Author: Yeh-Liang Hsu, Che-Chang Yang, Tzung-Cheng Tsai, Chih-Ming Cheng,
Chang-Huei Wu (2006-12-21); recommended: Yeh-Liang
Note: This paper is published in Telemedicine
and e-Health, Vol. 13, No.1, February, 2007, p. 69-78.
Development of a Decentralized Home
Telehealth Monitoring System
usefulness of home telehealth systems has been recognized, and all technologies
required are readily available, expectations for its widespread adoption have
not been realized. This paper presents the development of a Portable Telehomecare
Monitoring System (PTMS). What sets this work apart from most other systems is
the focus on a highly decentralized monitoring model and the portable nature of
the system. We believe that this is the approach that is needed to make such
systems economically viable and acceptable to the end-users.
The PTMS is a
decentralized system, in which a single household is the fundamental unit for sensing,
data transmission, data storage and analysis. It is not necessary to subscribe
service from a home health care provider, and the infrastructure required is
minimal, too. Equipped with different sensors, the PTMS can be used for
long-term personal health data management in a home environment. It can also be
easily implemented in a home environment at very low cost. Like the large-scale
home telehealth systems, the PTMS also provides care-givers with convenient
access to the health data and real-time event-driven messages in urgent
situations. Several PTMS applications are described in this paper, including environmental
monitoring, monitoring of activities of daily living, an RFID-based entrance
guard system, sleep quality monitoring, vital sign parameter monitoring, and a
Key words: home health monitoring, telehealth, e-health
countries are facing the problem of increasing number of elderly. In an aging
society, it is highly desirable to reduce the need for medical services by
maintaining the health of the population. The need of health care and
management for the elderly is an urgent issue.
Home has become
the centerpiece of health delivery system today. Intensive monitoring of health
parameters in the home environment is necessary for health care and management.
Telehomecare, or the more modern term home telehealth, can be defined as the
use of information and communication technologies to enable effective delivery
and management of health services at a patient’s residence . Home telehealth
differs from telemedicine in the sense that people who transmit and receive
medical information are not necessarily medical doctors but the patients
themselves and their families, nurses, care-givers, home-helpers and medical
technical experts, etc .
activities are underway in the development of home telehealth systems. By
reviewing 578 research papers published between 1990 and 2003, Koch gives an
overview about the current state and future trends in research on home
telehealth in an international perspective .
research, commercial systems are already available in Europe, North America and
Japan. For example, Japanese household electric appliance manufacturers such as
Panasonic, NEC, Fujitsu, and Sanyo all sell remote monitoring devices, and more
than 8,100 units have been in use . The largest share “Urara”, invented by
Nasa Corporation, has been adopted in Kamaishi
City in Japan. The device uses cable TV or
ISDN (Integrated Services Digital Network) for data transmission and is equipped
with memory, sphygmomanometer, electrocardiogram (ECG), electric signboard, and
a button for answering questions. Transmitted health data is checked by nurses
at the hospitals and are reported to the doctors, as well as its users .
Other terminals with similar functions are “MEDICOM” form Sanyo and “Sukoyaka
Mate” from NEC.
telehealth systems adopt the following sequence for vital sign parameter (VSP) monitoring:
sensing of various VSPs è sensing
data transmission è data
storage and analysis è
medical actions. Figure 1 shows a typical example of a home telehealth system.
Users use the terminals at home or public places to measure their VSPs, such as
blood pressure, heart rate, ECG, weight and body temperature, and the data are
sent to the home health care provider through the
Internet. Medical institutions can access the health data and take necessary
database is often used in this structure for data storage and analysis, and the
home health care provider partnering with a medical institution plays the major
role. Users subscribe to a service from the home healthcare provider, instead
of buying a hardware product. Telephone line and the Internet, which are
readily available in most homes, are commonly used for transmission of sensing data.
To mobilize the VSP measuring devices, wireless communication technologies have
been incorporated into the measuring devices.
Figure 1. A typical example of a home telehealth system
usefulness of the home telehealth systems has been recognized in many studies
[6, 7, 8], and all technologies required are readily available, expectations
for its widespread adoption have not been realized. In our observation in Taiwan, the initial
cost of such home telehealth service being too high, and this cost not covered
by medical health insurance seem to be the main reasons why home telehealth
systems are not well accepted. Moreover, whether the users have enough trust on
the home health care provider so that they are willing to transmit their
private health data to the home health care provider on a long term basis is
also an important concern. Finally, the route from the VSP sensor to the centralized
server in the home health care provider is very long. System stability and data
integrity are hard to maintain.
This paper describes the development of a
Portable Telehomecare Monitoring System (PTMS). The PTMS is a decentralized
system. Instead of using the centralized database structure that gathers data
from many households, a single household is the fundamental unit for sensing, data
transmission, storage and analysis in the PTMS. The monitoring data is stored
in the Distributed Data Server (DDS) inside a household. The DDS is a
microcontroller-based device which integrates the following four functions:
receiving sensor data, computation capability for preliminary data processing,
storage of monitoring data, and communication capabilities via Internet or using
the mobile phone short message. Instead of login the centralized database in a home
health care provider, authorized personnel directly access the DDS for
monitoring data of the household.
decentralized structure, the PTMS is a product-oriented system rather than a
service-oriented system. It is not necessary to subscribe service from a home health
care provider. The word “portable” means that all devices of the PTMS are
designed to be modular and portable, and the PTMS can be easily customized and
installed in a home environment. Equipped with different sensors, the PTMS can
be used for long-term personal health data management of the elderly in a home
environment. Like the large-scale systems using the centralized-database
structure, the PTMS also provides caregivers with convenient access to the
health data, and real-time event-driven messages in urgent situations. The PTMS
also has possible home security and smart house applications.
The rest of this
paper is organized as follows. Section 2 of this paper describes the structure
of the PTMS, and Section 3 presents the applications already developed based on
this structure. Section 4 describes an extension of the PTMS, the “Telepresence
Robot”. Finally, Section 5 outlines the possible future developments of PTMS.
The PTMS Structure and the
Distributed Data Server
Figure 2 shows
the structure of the PTMS. Sensing data from sensors embedded in the home
environment are transmitted to the DDS, which is the core component of the
PTMS. Sensing signals are then processed and stored in the DDS. Authorized remote
users can request data from the DDS using an Internet web browser (through an
application server) or a Visual Basic (VB) program (direct access to the DDS).
Event-driven messages (mobile phone short messages or emails) can be sent to
specified caregivers when an urgent situation is detected.
Figure 2. The structure of the PTMS
Figure 3 shows a
picture of the laboratory prototype of the DDS, which consists of a PIC server mounted
on a peripheral application board. The PIC server integrates a PIC
Microchip), EEPROM (24LC1025, Microchip) and a networking IC (RTL8019AS,
Realtek). It provides networking capability and can be used as a web server.
Most peripheral functions of the DDS are built on the application board. The peripheral
application board (as well as the program in the PIC microcontroller) can be
easily customized to adapt to different sensors and applications. The dimension
of the DDS prototype is 40mm×85mm×15mm.
serial interface (RS-232) are the primary communication interfaces of the DDS
with client PCs and other devices. The DDS also receives external signals
(e.g., sensor signals) through specific analogue or digital I/O ports, and
provides inter-integrated circuit (I2C) communications to allow
connections with external modules. In addition, a mobile phone short message service
module can be optionally connected to the DDS via I2C,
which makes it possible to send text messages from the DDS to specified
caregivers when an urgent situation is detected. The DDS can also be connected
to a wireless Local Area Network (LAN) card and becomes a wireless device
monitoring data are processed and stored in a Multi-Media Card (MMC) in FAT16 file
format. Remote users can request for historical monitoring data through a VB
application program or an Internet web browser. Further data analysis or
processing (such as authorization management, creating graphical displays and
tables) can be built in the VB application programs or in an application
server. Compared with using a PC as a home server, the DDS is low cost, has
smaller package, consumes lower energy (thus can be powered by batteries), is
not affected by virus, and is safer and more reliable.
Figure 3. Laboratory prototype of the DDS
several advantages of the PTMS structure over the traditional centralized
(1) The scale of the PTMS is much smaller. A single household can be a
running unit of the PTMS. It is not necessary to subscribe service from a home
health care provider. The infrastructure required is minimal, too. Thus the PTMS
can be easily adapted (customized) and implemented in a home environment at
very low cost.
(2) Instead of sending the health monitoring data to a centralized
database in a home health care provider, health monitoring data are stored
within the household. Only authorized caregivers can access the data. Privacy
is better protected.
(3) The route from the sensor to server is much shorter. Data transmission
is easier and more reliable, and communication bandwidth will not be occupied
by meaningless sensing data continuously transmitted from sensors to the
centralized database. When the Internet communication fails, the local system
can still function normally and keep collecting data. Thus data integrity is better
(4) This distributed structure can be adapted if a centralized database
is needed. As shown in Figure 2, instead of waiting passively for data, the
centralized database can actively request for data from DDSs in many households
in a batch mode.
describes the various PTMS applications that have been developed.
sensors such as temperature sensor and humidity sensor, the PTMS can perform environmental
monitoring, which is the most typical and fundamental application of the PTMS. Besides
home environmental monitoring, this system also finds application in
environmental monitoring of museums, libraries and exhibition halls. Figure 4
shows the VB interface developed for the National Palace Museum of Taiwan for
temperature and humidity monitoring. On the left side of the screen, real-time
data from temperature and humidity sensors mounted on four different DDSs can
be monitored simultaneously. The user can also download historical data by clicking
on the calendar on the top half of the screen, and perform analyses such as
calculating average temperature of the day, and plotting the temperature trend
of the week.
Figure 4. VB interface of environmental monitoring
Monitoring of Activities of
The term “activities
of daily living (ADL)” refers to a basic set of everyday activities or tasks,
such as bathing, eating, dressing or walking, that an individual should be able
to perform in order to live independently. An ADL monitoring system is
developed based on the PTMS structure. The purpose is to monitor the change in
pattern of daily physical activities, to recognize the transition of a senior
from a healthy, independent state into a state of incapacity and dependency,
and to remind the caregivers to take early actions. In this system, special-designed
sensors detect activities such as eating, bathing, using the toilet, lying in
bed and watching TV. All sensors are embedded in the home environment so that
the subjects may not be aware of the sensing actions taking place. Sensor
signals are transmitted to the DDS through a battery-powered RF transmitter.
Besides the sensors installed in the environment, a wearable sensor based on a tri-axial
accelerometer is now being developed to recognize postural movements of the
subjects when walking, sitting and standing or in postural transitions.
Caregivers can use an interface similar to Figure 4 to read real-time sensor
data, download historical data, perform various analyses, or set up event-driven
messages (mobile phone short messages or email messages) once any sensor is
Integrating RFID with PTMS
Figure 5 shows
the structure of a PTMS-based entrance guard system. Radio Frequency Identification
(RFID) readers combined with optical switches are used as the sensors in the
PTMS. The DDS is also connected to a mobile phone “Short message Module for
Data Transmission (SMDT in Figure 5)”. When a person with an RFID tag passes
through the entrance, the RFID receiver identifies the ID and sends it to the
DDS. Combined with the sensor signals from the optical switches, the DDS can also
identify whether the person is entering or leaving. This event is then logged in
the DDS. An email or a mobile phone short message is sent to the management
personnel if a specific event is detected. This system can be used for ADL
monitoring of the elderly at home, and it also finds applications in nursing
homes, hospitals and kindergartens.
Figure 5. Structure of an entrance guard system
Sleep Quality Monitoring System
percentage of the elderly has sleep problems. Figure 6 shows the structure of a
PTMS-based sleep quality monitoring system. Special-designed sensors are
connected to the DDS to evaluate sleep quality from the subject’s external behaviors
(body temperature, body movement, breath, and snoring). The sleep quality
sensors are designed in an unrestrained, non-conscious way, so that long-term
sleep quality monitoring can be performed in a home environment – on the
subject’s own bed. From the external behavior signals instead of vital signs
(e.g. brain waves), the algorithm built in the DDS can determine sleep quality
indices such as the time in bed, sleeping time, latent period, times of
Figure 6. The structure of a sleep quality
measuring devices can be integrated with the DDS for VSPs monitoring, including
body temperature, blood pressure, weight, glucose and ECG. Integration of an electronic
sphygmomanometer and a glucose monitor with DDS has been successfully demonstrated.
The data acquired from these two measuring devices can be transmitted to the DDS
through RS-232 serial interface for data processing, storage, and further
board of the DDS is also adapted to become an ECG Holter. ECG impulse signals
are sent to the DDS for signal processing, including amplification, DC-bias
isolation, A/D conversion and digital filtration. With built-in algorithm in
DDS, QRS wave, RR-internal, heart rate (sphygmus) can be calculated, and the
possible occurrence of arrhythmia can be predicted. ECG waveform and resulting
data can be displayed on a PC which DDS is connected to, or remote PC clients
through the Internet in real time. These data are also stored in the MMC using
the FAT16 file format, and can be later accessed by doctors through the
Internet for evaluation of cardiovascular diseases.
means visual, kinesthetic, tactile or other sensor feedback from the
teleoperator to the human operator that is sufficient and properly displayed
such that the human operator feels that he is present at the remote site, and
that the teleoperator is an extension of his own body . “Dr.Robot” developed
by InTouch Health Inc. is a good application example of a telepresence robot
. The doctor can drive this telepresence robot to patrol and check up on
associated with an increased risk for isolation. A telepresence robot (Figure 7)
is designed to provide a new way of communication and a possible tool for telehomecare
visit by a healthcare provider at his/her residence. Basically, the
telepresence robot is a “mobile DDS”, which integrates various sensors, a
network IP camera with audio module, a wireless LAN access point, actuators,
and batteries, altogether inside a vehicle. Users can control the movement of telepresence
robot from a remote client PC to move around. Two-way audio and one-way video
communication can be transmitted through the Internet. Any PTMS-related function
can be carried out as well.
robot also has the ability to perform fundamental autonomous behaviors when not
being controlled, such as following a given track, detecting obstacles, and
auto-charge at low-battery capacity.
Figure 7. Tele-presence robot
Discussion and Future Work
usefulness of home telehealth systems has been recognized in many studies, expectations
for its widespread adoption have not been realized. This paper presents an
on-going project of developing the PTMS, which aims to satisfy the needs for
efficient and individualized home telehealth systems with limited financial
resources. What sets this work apart from most other systems is the focus on a
highly distributed monitoring model (and the portable nature of the system)
together with a mobile robot. We believe that this is the approach that is
needed to make such systems economically viable and acceptable to the
end-users. The PTMS also provides a solution to the shift from provider-driven
home telehealth systems to user-centered home telehealth systems.
applications are demonstrated. A patent portfolio of the PTMS (Figure 8) is
constructed to provide a system level concept of the various applications of
the PTMS. Some of these applications have been tested in practical
environments, and are proven to be stable and reliable in collecting,
transmitting, and storing sensing data. The elderly people and their caregivers
are the main target users when this project was first initiated. Currently, the
environmental, ADL and the VSP monitoring systems are under long-term
evaluation by the users and caregivers in a nursing home for the elderly, and by
several selected elderly who live in their homes. The future work will focus on
the commercialization of the PTMS to provide a portable, low-cost,
user-centered tool for home telehealth.
Figure 8. Patens Portfolio of PTMS
This research is
supported by the National Science Council, Grant No. 94-2213-E-155-016. This
support is gratefully acknowledged.
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