Abstract—This paper proposes a wireless patient monitoring system which integrates Bluetooth and WiFi wireless technologies. A wireless portable multi-parameter device was designated to acquire physiological signals and transmit them to a local server via Bluetooth wireless technology. Four kinds of monitor units were designed to communicate via the WiFi wireless technology, including a local monitor unit, a control center, mobile devices (personal digital assistant; PDA), and a web page. The use of various monitor units is intending to meet different medical requirements for different medical personnel. This system was demonstrated to promote the mobility and flexibility for both the patients and the medical personnel, which further improves the quality of health care.

Keywords—Physiological monitoring system; Wireless; Bluetooth; WiFi.

I. INTRODUCTION

With the increase of senior population in the human society, continuous health monitoring becomes progressively more important in the health care facilities. The medical personnel need to monitor the patient’s status in case of an emergency but would not desire to increase the number of room visits. As a result, there is a demand of a physiological monitoring system which enables the medical personnel to monitor the patient’s status remotely and accurately.

The fast development of wireless technologies and the increases in communication bandwidth facilitate the developments of e-health and telemedical systems [1]. Wireless and portable patient monitoring systems not only increase the mobility of patients and medical personnel but also improve the quality of health care [2]. In the developments of remote patient monitoring systems, many researchers have focused on transmitting physiological signals via the wireless local area network (WLAN) technology [3] and the Bluetooth wireless technology [4]. Some researchers have used the personal digital assistant (PDA) to acquire and transmit physiological signals from patient’s room to the central management unit in the hospital using the wireless technologies [3, 4].

Bluetooth wireless technology is an open specification that enables low-power and short-range wireless connections. WLAN technology is also known as WiFi wireless technology, which is a progressive open specification that enables longer-range connections. Few, if any, attempts have been made to integrate the wireless local area network (WiFi)

technology and the Bluetooth wireless technology to telemonitor patients continuously. In this paper, we propose a wireless patient monitoring system which integrates the WiFi wireless technology and the Bluetooth wireless technology. Through the portable Bluetooth wireless physiological signal acquisition device, patients can move freely in the room and the medical personnel can monitor the patient’s health status remotely through the control center, the mobile device or the web page via the WiFi wireless technology. In the consequence, the physiological monitoring system becomes more efficient and mobile.

II. METHODOLOGY

A. System Overview

The objective of this study is to design and implement a wireless physiological monitoring system for monitoring vital signs remotely to promote the mobility of both the patients and the medical personnel. Fig. 1 shows the architecture of the proposed system. The proposed system consists mainly of two parts: 1) the mobile unit, which is set up on the patient’s side to acquire the patient’s physiological signals, and 2) the monitor units, which enable the medical personnel to monitor the patient’s status remotely.

The mobile unit has several requirements that should be followed: 1) it should be portable and lightweight; 2) it should be able to acquire multi-physiological signals; 3) it should support wireless communication, which enables patients active freely.

Fig. 1. Architecture of the proposed system

A Wireless Physiological Signal Monitoring System with Integrated Bluetooth and WiFi Technologies

Sung-Nien Yu and Jen-Chieh Cheng Department of Electrical Engineering, National Chung Cheng University, Taiwan, R.O.C.

Proceedings of the 2005 IEEEEngineering in Medicine and Biology 27th Annual ConferenceShanghai, China, September 1-4, 2005

0-7803-8740-6/05/$20.00 ©2005 IEEE. 2203

Several monitor units are designated in the proposed system to meet the medical personnel different clinical requirements. These units include a local monitor unit, a control center monitor, a web page monitor, and several mobile device monitor units. With the wireless transmission capacity of the mobile units, the medical personnel can monitor the patient’s physiological signals and access the patient’s file from different monitor units. The monitor units have several requirements that should be followed: 1) it should be convenient for the medical personnel to access; 2) it should be able to monitor the physiological parameters and waveforms of the remote patients; 3) a database may be needed to integrate with certain monitor units to save the patients’ signals and files.

B. Mobile Unit

The main function of the mobile unit is to acquire the vital-sign signals and allow the patient to move around in the room. The signals acquired include a one-lead ECG and a breath signal. Fig. 2 shows the diagram of the mobile unit. First, the acquired signals are passed through instrumentation pre-amplifiers and filter circuits in the biomedical signal processing block. 0.5-50Hz band-pass filters are used to filter out the power-line noise to achieve better SNR ratio. Then through the amplifiers and the analog-to-digital converters (ADCs), the signals can be amplified with a total gain of 1000 and digitized to 8-bit data.

An AT89C51 microprocessor (Atmel Co., LTD., San Jose CA., USA) was embedded in the circuit and a tiny operating system (OS) was developed to control the peripheral circuits and the transmission of the digitized data [5]. Fig. 3 shows the architecture of the tiny OS, in which three interrupt services and three routine tasks were programmed to operate the mobile unit. When operating in a specific interrupt service routine (ISR), the corresponding flag is set up. The scheduler checks the flags of the tasks and decides which task to execute if more than one interrupts occur at the same time.

The digitized vital-sign signals are transmitted to the local monitor unit using a Bluetooth dongle (Chander Electronics Co., LTD., Taipei, Taiwan). This dongle supports the serial port (UART) profile [6]. The max data rate is 720 Kbps and the operation rage is within 10 meters. Fig. 4 depicts the physical circuit of the mobile unit.

C. Monitor Units

The monitor units consist of several kinds of applications, including 1) the local monitor application, 2) the mobile device monitor application, 3) the control center monitor application, and 4) the web page monitor application. Fig. 5 shows the architecture of the monitor units in the proposed system.

The local monitor unit is located in the patient’s room, which enables the doctor to monitor the patient’s health status during the room visits and transmits the signals to the control center via the WiFi network. The control center unit is

Fig. 2. Diagram of the mobile unit.

Fig. 3. Architecture of the tiny OS.

Fig. 4. Picture of the mobile unit.

Fig. 5. Architecture of the monitor units.

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situated at the nurse’s station, which allows the medical personnel to monitor the patient’s health status remotely and the patient’s information, such as vital-sign signals, personal information, and doctor’s diagnosis.

The mobile device monitor application is built on a personal digital assistant (PDA). With this unit, the medical personnel can monitor the patient’s health status right away. Through the web page, doctors can monitor the patient’s status and check records with any regular web page browser. These two monitor units increase the mobility and flexibility for the medical personnel to monitor the patient’s status at almost anywhere once they can connect to network services.

III. RESULTS

A prototype of the proposed system architecture has been developed. Efforts have been contributed to the development of user-friendly graphical user interfaces.

The local monitor unit serves the data bridging function between the mobile unit and the other monitor units. The local monitor unit receives and displays the vital-sign signals form the mobile unit via the Bluetooth network and then transmits them to the other remote monitoring units. Fig. 6 shows the user interface of the local monitor unit. The waveforms of the ECG and breathing signal are shown on the screen. Also shown are the patient’s information, heart rate, breath rate, and local time.

The control center is built on an IBM compatible personal computer. The software and the user interface are programmed by Visual Basic 6.0 on Windows XP platform. An MS-MDB database is integrated with the software program to manage the waveform data and the patients’ clinical records. Fig. 7 shows the user interface of the control center. The same waveforms and information are transmitted from the local monitor unit and displayed on the screen. In addition to its monitoring function, the control center provides the ability to archive and retrieve old records from the database through the graphical user interface.

The mobile device is built up with a personal digital assistant (PDA) (CASSIOPEIA E-200, Casio Computer Co., LTD., Tokyo, Japan). The user interface is programmed by Embedded Visual Basic 3.0 on a Pocket PC 2002 platform. Fig. 8 shows the front-panel of the mobile device. Due to the limitation of the screen size of the mobile device, we program the buttons to toggle the display of different vital-sign signals such that only one waveform is displays at one time. Moreover, the waveforms are displayed on the longitudinal direction of the screen in order to have better resolution.

In the web page monitor application, the user interface is programmed by ActiveX documents that can be accessed with regular web page browsers. When the medical personnel connects to the control center server via either regular LAN or WiFi network, the web page browser, such as Internet Explore (IE), can download and execute the ActiveX controls automatically

Fig. 6. The user interface of the local monitor unit.

Fig. 7. The user interface of the control center.

Fig. 8. The picture of the mobile device.

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automatically and produce the web page for telemonitoring the patient’s status. Fig. 9 shows the user interface of the web page, which is similar to what can be observed on the local monitor unit. The web page monitor application fulfills the need to monitor the patients’ status and records at any place where an internet service is accessible. In the consequence, it extends the range of this monitoring system to almost anywhere, although network delays may be inevitable.

IV. DISCUSSION

In this paper, a prototype of a wireless physiological signal monitoring system using Bluetooth and WiFi technologies has been proposed. For a wireless physiological monitoring system, there are some points that should be addressed and discussed.

A. Mobility

With the proposed system architecture, the patients are allowed to move freely in the room and the physiological signals can be acquire and transmitted through the portable Bluetooth wireless device. This system also provides the medical personnel the mobile device monitor units to telemonitor the patients’ statuses through WiFi network. Therefore, with the combination of Bluetooth and WiFi networks, the proposed system highly promotes the mobility for both the patients and the medical personnel.

B. Flexibility

The physiological monitoring system provides different monitor units for different clinical purposes. This system architecture increases the flexibility of this system. Moreover, this system based on the WiFi network and Bluetooth network is highly flexible and can be easily connected. Besides, according to the fast development of wireless technologies and the increasing communication bandwidth, we can expect that more wireless services will be provided and can be readily incorporated into the telemedicine services in the future.

C. Usability

The proposed system is designated with user-friendly interfaces. Both the mobile unit and the monitor units provide easy-to-use user-interfaces, which facilitate the usability of this system and reduce the need of a long-time-training before usage.

V. CONCLUSION

In this paper, a novel wireless physiological monitoring system was proposed and implemented. This system integrates the WiFi wireless technology and the Bluetooth wireless technology to effectively monitor the patients’ statuses remotely. A portable physiological signal acquisition device was developed which acquires vital-signals from the

Fig. 9. The user interface of the web page.

patient and transmit the data through Bluetooth wireless technology. Several monitor units were designated on different platforms to meet different clinical needs in monitoring and archiving patients’ records. With the combination of WiFi and Bluetooth wireless technologies and the development of different monitor units, this system highly improves the mobility, flexibility, and usability of the wireless physiological signal monitoring system.

ACKNOWLEDGMENT

This study was supported in part by the grant NSC92-2622-E-194-016-CC3 from the National Science Council, Taiwan, R.O.C.

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