DEVELOPMENT OF EMERGENCY MONITORING SYSTEM

FOR ELDERLY WHO LIVE ALONE

Dong Ik Shin, Pil June Pak

Dept. of Biomedical Engineering, Asan Medical Center, Seoul, Korea

Ji Hoon Song

SooEe Electronics Co., SeongNam, Korea

Se Kyeong Joo, Soo Jin Huh

Dept. of Biomedical Engineering, University of Ulsan College of Medicine, Ulsan, South Korea

Keywords: Emergency monitoring, Vital sign, Pulse Oxymetry, Elderly, Accelerometer.

Abstract: In this paper, we introduce a mobile device for the monitoring of the elderly vital signs. Using this mobile

device, we composed the emergency monitoring system. There are so many vital signs to monitor, but we

simplified vital signs as activity and heart rate. We measured the activity using 3-axis accelerometer and

measured the heart rate using pulse oxymeter. The major problem of pulse oxymeter is motion artifact. But

we suggested a new method using the combination of these two sensors. In case of active motion, we used and

analyzed the accelerometer signal and withdraw the pulse oxymeter signal. In case of no activity, we adopt

pulse oxymeter signal which has no motion artifacts. The important thing is to categorize activity patterns

such as normal or abnormal activity. When the device detects abnormal condition, it sends a short message to

server and then connected to the u-Healthcare center or emergency center.

1 INTRODUCTION

Nowadays u-healthcare already be a trend of these

years with IT/BT technologies. And, another point of

view, we must focus on the single elderly who must

be cared in terms of activity and vital signs of them.

This is very important social problem to solve.

According to the statistics Korea, the aging index

increasing fast in annual. So, there are needs of

emergency monitoring for single elderly. Transition

to aging society becomes very important problem day

by day. Especially for the single elderly, it is critical

problem that whose vital situation. According to the

data from Statistics Korea, the aging index will

increase rapidly from 9.5%(2006) to 14.3%(2018)

and 20.8%(2026). With this trend, the number of

single aged person is increases too.

The emergency monitoring system will be the

solution of these problems so we started this

development. So we proposed a monitoring system

that alarming the emergent status of the elderly who

live alone in their home. They will use compact

mobile devices to monitor their vital signals such as

SpO2 from PPG sensor and activities from

accelerometer.

And the second, the mobile device which gets vital

signals have features of small size and energy

efficiency.

2 SYSTEM OVERVIEW

2.1 Emergency Monitoring System

Fig. 1 shows the overall system diagram of

emergency system. The device module acquires vital

signs from several sensors and sends data to local

monitoring site or SMS server using local wireless

network and cellular network appropriately. And the

SMS server decides the situation and send short

message to the emergency center and/or to a family

member of single elderly. After this stage, the

operation will depend on Emergency center or

hospital.

179

Shin D., Pak P., Song J., Joo S. and Huh S..

DEVELOPMENT OF EMERGENCY MONITORING SYSTEM FOR ELDERLY WHO LIVE ALONE .

DOI: 10.5220/0003151601790183

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2011), pages 179-183

ISBN: 978-989-8425-37-9

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

Figure 1: Overall system diagram of Emergency

monitoring system.

2.2 Device Module

A device module may be attached to an ankle or wrist.

The key points are size/weight and battery life. We

apply several sensors to this device module which are

acceleration, touch, temperature, heart rate and SpO

sensors.

Fig. 2 shows a block diagram of our device module.

The microcontroller controls the major function of

the device, and optional functions such as GPS,

ZigBee, serial communication and CDMA. At this

time, we use our own protocol for wireless

communication between the device and base station

for tests. Accelerometer for sensing activities,

temperature sensor and touch sensor are located

inside the device. PPG sensor for pulse oximetry is

connected via serial port.

Figure 2: A block diagram of the device module.

Table 1 describes the specification of the device

module. Specifications have several terms. Small size,

light weight, various communication tools and

acquire various vital signals such as SpO2, activity,

body temperature and touch sensor for wearing

detection. Current consumption is maximum 180mA

to minimum 15mA at standby state. We use the

lithium-polymer battery that has 1200mA capacity.

And we prepared GPS function optionally.

Table 1: The Device Module Specification.

Term Specification

Size mm

(W x H x t)

45 x 90 x 15

Weight

96g(with battery, without CDMA module)

Communication ZigBee, CDMA IS-95A,95B, 2.4GHz RF, RS-232

Vital

Signals

SpO

breath, heart rate, blood O

saturation

Activity

3-axis accelerometer, Max.Range ±8g, 50Hz ISP

comm.

Body Temp. 0.2℃ I2 Ccommunication

Sensing Touch sensor for wearing detection

Current consumption 180mA(MAX) 15mA(waiting)

Battery Litium polymer 3.7V/1200mAh, 80 hours waiting

Charge 3.7V TTA standard cahrger

GPS 2dRMS 10m or lower

Data Transfer Rate 9,600bps(Max. 38,400bps)

Number of connections Normal: 1 time/20min, Emergency: 1 time/10sec

Fig. 3, 4 shows the internal algorithm of our device

module. When power is ‘ON’, the status of each

sensor is checked and stored.

Figure 3: The internal operation algorithm of device

module.

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The device module is composed of three sensors

which are body temperature, accelerometer and PPG

sensor. There is no ECG sensor, instead we will

derive the heart rate using PPG.



Figure 4: The internal algorithm of device module.

2.3 System Operation

The mobile device acquires vital signals. And the

mobile device optionally pre-processes the raw data.

Then, the mobile device sends data to Server. The

server post-process and decide the final state. If the

state is decided to emergent, the server send short

message to the emergency center and a family

member of single elderly.

When the device module detects an abnormal

status, it sends data to the message server using

wireless network. The message server finally decides

the situation and if emergent case the server send a

short message to the emergency center and family.

Table II shows an example of message format. It

contains a header, name, address, symptoms and

event time.

Table 2: Short Message from message server to emergency

center.

contents header

name

(age)

address Symtom1 Symptom2 time rsv

Byte 6 10 32 9 9 9 5

message [EM]

Hong

(72)

388-1,

PunaNap-dong

Increase

Temp.

23:15:37

HH:MM:SS

RSV

3 RESULT

We made a prototype of the device module. Fig. 5

shows our prototype. It shows a main module and

optional module for GPS and Bluetooth function.

Figure 5: A prototype of the device module.

Fig. 6 shows the wearing photograph. The ankle is

just a case of possible position. With the test, we can

wear on wrist or waist.

Figure 6: Wearing on ankle.

We tested the function of out device module in

laboratory and Fig. 7 shows the recorded data of light

walking.

We have tested in several situations. While

DEVELOPMENT OF EMERGENCY MONITORING SYSTEM FOR ELDERLY WHO LIVE ALONE

181

wearing on the forearm, the first three data show

activities from accelerometer. The fourth is SpO2

from PPG sensor. The fifth is heart rate but not

available yet.

Figure 7: Data from the device module when light walking.

Figure 8: Waveforms of various situations; (a) Standing.

Fig. 9 shows waveforms according variable

situations. The feature extraction will be our further

works.

Fig. 10 shows a short message on the cellular

phone of emergency center or a member of family.

The message indicates ‘decreasing breath and no

motion, so emergent status’.

Figure 9: Feature extraction by variable situation; (a)

Forward falling, (b) Backward falling, (c) Left falling, (d)

Right falling.

Figure 10: Short message on cellular (Message says,

[Emergency] Name(Age)/ Address/ Lower Breath

rate/Reduce motion/Time )

4 DISCUSSION

We are developing the emergency monitoring system

and small device module which is wearable on wrist

or ankle. During 2 years development schedule, we

are going one year schedule. We produced a

prototype device module and built monitoring system.

There are several problems to solve. One is the

physical size and weight. It is very important because

the main users may be the aged persons. And the

battery life is another problem to solve. We are

investigating carefully the benefits between weight

and battery life of the device module.

Our ideas are focused on reliability and easy usage.

Single elderly falls danger at home than outside.

There are many persons outside to give help. So they

will be less danger than home. So we can concentrate

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182

our efforts on home area network. The other

important things are minimization of complexity and

simplifying situations. We may just alert to

emergency center and/or family member. Further

proper actions must depend on human being not on

devices.

Finally we can not pass over the economic

viewpoints. Cheaper, lighter, easier to using the

device should be considered. Maybe, the support of

government or welfare foundation will be helpful.

5 FUTURE WORKS

We are developing a cheaper, smaller PPG module as

a vital sign sensor. We need pre-processing algorithm

to extract several features. We also must solve the

problem wearing on where and should minimize the

energy consumption of sensor module. At the system

operation stage, post-processing is very important to

judge proper state of a person whether emergent or

not. And we should refine data communication

protocol and short messages. There still remain

problems to solve. Policy consideration must be

solved and individual privacy is another problem to

consider.

ACKNOWLEDGEMENTS

This project is performed with the support of ‘Small

and Medium Business Administration, Korea’

REFERENCES

Amr Amin Hafez et. al., Design of a low-power ZigBee

receiver front-end for wireless sensors, Micro

Electronics Journal.(in progress)

Giuseppe Anastasi, Marco Conti, Mario Di Francesco,

Andrea Passarell, Energy conservation in wireless

sensor networks: A survey, Ad Hoc Networks 7 (2009)

537-568

Mathieu Hautefeuille et. al., Miniaturized multi-MEMS

sensor development, Microelectronics Reliability 49

(2009) 621-626

P. Mendoza, P. Gonzalez, B. Villanueva, E. Haltiwanger, H.

Nazeran “A Web-based Vital Sign Telemonitor and

Recorder for Telemedicine Applications”, in

Proceedings of the 26th Annual International

Conference of the IEEE EMBS San Francisco, CA,

USA, September 1-5, 2004, pp. 2196-2199.

Aleksandar Milenkovic et. al., Wireless sensor networks

for personal health monitoring: Issues and an

implementation, Computer Communications 29, 2006,

pp. 2511-2533

David Evans et. al., Vital signs in hospital patients: a

systematic review, International Journal of Nursing

Studies 38, 2001, pp. 643-650

Hak Jong Lee et. al., Ubiquitous healthcare service using

Zigbee and mobile phone for elderly patients,

International Journal of Medical Informatics 78, 2009,

pp. 193-198

M. Palikonda et. al., Sensor grid applications in patient

monitoring, Future Generation Computer Systems 26,

2010, pp. 569-575

A. Marco et. al., Location-based services for elderly and

disabled people, Computer Communications 31, 2008,

pp. 1055-1066

Francis E. H. et. al, MEMS-Wear biomonitoring system for

remote vital signs monitoring, Journal of the Franklin

Institute 346 2009, pp. 531-542

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