
286 Page 2 of 11 J Med Syst (2016) 40: 286
portable system for a long-term ECG signal detection with
low costs is highly desired.
Thanks to the development of mobile Internet and wire-
less sensor networks (WSNs) [28], wearable ECG monitor-
ing systems have emerged which are able to detect ECG
signals using a non-intrusive sensor and transmit the signal
to the smart phone through wireless transmission tech-
niques, such as Bluetooth or Zigbee [6, 7, 20, 24, 25]. For
the sake of portability, electrodes of the WSN-based ECG
monitoring systems are usually less than traditional meth-
ods. At the expense of accuracy, it is sufficient to collect
the basic information of the heart. These portable sensors
are usually embedded into some wearable textiles, which
have little impact on the user’s daily activities. With the
aid of these systems, long-term ECG can be monitored in
a cost-effective manner. However, to the best of our knowl-
edge, nearly all existing systems cannot work without a
smart phone, which is used as a receiver and processor of
the ECG data [8, 9]. Due to limited power and computa-
tional capabilities, the complex tasks of data transportation
and processing may have a great impact on the daily use of
the smart phone. Furthermore, in order to support all the OS
platforms of smart terminals, great efforts are required for
the cross-platform development of the mobile application.
In this paper, the architecture of an ECG monitoring sys-
tem based on the Internet-of-Things (IoT) cloud is firstly
proposed. Based on this architecture, we design and imple-
ment a wearable ECG monitoring system. The ECG data
gathered from the human body will be transmitted directly
to the IoT cloud using Wi-Fi without the need of a mobile
terminal. Compared with Bluetooth or Zigbee, Wi-Fi can
provide higher data rates and wider coverage areas. In order
to provide convenient and timely access to ECG data for
users, both the HTTP and MQTT servers are deployed in the
IoT cloud. The gathered data are stored in a non-relational
database, i.e., Redis, which can greatly improve the speed
and flexibility of data storage. A web-based graphical user
interface is implemented so that it provides ease of access
for doctors and patients alike using smart phones of differ-
ent OS platforms to access to the data services provided by
the IoT cloud. The proposed system has been successfully
deployed and fully tested with demonstrated effectiveness
and reliability in ECG monitoring.
The reminder of this paper is organized as follows.
Section “Architecture of IoT-based ECG Monitoring Sys-
tem” presents the architecture of the IoT-based ECG mon-
itoring system. The system implementation is introduced
in Section “Implementation of the IoT-based ECG Moni-
toring System”, which includes a monitoring node, the IoT
cloud and a graphic user interface (GUI). In Section “Expe-
rimental Results and Analysis”, we conduct several tests on
a healthy volunteer in order to verify the reliability of the
proposed system. Finally, Section “Conclusion” concludes
this paper.
Architecture of IoT-based ECG Monitoring System
The architecture of the IoT-based ECG monitoring system
is illustrated in Fig. 1, which mainly consists of three parts,
i.e., the ECG sensing network, IoT cloud, and GUI.
ECG Sensing Network
The ECG sensing network is the foundation of the entire
system, which is responsible for collecting physiological
data from the body surface and transmitting these data to
the IoT cloud through a wireless channel. Wearable ECG
sensors are usually adopted in this system, which have lit-
tle impact on the user’s daily life. Through this means,
ECG data can be recorded over long hours or even days.
Then, the ECG signals are processed through a series of
procedures, such as amplification, filtering, etc., to improve
the signal quality and to meet the requirements of wireless
transmission.
The ECG data gathered from sensors are transmitted to
the IoT cloud via a specific wireless protocol, e.g., Wi-Fi,
Bluetooth, Zigbee, etc [23]. All the three protocols can pro-
vide enough data rates for transmitting ECG signals with
satisfying energy consumption. However, due to the limited
communications ranges of Bluetooth and Zigbee, a smart
terminal (such as a mobile phone) is usually needed to
receive the ECG data and then send the data to the IoT cloud
through the wireless protocols of the General Packet Radio
Service (GPRS) or Long Term Evolution (LTE). Compar-
isons among various types of ECG sensing networks are
giveninTable1.
IoT Cloud
Thanks to the development of the advanced IoT techniques,
ECG data can be stored and analyzed effectively and effi-
ciently. With the aid of an IoT cloud, computation-intensive
data process and analysis tasks can be carried out in power-
ful servers, which greatly eases the burden of smart devices
[26]. Generally speaking, an IoT cloud for ECG monitor-
ing usually consists of four functional modules, i.e., data
cleaning, data storage, data analysis, and disease warning.
•
Data cleaning: Significant features can be extracted
from ECG signals so as to detect potential heart dis-
eases. However, during the processes of data collection
and transmission, noise may be introduced into the
ECG signal, which would adversely affect the diagnosis