Conference PaperPDF Available

Wearable Health Monitoring System using Flexible Materials Electrodes

Authors:

Abstract and Figures

Bio-signals including electrocardiogram (ECG), respiration rate, motion-related signals, plantar pressure distribution are important for monitoring and assessing a person's health status. Via some of the bio-signals, some diseases or abnormalities such as cardiovascular diseases or a human fall can be detected. However, the traditional health monitoring systems have limitations as they are expensive, not-easy-to-use, stationary, inconvenient and uncomfortable to use. It is required an advanced solution for dealing with the limitations while maintaining a high quality of services such as high-quality signals and accuracy. Therefore, we present a novel wireless wearable health monitoring system in this paper. The system consists of an upper limb device and a lower limb device using flexible materials such as polydimethylsiloxane-graphene compound and textile materials for collecting different ECG, EMG, respiration rate, motion-related signals, plantar pressure distribution. The complete system is implemented, tested and verified in a clinical environment in a hospital. The results show that the system can obtain high-quality bio-signals and can be a potential application for both home-care and hospital-care.
Content may be subject to copyright.
Wearable Health Monitoring System using Flexible
Materials Electrodes
Shenjie Bao 1,2, Tuan Nguyen Gia1, Wei Chen2, and Tomi Westerlund1
1Department of Future Technologies, University of Turku, Turku, Finland
2Center for Intelligent Medical Electronics, School of Information Science and Technology, Fudan University, China
Email: {shenjie.s.bao,tunggi,tovewe}@utu.fi, w chen@fudan.edu.cn
Abstract—Bio-signals including electrocardiogram (ECG), res-
piration rate, motion-related signals, plantar pressure distri-
bution are important for monitoring and assessing a person’s
health status. Via some of the bio-signals, some diseases or
abnormalities such as cardiovascular diseases or a human fall
can be detected. However, the traditional health monitoring
systems have limitations as they are expensive, not-easy-to-use,
stationary, inconvenient and uncomfortable to use. It is required
an advanced solution for dealing with the limitations while
maintaining a high quality of services such as high-quality signals
and accuracy. Therefore, we present a novel wireless wearable
health monitoring system in this paper. The system consists of
an upper limb device and a lower limb device using flexible
materials such as polydimethylsiloxane-graphene compound and
textile materials for collecting different ECG, EMG, respiration
rate, motion-related signals, plantar pressure distribution. The
complete system is implemented, tested and verified in a clinical
environment in a hospital. The results show that the system can
obtain high-quality bio-signals and can be a potential application
for both home-care and hospital-care.
Keywords— Bio-signal, Bio-potential, Acquisition, Wireless,
Portable, Wearable, IoT
I. INTRODUCTION
Bio-signals play an important role in monitoring and assess-
ing a person’s health status. For instance, electrocardiogram
(ECG), blood pressure, body temperature, and respiration rate
are the vital parameters [1]. By analyzing and extracting
important features from these bio-signals or parameters, some
diseases such as some of the cardiovascular diseases can be de-
tected [1]. At the hospital, these bio-signals are often acquired
by several devices which are often stationary and use many
wires (e.g., 3-channel or 12-channel ECG monitoring devices).
In some cases where a patient needs to be monitored in 24-72
hours, this can cause some skin damages, inconveniences, and
uncomfortability. For example, adhesive Ag/AgCl electrodes
used for collecting ECG may cause skin damage, especially
for a new-born child when it has been used for a long period of
time [2]. In addition, these devices cannot be properly utilized
for home-users due to their limitations such as expensiveness,
requirements of expert users and inconveniences. Wearable
devices that are small, light-weight and can be used for a long
period of time are a suitable solution for the limitations.
Many wearable devices for health monitoring have been
proposed but they still have limitations [1]. For instance, state-
of-the-art wearable ECG monitoring systems still rely on adhe-
sive Ag/AgCl electrodes [3]. In these systems, 50/60Hz noises
can be eliminated by filtering hardware or software but other
noises such as motion artifacts are not properly considered at
the device. Some of the wearable ECG monitoring systems
use textile electrodes but they cannot properly remove all
noises (e.g., due to movement artifacts and the heterogeneity of
the skin-electrode impedance) [4, 5]. Some other systems use
three-dimensional accelerometers or piezo-sensors but their
collected signals contain noises due to move artifacts and
other surrounding sources [6]. Many wearable devices cannot
both collect different bio-signals including ECG, respiration
rate, motion-related signals, electromyogram (EMG), plantar
pressure distribution simultaneously and overcome the limi-
tations. Therefore, this paper presents an advanced wireless
wearable e-health monitoring system including an upper limb
device and a lower limb device using flexible sensing materials
such as Polydimethylsiloxane-graphene (PDMS-graphene) and
stretching textile electrodes. The system is non-invasive and
comfortable to use for the users. The system is able to
eliminate noises from different sources such as surrounding
sources and movement artifacts, and then sends the high-
quality filtered signals via Bluetooth Low Energy (BLE). The
completed wearable system is designed and implemented.
Then, it is tested and validated in the clinical environment in
the hospital. It is noted that this paper is a summary of a master
thesis in which some results have already been published in
conferences and registered for a Chinese patent by S. Bao -
the main author of the master thesis [7, 8].
II. SY ST EM D ES IG N
The proposed devices are designed according to the analysis
and clinical findings after the interview with medical experts.
The upper limb device can collect ECG, respiration rate and
motion signals. The lower limb device can acquire EMG,
plantar pressure distribution and motion signals. The structure
of these devices is shown in Fig. 1a and Fig. 1b. The flexible
materials are compared and properly selected for ECG, EMG,
plantar pressure and respiration signal acquisition. Then, the
hardware and software parts are designed and the quality of
the collected signals is assessed and compared with the clinical
gold standards applied in the hospital.
The hardware system mainly contains three parts including
data acquisition, signal transformation, and signal processing.
The upper limb and lower limb devices use a similar platform
and peripheral components. These devices collect the signals
Fig. 1. Structure of upper limb and lower limb devices
from the upper limb and lower limb via different sensors.
Then, the micro-controller unit (MCU) processes and analyzed
the collected data with our software and algorithms.
In the upper limb device, textile electrodes and a PDMS-
graphene stretching sensor are used for ECG and respiration
signal acquisition correspondingly. The inertial measurement
unit (IMU) is used for collecting motion signals. The research
value of the upper limb is to discover and propose a systematic
way to evaluate the ECG signal collected by different kinds
of textile electrodes and the respiration signal collected by
the novel resistance-based stretching sensor. For the lower
limb device, carbonized foam electrodes are applied for the
EMG signal acquisition, which can reduce the power line
interference [9]. A novel high-accuracy array is used for the
plantar pressure distribution [7].
III. IMPLEMENTATION AND RES ULTS
The hardware systems were implemented based on the
design concept. In the upper limb device, STM32F405,
ADS1292, and MPU9250 were used as MCU, ECG sen-
sor, and IMU, correspondingly. The sampling frequency was
250Hz. A finite state machine (FSM) was designed to control
multi-tasks inside MCU and direct memory access (DMA) was
utilized to improve energy and latency efficiency. LabVIEW
was also designed with the function of real-time raw data
demonstration, heart rate and respiration rate calculation and
abnormal alert. The implementation of the lower limb device
was published in a conference [7]. The hardware cost of the
system is 50 US dollars in which the upper limb system costs
around 29 US dollars and the lower limb costs 21 US dollars.
PSG (Polysomnography) was used as the gold standard
to compare with the proposed upper limb device for the
respiration rate. The clinical experiments were conducted on
six infants. The mean age of the subjects was 29 days (median
31.5 days, standard deviation 14.1 days, range from 18 to 58
days). Three male and three female subjects were recruited.
The waveforms with the same respiration frequency structure
and pattern were obtained by the proposed system and PSG.
A total of 240 recorded one-minute data sets, 218 sets of data
were available for analysis. The remaining 22 sets were lost
due to the nurses’ medical procedures. The correlation analysis
results of 218 sets of data used by PSG and the proposed
system were shown in Fig. 2. The correlation coefficient was
Fig. 2. Results of correlation analysis using PSG and the proposed system
0.98, indicated that the proposed system and PSG had a strong
correlation in respiration rate monitoring.
IV. CONCLUSION AND FUTURE WOR K
This paper presented a wireless wearable system for health
monitoring. The system consisting of an upper limb device
and a lower limb device could collect the high quality of
bio-signals including ECG, EMG, respiration rate, motion-
related signals and plantar pressure distribution. In addition,
by using flexible materials such as PDMS-graphene and textile
materials for collecting the bio-signals, the system does not
damage a user’s skin while remaining comfortability and con-
venience. The results show that the system can be potentially
applied for IoT-based home-care and hospital-care systems. In
future work, more sensors for collecting other bio-signals such
as galvanic skin response (GSR) signal, peripheral capillary
oxygen saturation (SpO2), and continuous blood pressure will
be added into the systems. In addition, advanced algorithms
for the evaluation of users’ health status will be integrated into
the system.
REFERENCES
[1] R. M. Aileni et al., “Wearable electronics for elderly health monitoring
and active living,” in Ambient Assisted Living and Enhanced Living
Environments, pp. 247–269, Elsevier, 2017.
[2] J-Y. Baek et al., “Flexible polymeric dry electrodes for the long-term
monitoring of ecg,” Sensors and Actuators A: Physical, vol. 143, no. 2,
pp. 423–429, 2008.
[3] T. N. Gia et al., “Energy efficient fog-assisted iot system for monitoring
diabetic patients with cardiovascular disease,Future Generation Com-
puter Systems, vol. 93, pp. 198–211, 2019.
[4] L. Beckmann et al., “Characterization of textile electrodes and conductors
using standardized measurement setups,” Physiological measurement,
vol. 31, no. 2, p. 233, 2010.
[5] S. Ramasamy and A. Balan, “Wearable sensors for ecg measurement: A
review,” Sensor Review, vol. 38, no. 4, pp. 412–419, 2018.
[6] D. C. Mack et al., “Development and preliminary validation of heart rate
and breathing rate detection using a passive, ballistocardiography-based
sleep monitoring system,” IEEE Transactions on Information Technology
in Biomedicine, vol. 13, no. 1, pp. 111–120, 2008.
[7] S. Bao et al, “A wearable multimode system with soft sensors for lower
limb activity evaluation and rehabilitation,” in 2018 IEEE I2MTC, pp. 1–
6, IEEE, 2018.
[8] H. Chen et al., “A wearable daily respiration monitoring system using
pdms-graphene compound tensile sensor for adult,” in 2019 41st IEEE
EMBC, pp. 1269–1273, IEEE, 2019.
[9] H. Chen et al., “Characterization of a novel carbonized foam electrode for
wearable bio-potential recording,” in 2018 IEEE 15th BSN, pp. 173–176,
IEEE, 2018.
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Blood glucose plays an important role in maintaining body's activities. For example, brain only uses glucose as its energy source. However, when blood glucose level is abnormal, it causes some serious consequences. For instance, low-blood glucose phenomenon referred to as hypoglycemia can cause heart repolarization and induce cardiac arrhythmia causing sudden cardiac deaths. Diabetes, which can be viewed as a high-blood glucose level for a long period of time, is a dangerous disease as it can directly or indirectly cause heart attack, stroke, heart failure, and other vicious diseases. A solution for reducing the serious consequences caused by diabetes and hypoglycemia is to continuously monitor blood glucose level for real-time responses such as adjusting insulin levels from the insulin pump. Nonetheless, it is a misstep when merely monitoring blood glucose without considering other signals or data such as Electrocardiography (ECG) and activity status since they have close relationships. When hypoglycemia occurs, a fall can easily occur especially in case of people over 65 years old. Fall's consequences are more hazardous when a fall is not detected. Therefore, we present a Fog-based system for remote health monitoring and fall detection. Through the system, both e-health signals such as glucose, ECG, body temperature and contextual data such as room temperature, humidity, and air quality can be monitored remotely in real-time. By leveraging Fog computing at the edge of the network, the system offers many advanced services such as ECG feature extraction, security, and local distributed storage. Results show that the system works accurately and the wearable sensor node is energy efficient. Even though the node is equipped with many types of sensors, it can operate in a secure way for up to 157 h per a single charge when applying a 1000 mAh Lithium battery.
Chapter
Full-text available
The chapter presents aspects regarding the use of wearable electronic sensors, embedded in clothing for monitoring the health of the elderly and active living. The main goal of using wearable electronics is to provide continued assistance to patients in critical situations outside hospitals. The objectives are ubiquitous monitoring, transmission and storage of data from wearable sensors to perform signal analysis processes. To this end, data from several sensors, such as temperature, humidity, respiratory rate or pulse monitoring, can today be collected using simple electronics such as Arduino board. Because of the need to place the sensors in specific locations of the body, the link between the sensors and the board must be ensured by the use of flexible semiconductors — textile stainless yarns (filamentary and spun yarns).
Conference Paper
A wearable respiration monitoring system based on Respiratory induction plethysmography (RIP) using a new Polydimethylsiloxane-graphene (PDMS-graphene) compound tensile sensor is proposed. The manufacture procedure of this novel resistance-based tensile sensor is presented together with a wireless acquisition system. The proposed sensor shows a high sensitivity during stretching and a promising cyclic stability for continuous 3,600 cycles. Statistical analysis confirms a high correlation of respiratory rate monitoring between the proposed system and a medical-level instrument. This proposed system based on RIP, using a new PDMS-graphene compound tensile sensor can acquire respiratory signal unobtrusively with high accuracy and satisfactory user experience, and thus has great potential in home monitoring scenarios.
Article
Purpose Recent developments in wearable technologies have paved the way for continuous monitoring of the electrocardiogram (ECG) signal, without the need for any laboratory settings. A number of wearable sensors ranging from wet electrode sensors to dry sensors, textile-based sensors, knitted integrated sensors (KIS) and planar fashionable circuit boards are used in ECG measurement. The purpose of this study is to carry out a comparative study of the different sensors used for ECG measurements. The current challenges faced in developing wearable ECG sensors are also reviewed. Design/methodology/approach This study carries out a comparative analysis of different wearable ECG sensors on the basis of four important aspects: materials and methods used to develop the sensors, working principle, implementation and performance. Each of the aspects has been reviewed with regard to the main types of wearable ECG sensors available. Findings A comparative study of the sensors helps understand the differences in their operating principles. While some sensors may have a higher efficiency, the others might ensure more user comfort. It is important to strike the right balance between the various aspects influencing the sensor performance. Originality/value Wearable ECG sensors have revolutionized the world of ambulatory ECG monitoring and helped in the treatment of many cardiovascular diseases. A comparative study of the available technologies will help both doctors and researchers gain an understanding of the shortcomings in the existing systems.
Article
In this paper, we present a novel polymeric dry electrode that (1) changes its shape in a way that supports the electrode's contact with the skin and (2) that does not cause skin irritations or allergic reactions. For a polymeric substrate of electrodes, we have used the elastomer poly(dimethylsiloxane), which is known to be inexpensive, biocompatible, and amenable to micro-molding, and to have excellent gas and water permeability. We have established a process by which one can deposit a metal layer on the PDMS substrate, etch the electrode patterns chemically and with good resolution, and package the electrode so that it is easily wearable on the forearm. We measured the impedance according to the frequency change and compared the results with those of Ag/AgCl electrodes. Afterward, we measured the ECG signal and investigated possible artifacts caused by motion. For the feasibility of long-term monitoring, we examined the influence of surface electrodes on the skin after 7 days of ECG monitoring. In conclusion, our PDMS-based dry electrode measured the ECG signals with comparatively good fidelity, but showed better skin compatibility after long-term tests. We expect that our method for the production of PDMS-based dry electrodes will be broadly applicable to the field of ubiquitous biosignal monitoring.
Article
Textile electrodes and conductors are being developed and used in different monitoring scenarios, such as ECG or bioimpedance spectroscopy measurements. Compared to standard materials, conductive textile materials offer improved wearing comfort and enable long-term measurements. Unfortunately, the development and investigation of such materials often suffers from the non-reproducibility of the test scenarios. For example, the materials are generally tested on human skin which is difficult since the properties of human skin differ for each person and can change within hours. This study presents two test setups which offer reproducible measurement procedures for the systematic analysis of textile electrodes and conductors. The electrode test setup was designed with a special skin dummy which allows investigation of not only the electrical properties of textile electrodes but also the contact behavior between electrode and skin. Using both test setups, eight textile electrodes and five textile conductors were analyzed and compared.
Article
Techniques such as ballistocardiography (BCG) that can provide noninvasive long-term physiological monitoring have gained interest due to a growing recognition of adverse effects from poor sleep and sleep disorders. The noninvasive analysis of physiological signals (NAPS) system is a BCG-based monitoring system developed to measure heart rate, breathing rate, and musculoskeletal movement that shows promise as a general sleep analysis tool. Overnight sleep studies were conducted on 40 healthy subjects during a clinical trial at the University of Virginia. The NAPS system's measures of heart rate and breathing rate were compared to ECG, pulse oximetry, and respiratory inductance plethysmography (RIP). The subjects were split into a training dataset and a validation dataset, maintaining similar demographics in each set. The NAPS system accurately detected heart rate, averaged over the prescribed 30-s epochs, to within less than 2.72 beats per minute of ECG, and accurately detected breathing rate, averaged over the same epochs, to within 2.10 breaths per minute of RIP bands used in polysomnography.