SENSORDEVICES 2014 : The Fifth International Conference on Sensor Device Technologies and Applications

Development of a Vital Signs Monitoring System Using Radio Frequency
Communication
Fábio Ferreira, Vítor Carvalho
School of Technology
Polytechnic Institute of Cávado and Ave (IPCA)
Barcelos, Portugal
vcarvalho@ipca.pt

Abstract—In this paper, the data transmission of anacquisition system for biomedical vital signs via Radio
Frequency (RF) communication is explored. It wasdeveloped a platform capable of recording the patient´sphysiological signals to check if any medical
evolution/change occurred. The system allows alsoacquiring the environment data, as for example theroom temperature and luminosity where the patient is.
The main achievement of this paper is the patients’ realtime health condition monitoring by the medical
personnel or caregivers that will contribute to prevent
health problems.
Keywords—ambient asssisted living (ALL); radio
frequency (RF); medical care terminal (MCT)I.

INTRODUCTION

This work is part of a research and development
project in Ambient Assisted Living (AAL) topic.
Continuous monitoring of biomedical signals is
crucial in diagnosis and clinical monitoring ofpatients. Nowadays, several biomedical signals areanalyzed. The health assistant needs to haveinformation of the patient's vital signs in order to bepermanently informed about the patient heath status[1][2]. However, this procedure is not easy toaccomplish. Regarding the acquisition of biomedical
signals various sensors are placed on the patient
including a series of cables to connect the sensors,which could be invasive and uncomfortable for thepatient and his/her mobility [3]. At this moment, thecommercial cost associated to the remote monitoringof biomedical variables in bedridden systems is
expensive and unaffordable for most of families [4].
An example of a Medical Care Terminal (MCT) fromBioPlux can be observed in Figure 1 [4].

Filomena Soares, José Machado, Filipe Pereira, Vítor
Carvalho
Algoritmi Research Centre, CT2M (2nd author)
University of Minho
Guimarães, Portugal
BioPlux clinical biofeedback software Graphical
User Interface (GUI) is used in muscle rehabilitation
allowing a more efficient medical intervention as well
as a faster patient recovery. It is a web-based
application, supported also by mobile operatingsystems.
The main objective of this work is thedevelopment of an electronic system using wirelesstransmission capable of registering the patient's vital
signs. Moreover, this project gives also the possibility
to the health aide to access the database of the patient,including the medical records and personal
information. This project is a first step in order toachieve a minimum invasive biomedical dataacquisition system, as it is further expected tointegrate the sensors in the patients’ clothes and/or inother common daily life tools.
This paper is organized as follows: Section IIpresents the biomedical sensors principle of operation
used in the project; Section III presents the developedsystem, Section IV presents some results. Section Vpresents the conclusion and future perspectives ofwork.
II. BIOMEDICAL SENSORSIn this section, we describe some of the biomedical
sensors used in this project.
A. Electrocardiogram (ECG)
During the electrical activation of themyocardium, the heart is swept by a "front activation"
whose meaning and direction are modified in fractionsof a second. The ECG detects the electrical activity ofthe heart, reflecting its activity, Figure 2 [5].

Figure 2. Electrocardiogram wave [5]Figure 1. Bioplux clinical biofeedback software GUI [4]Copyright (c) IARIA, 2014.

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SENSORDEVICES 2014 : The Fifth International Conference on Sensor Device Technologies and Applications

B. Body Temperature Sensor
The junction of two metals generates atemperature difference. The principle of operation of
the temperature sensor is based on this process(thermocouple). Two materials of two different types
are attached; the potential difference is measured
between two points. Through this potential difference,
it is possible to obtain the temperature. Figure 3 shows
an example of the structure of the temperature sensor(thermocouple) used [6].

Figure 5. Block diagram of the program

Figure 3. Thermocouple [6]C. Airflow Sensor
The airflow is obtained by heating a wire by anelectric current. The resistance of the wire increases as
the temperature of the wire increases as a consequenceof the airflow variation. Thus, it is possible to measure
the airflow through the amount of current passing
through the wire; see Figure 4 [7].

A. System Hardware
The system hardware is based on the Arduino
platform, including an Atmel microcontroller AVR[8]. The programming languages used are C and C++.
Figure 6 presents an example of the connection
between the room luminosity sensor, i.e., Light
Dependent Resistor (LDR), the Arduino and the Radio
Frequency (RF) module.

Figure 4. Airflow sensor [7]Apart from these sensors, other sensors are
considered in the project as the oximeter, the galvanic
skin response, the patient position and the glucometer.
III. SYSTEM DEVELOPED
Figure 5 presents the overall block diagram of thesystem developed. This system registers the patient´sphysiological signs; it allows the medical personnel toaccess the patient´s personal information and medicalcondition, as well as the applied treatment. Moreover,it also allows the remote access to monitor thepatient's condition.
The database can store the data of the patient,
medical personnel, health aid and health unit.

Copyright (c) IARIA, 2014.

ISBN: 978-1-61208-375-9

Figure 6. Room luminosity sensor (LDR) physical connection

The sensor (Figure 6) is plugged into the Arduino
Analogue to Digital Converter (ADC) input (with aresolution of 12 bits [9]). After reading the sensor, thevalue is transmitted via the Arduino serial port (RX,TX) to the XBee and then to the acquisition system.
This procedure is also used for the other systemsensors.
B. Developed Database
The software used for data modeling was theMicrosoft Access [10]. Figure 7 shows the developed
database for data storage considering seven maintables plus one auxiliary table.

100SENSORDEVICES 2014 : The Fifth International Conference on Sensor Device Technologies and Applications

Figure 9 shows an example of the interface
developed to register the light present in the patient’sroom [12].

Figure 9. Light sensor LabVIEW interface [12]Figure 7. Data modeling

The developed database records the dataassociated to the patient (tables Patient, Report,Sensors and Readings), the data associated to the
medicalpersonalresponsible(tablesResponsible_nurse and Responsible_doctor) as well as
the data associated to the health unit (tableHealth_unit).
C. LabVIEW Interface
Figure 8 shows an example of the user interface
developed in LabVIEW to consult information about apatient [11]. The database is accessed via a Universal
Data Link (UDL) connection. UDL was created tostore connections with databases. The serial port
establishes the connection between LabVIEW andXbee. A time period is defined for each sensor
reading. The value is stored in the database along withthe date and time when the acquisition was performed.

Apart from the light intensity in the patient’sroom, the system also registers the air carbon
monoxide level, the air alcohol level and the room
temperature.
IV. EXPERIMENTAL RESULTS
In this section, three examples of the experimental
results are presented, namely the temperaturemonitoring of the patient room, the access to thepatient´s data and also the patient´s body temperature.
A. Temperature Room Sensor
In the menu from Figure 10, the medical personnel
may choose to monitor the room temperature
throughout the day by selecting the overall time of theacquisition. By observing Figure 10, it is verified thatthe patient room temperature was around 30ºC during
the system measurement (one hour).

Figure 10. Room temperature monitoring

B. Medical Reports
As it is seen in Figure 11, the medical personnel
can select a time interval and list the patient reports.
To accomplish this, it has to insert the code of thepatient and click on the “Search” button.
Figure 8. LabVIEW user interface – patient database consult

Copyright (c) IARIA, 2014.

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SENSORDEVICES 2014 : The Fifth International Conference on Sensor Device Technologies and Applications

The conjunction of the biomedical sensors and theenvironmental sensors allows obtaining a very usefulprofile of the patients heath condition as well as theenvironment were he is exposed. The transmission ofthis information via RF allows a less invasive system
to the users (patients and caregivers).
V. CONCLUSION AND FURTHER WORK

Figure 11. Consult reports

C. Biomedical Sensors
The system was first tested with two healthypersons: a) 28 years old, female, measuring 1.73 mand weighting 62 kg; b) 31 years old, male, measuring
1.76 m and weighting 79 kg. The first test was carriedout to obtain the value of body temperature. Figure 12
refers to the sensor placement and Figure 13 shows
the user interface where the temperature is acquired
through wireless communication and registered in achart.

This paper described a system based on a medicalcare terminal using data transmission via RF. The
physiological and environment data are acquired. An
added value of this project is the real-time monitoring
allowing the medical personnel to observe the patient
healthcare condition at anytime and anywhere. All thedata in registered in a database, allowing the physician
to monitor the patient´s evolution over time.
So far, the system was tested in laboratory. In thenear future, we aim to integrate all the sensors and test
the system in clinical environment.
This work aims to develop a minimum invasive
vital signs data acquisition system including thebiomedical sensors either in the patients’ clothes
and/or in other common daily life tools.
ACKNOWLEDGMENT
This work has been supported by FCT – Fundaçãopara a Ciência e Tecnologia within the Project Scope:
PEst-OE/EEI/UI0319/2014.
REFERENCES[1]

Figure 12. Placement of the body temperature sensor in the patient[12]

Tianbing M. F. and Chuanzhi F., “Sensors state monitoring
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[2] Alonso S. V., “Autonomous optical system for themeasurement of biomedical parameters”, Catalunya:
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[3] Burns A. et al, “SHIMMERTM-A wireless sensor platform fornoninvasive biomedical research”, IEEE Sensors Journal,
Volume 10, Issue 9, Sept. 2010, pp.1527-1534.
[4] bioPLUX
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analogreadresolution,
http://arduino.cc/en/Reference/AnalogReadResolution(acessed in September 2014)[10] Microsoft Access, http://office.microsoft.com/en-us/access/(acessed in September 2014)[11] NI LabVIEW, http://www.ni.com/labview (acessed inSeptember 2014)[12] Pereira F., Carvalho V., Soares F., Machado J., Bezerra K.
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Mechanics, Optics & Mechatronics, 2013, no. 48, pp.138-14

Figure 13. Obtaining the body temperature profile in the MCT [12]Copyright (c) IARIA, 2014.

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