Electrical and Computer Engineering. NASA Research Partnership/MITAC. Virginia Commonwealth University. Virginia Commonwealth University. Richmond ...
VMote: A Wearable Wireless Health Monitoring System E. Hughes, M Masilela, P. Eddings Electrical and Computer Engineering Virginia Commonwealth University Richmond, VA USA
A. Rafiq, C. Boanca, R. Merrell NASA Research Partnership/MITAC Virginia Commonwealth University Richmond, VA USA
eahughesgvcu.edu
arafiqgvcu.edu
sports and/or weight management purposes. Bodymedia [1] has developed an armband, which uses multiple sensors for
Abstract - A low-power, wireless, wearable physiological monitoring system has been developed and implemented using commercial off-the-shelf components. The non-invasive system supports physiological monitoring of skin temperature, oxygen saturation (SpO2), heart rate (HR), blood volumetric pressure (BVP) and galvanic skin resistance (GSR). The sensors are integrated into a wearable device that can be used to monitor the health and wellness of various patient populations. Data
data acquisition over a fixed period of several days at a time. This data can then be downloaded to a PC and "lifestyle
information" such as energy expenditure, amount of physical activity, etc., can be extracted. The data is analyzed offline and at a later time. Similarly, Holter monitors are used in the
medical domain for data acquisition with offline data analysis processes.
collected by the sensors are sent wirelessly to a personal computer.
Martin et al [6] describe a wearable computer consisting of an ECG sensor attached to a patient with real time data which is fed back to the patient. Similar projects include [3,5,10]. Foster-Miller's [2] health monitoring garment for soldiers uses a health monitoring device attached to the soldier's garment and data is then transported using a Body Area Network (BAN) or Personal Area Network (PAN). Other systems with integrated technology on garments include work by Paradiso [9], where he describes a method of obtaining continuous ECG data from embedded sensors. Jovanov et al [4,6,8] provide a means of data acquisition from motion sensors. Oliver et al [7] present HEALTH health oaSatpoe monitoring technology a wearable real-time GEAR, tha prvdsdt.i leot
I. INTRODUCTION Wireless networking capabilities are changing the mechanisms for patient management. As tele-homecare and telemedicine become more prevalent, the technologies and systems that facilitate the communication of patient medical information also increase in importance. A low-power, wireless, wearable physiological monitoring system (VMote) has been developed and implemented using commercial offthe-shelf components. The system is well-suited for both tele-homecare and telemedicine applications. The targeted application for this study iS a small self contained system that uses multiple sensors in combination with wireless networks for physiological data monitoring of various populations. The prototype is a wireless device that consists of three commercial off-the-shelf sensors: a galvanic skin resister, a skin temperature sensor and a pulse oximeter. The continuous monitoring of patient physiological trends by medical staff can provide a venue for consistent clinical management prior to complications. A review ofrelevant recent work is included in Section 2. Section 3 gives an overview of the system specification details. Communication issues are discussed in Section 4 while results and conclusions are contained in Section 5.
observation of the above methodologies is that data is acquired from a single subject, not multiple networked subjects. The proposed Vmote system will facilitate data .. . acquisition from multiple networked subjects. 1. SYSTEM SPECIFICATION AND CAPABILITIES common
The VMote is non-invasive and supports physiological monitoring of skin temperature, oxygen saturation, heart rate, blood volumetric pressure, and galvanic skin resistance. In addition to these sensors, current research efforts include the integration of a core body temperature sensor and a respiratory analysis CO2 sensor. The sensors are integrated into a Crossbow Radio/Processor Module (mote) by way of a custom data acquisition prototype board. The current system provides critical readings in real time and is a work in progress.
II. PREVIOUS WORK In recent years there has been an appreciable rise in the production of commercial health monitoring systems for
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V. VMOTE APPLICATIONS AND FUTURE The VMote transmits at 900 MHz with a maximum data CONSIDERATIONS rate of 38.4 kbps and a transmission distance of up to 260 ft. The transmission distance is a function of a number of Main contributions of the VMote system include: a distance from the parameters that include..antenna type, .. . ' . . ..............means to analyze data online, as compared to other offline ground and the surrounding environment. Packaged as a data analysis systems; the capability of acquiring and wearable non-invasive system in the form of a cap, the interpreting data from both analog and digital devices thus VMote ensures ease of use as it is easy to don on and off. making the system compatible with analog and digital sensors; the capability of processing large amounts of data A. The Sensors which directly relates to the integration of more physiological sensors and variables; and the ability to The pulse oximeter measures the amount of oxygen in support multiple, networked users thus allowing the the patient's blood, heart rate, and Plethysmograph values. healthcare provider access to a group of patients instead of The galvanic skin resistor (GSR) measures the conductance data from a single individual. of the skin, and the temperature sensor measures the temperature of the skin. Both the GSR and the skin temperature sensors measure resistance (ohms) that is Additional areas of application include the monitoring of converted into voltage via an on-board analog to digital athlete physiological conditions, sleep pattern research and converter (ADC). healthcare for residents of rural or remote areas. The VMote could be used in the aerospace industry to monitor vital signs of astronauts. Similarly, it could be used to remotely monitor B. Hardware the elderly as well as members of the disabled population. A UART interface (via an Atmel Atmegal28 Due to the sensitive nature of medical information, microcontroller integrated onto Crossbow's Mica2 mote) is various data encryption techniques are currently being used to transmit data read from the sensors of the VMote. investigated. Other future considerations include enabling Customized radio/processor modules identical in functionality to the Mica2 mote are currently under preventive alerts that forecast medical events as opposed to development. They will eventually replace the Crossbow just monitoring them. mote giving way to a fully customized VMote. The REFERENCES customized VMote will be fully ZigBee compliant. Also, [1] BodyMedia. Bodybugg. http:// www.bodymedia.com. lower power microcontrollers are being considered as alternatives to the Atmel Atmegal28 microcontrollers [2] Foster-Miller. http://www_.osterrn11ercor. [3] T. Gao, D. Greenspan, M. Welsh, R. R. Juang, A. Alm, "Vital signs currently in use along with Atmel radio transceivers. monitoring and patient tracking over a wireless network," in
IV.
COMMUNICATION, INFoRmATo
Proceedings of the 27th Int'l Conf IEEE EMBS, Shanghai, pp. 1-5,
IV. COMMUNICATIONNTRANSPORTATION RNPRATION
AND ANALYSIS
[4]
Other research efforts have focused on personal digital assistant (PDA) or cell phone based communication technologies. We approach the information relay problem
body area network of intelligent motion sensors for computer assisted
physical rehabilitation. Journal of Neuroengineering and Rehabilitation, 22:6, 2005.
[5] D. Malan, T.Fulford- Jones, M.Welsh, and S.Moulton. Codeblue: An ad-hoc sensor network infrastructure for emergency medical care. In Proc. Int. Workshop on Wearable and Implantable Body Sensor Networks, 2004. [6] T. Martin., E. Jovanov, and D. Raskovic. Issues in wearable computing for medical monitoring applications: A case study of a wearable ECG monitoring device. In Proc. Intl. Symp. Wearable Computers (ISWC'00), pages 43-49, 2000.
from a different perspective. The VMote system uses the
wireless sensor's transceiver to communicate over a radio link with a base station node attached to a computer. At the base station, the information is passed to the computer for further processing and analysis.
Software has been
developed to visually display patient data on the computer for further analysis by a physician or caregiver. Multiple patients can be monitored and tracked by the base station, allowing for multiple patients in a single location to be
[7] N. Oliver, and F. Flores - Mangas. HealthGear: A real-time wearable and analyzing physiological signals. [8] C. Otto, A. Milenkovic, C. Sanders, and E. Jovanov, "System architecture of a wireless body area sensor network for ubiquitous health monitoring," Journal of Mobile Multimedia, vol. 2, pp. 307-
monitored by the system. Current tests include determining the maximum Local Patient Network (LPN) size. the mobility of of the existing wireless wireless Due toDuetheto mobility the patients, existing sensor networking schemes are not well suited for our Local Patient Network. Instead a novel ad-hoc network management and routing protocol to ensure communication reliability has been developed. In cases where there is signal attenuation, repeater wireless sensors can be used to boost
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[9] R. Paradiso. Wearable health care system for vital signs monitoring. In Proc. IEEE Int. Conf Information Technology Applications in Biomedicine, pages 283-286, 2003. [10] V. Shnayder, B. Chen, K. Lorincz, T. Fulford-Jones, and M. Welsh,
"Sensor networks for medical care," Technical Report TR-08-05,
and relay the signal.
Division of Engineering and Applied Sciences, Harvard University,
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Shanghai, Sep 2005. E. Jovanov, A.Milenkovic,C.Otto, and P.C. de Groen. A wireless
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