Design and implementation of respiration and gait measurement system based on textile capacitive pressure sensor for ubiquitous healthcare service

다국어 초록 (Multilingual Abstract)

The basic objective of this dissertation is to design and implement a ubiquitous
health monitoring system based on textile capacitive pressure sensor. For long-term
health monitoring which is a ineviTable for mobility from the end-user perspective,
two types of textile capacitive pressure sensors were developed for respiration and
gait measurement from which respiration signal and gait signal analysis could be
monitored in a efficiency way.
In textile capacitive pressure sensor (TCPS), capacitance change by pressure
changes has been used for respiration and gait measurements.
Movements of the thorax and abdomen are occurred during respiration and
ground reaction forces are produced while the human is walking. Theses movement
and forces affected to conductive textile plates as a pressure which makes distance
changes between both conductive textile plates. Belt type TCPS (BTCPS)for respiration measurements and insole type TCPS
(ITCPS) for gait measurements are designed and developed. To verify the
characteristic and performance of sensors, the change of capacitance by change of
tensile strength and weights were measured and recorded.
In this dissertation, three types of experiments were performed using TCPS. One
is respiration measurement when the subject is in resting using BTCPS, another is
gait measurement with ITCPS when the subject walking in six different speeds on
the treadmill, and the other is respiration-gait measurement using both types of
TCPS when the subject walking in 9 different circumstances.
The results from each experiment are as follows:
1) Data was presented from the method comparison study in which respiration
signal measured with belt type textile capacitive pressure sensor was compared with
its measured with standard techniques (thermistor sensor) on 16 human subjects.
The result of data comparison showed 0.992 of Pearson’s correlation (P<0.001) and
the mean difference of two methods was -0.002 breath per minute (BPM) and its
standard deviation was 0.257 BPM. Also, limit of agreements were 0.504BPM as
upper limit and -0.501BPM as lower limit.
2) Data from six different treadmill speeds (1, 1.5, 2, 2,5, 3, 4 km/h) was
exhibited from a gait measurement with insole type textile capacitive pressure
sensor was compared with a pedometer and observations for step count and the data
was analyzed for monitoring gait pattern on 10 human subjects. The result showed
more accuracy rate (96%) in every treadmill speed than existing pedometers which
are not normally in accuracy in low speeds (1, 1.5, 2 km/h). also, through the
analyze of step time differences, stride time variability and coefficient of variance
(CV), gait pattern was monitored. From, all experimental results, it is confirmed that
all subject have different walking pattern and each subject has own walking style.
Therefore, with developed ITCPS, the change of gait pattern by health state could be
monitored. Also, it could be used for the person who is in rehabilitation therapy to
check improvement and to guide proper therapy. 3) Obtained signals from the simultaneous measurement of respiration and gait
during walking on treadmill with three different velocities and slopes, were analyzed
to find coordination between respiration and walking on 13 human subjects. The
coupling ratios of 1:1, 1:2, 1:3, 1:4, 3:2 and 5:2 are found and 2:1 ratio being
presented (51.28%) most often, which is same same result with other previous
studies. As a result of ANOVA test, increasing treadmill speed was affected to
degree of coordination. However, degree of coordination was unaffected by changes
in treadmill slope. The experimental result shows that the proposed sensor could
monitor abnormalities in human body through the change of coordination between
respiration and gait. Also, it could be used as a monitoring device for sports player
who need to find and train proper coordination between respiration and gait.
The current version of respiratory and gait signal monitoring system using TCPS
can successfully measure respiration and gait signals. It can be used in long term
respiration and gait monitoring without any discomfort. Also, it could be used in
daily activity monitoring, posture & walking examination and rehabilitation
monitoring. Especially, TCPS version of this technology offers a potentially
inexpensive implementation that could extend applications to consumer home
healthcare and mobile healthcare products.