

and

a

computer
.

This

platform

uses

the

IEEE

802
.
15
.
4

standard

which

is

suited

for

wireless

personal

area

networks

implemented

using

embedded

devices
.

One

node

is

connected

to

the

device,

and

the

other

to

a

computer

which

receives

the

data
.

Data

transmission

rates

can

be

adjusted

depending

on

the

application
.

SMART PHONE DISPLAY

The

digitized

signal

is

transmitted

to

a

web

server

which

can

then

be

accessed

using

any

web

browser
.

This

signal

can

also

be

displayed

on

a

smart

phone

capable

of

Internet

access

(in

this

case

an

iPhone
)
.

The

application

on

the

iPhone

can

plot

the

transmitted

data

for

viewing

by

the

patient

or

a

medical

professional
.

It

also

has

an

emergency

button

which

calls

a

pre
-
programmed

medical

provider

or

professional
.

MICROCONTROLLER

This

circuit

uses

the

ATmega
1281

to

control

the

operation

of

the

main

components
.

Using

a

serial

peripheral

interface

(SPI),

the

microcontroller

communicates

with

and

synchronizes

the

ADC,

the

accelerometer,

the

MicroSD

memory

chip,

and

the

transceiver,

dividing

computing

time

between

all

of

them
.

It

runs

the

Nano
-
RK

real

time

operating

system

which

is

specially

developed

for

the

Firefly

Sensor

Networking

Platform
.

ECG ANALYSIS

Beat

rate

analysis

alone

is

sufficient

to

diagnose

certain

problems
.

Thus,

a

beat

rate

detector

was

developed

in

Matlab

to

process

the

digital

output

of

the

circuit
.

Eventually,

this

will

be

converted

to

C,

which

can

then

be

implemented

on

the

microcontroller

(considerably

reducing

the

amount

of

data

transmitted)
.

For

now,

it

is

a

standalone

application

which

takes

an

existing

ECG

waveform

and

calculates

the

effective

beat

rate
.

RESULTS

Wireless ECG Monitor

Front
-
End
Acquisition

Analog to
Digital
Converter

Microcontroller

Transmitting
Node

Receiving
Node and

Web Server

Smart
Phone
Application

Band
-
pass
Filter

Remove
Baseline
Drift

Differentiate

Square

Integrate

Thresholding

Peak
Detection

Beat Rate
Calculation