IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 58, NO. 9, SEPTEMBER 2009 3079
A Hand-Held Indentation System for the Assessment
of Mechanical Properties of Soft Tissues In Vivo
Min-Hua Lu, Member, IEEE, Winnie Yu, Qing-Hua Huang,
Yan-Ping Huang, and Yong-Ping Zheng, Senior Member, IEEE
Abstract—Quantitative assessment of the mechanical properties
of soft tissues in vivo is required in both clinical and research
fields. This paper introduces a hand-held indentation system that
employed an electromagnetic spatial sensor as a displacement
transducer. The system was pen-sized, portable, and easy to con-
trol. The accuracy and reliability of the system were investigated.
The effect of indentation rate on the variation of the values
of the measured effective Young’s modulus was also studied. A
series of elastomers with different Young’s modulus (which ranged
from 13.08 to 36.19 kPa) were assessed with both the hand-held
indentation system and a Hounsfield material testing machine.
Intraindividual and interindividual variations of the system were
tested by five independent operators. The hand-held indentation
system was applied to quantitatively assess the effective Young’s
modulus of human body parts in vivo. Twenty healthy female
The system was shown to be highly accurate (R2= 0.99) com-
pared with the results obtained by the mechanical testing machine
and had good reliability (intraindividual variation = 5.43%,
and interindividual variation = 5.99%). The average effective
Young’s moduli of the region of umbilicus were 11.31 and
hand-held indentations system was an accurate reliable tool for
rapidly assessing the mechanical properties of human body tissues
Index Terms—Elasticity, electromagnetic spatial sensor, inden-
tation, soft tissue, ultrasound indentation, Young’s modulus.
The assessment of the mechanical properties is important not
only because of its ability to indicate the presence of a disease
or tissue disorder for diagnosis ,  but also due to its
NDENTATION is an effective method for assessing the
mechanical properties of soft tissues in vivo or in vitro.
Current version published August 12, 2009. This work was supported in
part by the Research Grants Council of Hong Kong under Grants PolyU
5245/03E and PolyU 5290/03E, by the Guangdong Natural and Science Foun-
dation (8451806001001751), and by the Hong Kong Polytechnic University.
The Associate Editor coordinating the review process for this paper was
Dr. Subhas Mukhopadhyay.
M.-H. Lu is with the Department of Biomedical Engineering, Shenzhen
University, Shenzhen 518060, China.
W. Yu is with the Institute of Textiles and Clothing, The Hong Kong
Polytechnic University, Kowloon, Hong Kong.
Q.-H. Huang is with the School of Electronic and Information Engineering,
South China University of Technology, Guangzhou 510641, China.
Y.-P. Huang is with the Department of Health Technology and Informatics,
The Hong Kong Polytechnic University, Kowloon, Hong Kong.
Y.-P. Zheng is with the Department of Health Technology and Informat-
ics, The Hong Kong Polytechnic University, Kowloon, Hong Kong and also
with the Research Institute of Innovative Products and Technologies, The
Hong Kong Polytechnic University (e-mail: firstname.lastname@example.org).
Digital Object Identifier 10.1109/TIM.2009.2016876
receivedFebruary12, 2008; revisedJune17, 2008.
indispensability in the construction of a biomechanical human
model for the evaluation of pressure garment , .
With the development of theoretical indentation solutions
, , indentation has widely been used to assess the mechan-
ical properties of the skin and subcutaneous tissue on the bony
substratum. The indentation properties of various soft tissues
in vivo has widely been reported in the literature, e.g., the very
thin layer of soft tissue that covers the anterior-medial tibia ,
the human forehead skin , forearms and thighs , residual
limbs , , fibrosis neck tissues , spinal tissues ,
, and plantar foot tissues , . Much information was
used for tissue characterization and diagnosis in the previous
studies. However, there are few data of the in vivo mechanical
properties of soft tissues covered by tight-fit wear, e.g., the
breast region, umbilicus region, and buttocks. This case makes
it difficult to model the interaction between these soft tissues
and the tight-fit wear.
Several generations of indentation instruments have been
reported for the assessment of tissue mechanical properties in
the literature. Indentation devices usually employ a load cell
to measure the loading force and a displacement transducer,
e.g., a linearly variable differential transformer –, a
potentiometer , or a laser distance monitor , to record
the tissue deformation according to the displacement of the in-
denter. However, the structures of these mechanical indentation
apparatuses were either complicated or large, which are not
convenient for in vivo tests. Portable and hand-held indentation
systems  have been developed and used for the assessment
of plantar-foot tissues and breast tissue. Furthermore, pen-sized
instruments with an ultrasound indenter  have also been
reported. The pen-sized, portable, and hand-held indentation
systems can efficiently be used to measure the mechanical
properties of soft tissues in vivo and are easy to control. The
ultrasound indentation system can measure the tissue deforma-
tion by tracking the ultrasound echo that was reflected from the
substrate bone. When the thickness of the soft tissue increases,
the attenuation of ultrasound will increase so that it will be
difficult for the ultrasound transducer to collect the echoes that
were reflected from the substrate bone. Hence, the ultrasound
indentation system is not suitable for the assessment of thick
tissues or tissues with gas.
In this paper, we report a new pen-sized hand-held indenta-
tion probe with a load cell and an electromagnetic sensor. Its
accuracy and reliability were investigated. The main use of this
new system would be to quantitatively measure the mechanical
properties of “thick” tissues, e.g., the breast, the buttocks, and
tissues in the umbilicus region.
0018-9456/$26.00 © 2009 IEEE
3080IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 58, NO. 9, SEPTEMBER 2009
Fig. 1. Diagram of the hand-held indentation system.
Hand-held indentation probe with a load cell and an electromagnetic
A. System Components
The indentation system consisted of a hand-held pen-sized
flat-ended indentation probe and a PC with software for data
acquisition (see Fig. 1). As shown in Fig. 2, the indenta-
tion probe was composed of a load cell (ELFS-T3M, En-
tran Devices, Inc., Fairfield, NJ, U.S.) and an electromagnetic
spatial sensor (MiniBird, Ascension Technology Corporation,
Burlington, VT, U.S.). The diameter of the rigid cylindrical
indenter was 9 mm. The indentation force was measured by
the load cell. The position and orientation of the indenter tip,
which was used to derive the indentation depth, was mea-
sured by the electromagnetic sensor. The spatial data, including
three translations and an orientation matrix, were transferred
from the control box of MiniBird to the computer through
its RS232 serial port. The sampling rate of MiniBird could
be as high as 100 Hz so that sufficient data can be col-
lected to improve the accuracy of the spatial information by
A program has been developed in Microsoft VC++ to collect,
process, and display the force and the spatial data in real
time during the indentation process. The acquisition of the
indentation force and spatial information was synchronized by
the program. All the data could be recorded in a file for further
B. Parameter Estimation
During the indentation, the probe was held perpendicular to
the tissue surface and moved along its axial direction up and
down. Thus, the indentation depth was calculated from the
moving distance of the electromagnetic sensor. The indentation
depth was controlled within 20% of the tissue thickness. Each
indentation was completed within 2 s to obtain an instantaneous
response of the tissue. The effective Young’s modulus E was
calculated using the model reported by Hayes et al. .
(1 − v2)
where F is the indentation force, v is the Poisson’s ratio,
d is the indentation depth, a is the radius of the indentor, h
is the thickness of the test tissue, and κ is a geometry and
material-dependent factor. Values of κ have been solved for
different values of the aspect ratio a/h (ranged from 0.2 to 2)
and Poisson’s ratio v (ranged from 0 to 0.5) ,  when
the indentation depth is kept as infinitesimal. Zhang et al. 
reported that κ was also dependent on the indentation depth,
and (1) was modified as
(1 − v2)
Zhang et al.  solved a new κ table using finite-element
analyses by considering the effect of large deformation. The κ
values that were reported by these researchers have widely been
used in the literature for the calculation of the effective Young’s
modulus. When a/h approaches to 0, i.e., h ? a, κ tends to
be 1. In this paper, the soft tissues were assumed to be nearly
incompressible with the selected indentation rate, i.e., Poisson’s
ratio v = 0.45.
C. System Calibration
The load cell was calibrated using an electronic balance with
a range of 5 N and at a sensitivity of 1 mN. The calibration
measurement indicated a highly linear response for the force
transducers (R2= 0.998). The positional accuracy of MiniBird
was tested using a 3-D translating device (Parker Hannifin
Corporation, Irvine, CA, U.S.) whose positional accuracy and
resolution was 1 μm . The 3-D translating device was used
to provide accurate positional recordings. The spatial sensor
of MiniBird was attached to the 3-D translating device via a
plastic arm with a length of 0.5 m. When the arm was moved
by the translating device, the spatial sensor was translated in
the same manner. During the movement of the spatial sensor, its
distance to the transmitter was within 30 cm. The locations of
the arm from the 3-D translating device and the positions of the
spatial sensor from MiniBird were simultaneously recorded at
ten different sites. The positional recordings were acquired only
when the spatial sensor was in a steady status; thus, an accurate
comparison between the readings from the spatial sensor and
those from the 3-D translating device can be conducted. In this
paper, we measured the distances between different sites and
compared the distance measurement results that were obtained
LU et al.: HAND-HELD INDENTATION SYSTEM FOR ASSESSMENT OF PROPERTIES OF SOFT TISSUES3081
from the position readings recorded by the two devices. Sup-
the real position measures in the space, the measurement error
(mean ± standard deviation) for the spatial sensor can be calcu-
lated. According to the ten sites, a total of 45 distances among
these sites were measured, and the accuracy of position mea-
surement by the spatial sensor was found at 0.06 ± 0.21 mm,
which indicates a good positional measurement performance
of the MiniBird device. For the measurements described in the
following sections, the distance between the spatial sensor and
the transmitter was kept as short as possible to achieve accurate
results (in a range of approximately 10–20 cm).
D. Accuracy Test for Measured Young’s Modulus
The accuracy of the new hand-held indentation system was
assessed by testing a number of elastomers (n = 4) with differ-
ent Young’s moduli using the hand-held probe and a Hounsfield
material testing machine (H10KM, Tinius Olsen, Ltd. U.K.).
The thickness of the elastomers ranged from approximately
20–30 mm. Ten serial tests were conducted on each elastomer
with different indentation rates by using the new indentation
probe. The elastomers were also tested with uniaxial compres-
sion under different compressing rates by using the Hounsfield
testing machine. The correlation between the effective Young’s
modulus of four elastomers, as determined both from the hand-
held indentation probe and the Hounsfield testing machine, was
E. Reliability Test
Both interindividual repeatability and intraindividual re-
peatability were tested. The interindividual repeatability test
involved five operators, identified as A to E. All the operators
were asked to use the hand-held indentation probe to test
the same phantom by using a constant speed (approximately
4 mm/s) for ten sequential trials. All the operators were blinded
to the results of the others’ assessments. The standard devi-
ation of the consecutive measurements of a single operator
was defined as the intraindividual variability of that operator’s
measurements. The variation of the mean of all operators was
defined as the interindividual variability. Two-way analysis of
variance (ANOVA; Minitab 14.1, Minitab Inc., PA, U.S.) with
the main factor-operator and the nuisance factor-trial was used
to analyze the variations of intraindividual and interindividual.
F. Effect of Indentation Rate
The indentation with the hand-held probe was manually
driven; thus, the rate of indentation cannot precisely be con-
trolled. The effect of variation in indentation rate on the values
of effective Young’s modulus was examined. Four elastomers
were tested using the following four indentation rates:
1) 2.5 mm/s;
2) 4 mm/s;
3) 5.5 mm/s;
4) 8.3 mm/s.
approximately 2 cm above the navel, and Site B was located at the level of the
crest of ilia, approximately 2 cm under the navel.
Test sites on the human body. Site A was located at the waist line,
These indentation rates were regarded as being within the
general range that manual indentation could be imposed .
ANOVA (Minitab 14.1, Minitab Inc., PA, U.S.) was carried out
to examine the effect of indentation rate.
G. In Vivo Test on Human Body
For the purpose of the design of shaping underwear and sim-
ulation, the Young’s modulus of the human body, particularly
the parts of breast, waist, abdomen, and hip, need to be exam-
ined. In this paper, two test sites were selected in the region
of umbilicus—above and under the navel—for approximately
2 cm, as shown in Fig. 3. Site was A located at the waist line,
and Site B was located at the level of the crest of ilia. Twenty
female subjects with the age of 21.1 ± 1.8 (mean ± SD) years
old, a body weight of 53.6 ± 7.3 kg, and a height of 155.6 ±
5.8 cm were tested. The whole-body water content and body fat
percentage were measured using a body composition analyzer
(Model BM-1, Labowell Corporation, Tokyo, Japan) for each
The indentation probe with the MiniBird sensor measures
the indentation depth by using the displacement of the indenter
during loading and unloading. To reduce the measurement
error in tissue deformation, the subject was asked to erectly
stand back to the wall and held her breath for 5 s during the
indentation, avoiding that the skin surface moved with breath or
the movement of the body during the process. All the subjects
followed this instruction.
The soft tissues at these two sites include the following
4) inner organs (e.g., stomach and intestines).
3082IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 58, NO. 9, SEPTEMBER 2009
Relationship between the Young’s modulus of the elastomers and
The new indentation system cannot measure the Young’s mod-
ulus of each individual tissue layer. On the contrary, only the
global mechanical properties of soft tissues were obtained.
The extracted Young’s modulus was a quantified value that
represents the overall tissue stiffness and was regarded as an
“average” value. Hence, it was an effective value. The thickness
of the tissues was defined as the distance from the skin surface
to the underlying spine. We found that it was difficult to obtain
this thickness by using a 3.5-MHz ultrasound scanning probe
whose penetration depth was approximately 75 mm. Instead of
using direct measurement, the body dimension from the front
to the back at sites A and B were measured for each subject,
and the values of most subjects were larger than 170 mm.
Considering the dimension of spinal vertebrae, it was assumed
that the tissue thickness at sites A or B was normally larger than
100 mm, and the aspect ratio a/h approached to 0.
Before each test on the human body, three to four trial tests
were performed at the testing site to precondition the soft tissue.
Then, each site was indented with five loading-unloading cycles
with an average indentation rate at 6.5 mm/s, and the effective
Young’s modulus was estimated from the data that were col-
lected at loading phases. During most of the indentation tests,
the indentation depth was controlled within 20 mm. With the
assumption that the tissue thickness was larger than 100 mm, it
was estimated that the indentation depth was controlled within
20% of the thickness. The Poisson’s ratio of the soft tissues
was assumed to be 0.45, i.e., nearly incompressible, which has
widely been used in the literature , .
Fig. 4 shows the relationship between the values of Young’s
moduli of four elastomers and the indentation rate. The mean
percentage standard deviation of the Young’s modulus E that
was obtained from the tests of four elastomers by using three
indentation rates was 7.4%. It was found that there was a slight
trend that the values of Young’s modulus increased when the
indentation rate increased, particularly for the elastomer labeled
was no significant effect of indentation rate on the values of
the Young’s modulus at a 5% level with p-value = 0.6. Hence,
it was concluded that the modulus of the elastomer was rate
insensitive within the range of 2.5-8.3 mm/s.
hand-held indentation probe by five operators (A–E). The graph illustrates the
relatively small intraoperator variation, as demonstrated by the maximum and
minimum Young’s modulus values. Moreover, the Young’s modulus readings
(median) did not show significant difference within individual operators.
Box plot of ten repetitive measurements of an elastomer with the
directly determined from the hand-held indentation probe and the Hounsfield
material testing machine at different indentation rates. The error bar indicates
the standard deviation of ten repetitive measurements.
Correlation between the Young’s modulus of the four elastomers as
Applying the hand-held indentation on elastomers, a coef-
ficient of variations was found intraindividually (5.43%) and
interindividually (5.99%) for repeated measurements of a phan-
tom by five independent operators. Fig. 5 shows the box plot of
the values of the Young’s modulus that was obtained from the
repetitive measurements. The two-way ANOVA also indicated
that neither operator factor nor trial factor had a significant
effect on the values of the Young’s modulus at a 5% level,
repeatability were quite good.
There was a very good correlation (R2= 0.99) between the
Young’s modulus of the four elastomers as directly determined
from the hand-held indentation probe and the Hounsfield ma-
terial testing machine (see Fig. 6). A Bland-Altman plot (see
Fig. 7) gave an indication of the size of errors between the
values of the Young’s modulus that was measured by the two
devices. The mean difference¯d was 0.48 kPa, and the standard
deviation s was 1.26 kPa. Based on the Bland-Altman plot,
most of the differences lied between¯d − 2s and¯d + 2s. It was
acceptable for clinical purposes .
Fig. 8 shows a typical force-deformation curve that was
obtained from the loading phase at a cycle of indentation
that was collected from Site A Subject 15. The data were
fitted well with linear regression (r > 0.99). The slope of
force/deformation was used as the value of F/d in the Hayes
model to estimate the effective Young’s modulus. Fig. 9 shows
LU et al.: HAND-HELD INDENTATION SYSTEM FOR ASSESSMENT OF PROPERTIES OF SOFT TISSUES3083
that was measured by the hand-held indentation probe and the Hounsfield
material testing machine.
Bland-Altman plot to test the agreement between the Young’s modulus
phase at a cycle of indentation that was collected from Site A Subject 15.
Typical force/deformation curve that was obtained from the loading
Effective Young’s modulus of the in vivo measurements on 20 female
the results of the in vivo measurements of soft tissues on
20 female subjects. The average effective Young’s modulus
of site A was 11.31 kPa, and it was 12.65 kPa for site B. It
was found that there was large variation in the values of the
effective Young’s modulus (32% for site A and 36% for site B)
within different subjects. However, there was a relatively strong
correlation (r = 0.66) between the effective Young’s modulus
of sites A and B. Furthermore, it was found that the effective
Young’s modulus was considerably correlated with the per-
centage of the whole-body water content with r = 0.52 and
was negatively correlated with the body fat percentage with
r = −0.57 (see Fig. 10). However, no significant correlation
between the effective Young’s modulus and the body mass
percentage of the whole-body water content with r = 0.52 and was negatively
correlated with the body fat percentage with r = −0.57.
index (BMI = body weight/height2with its unit kg/m2) was
Effective Young’s modulus was considerably correlated with the
IV. DISCUSSION AND CONCLUSION
The results of this paper showed that the hand-held indenta-
tion system was an accurate reliable tool for assessing the ef-
fective Young’s modulus of human tissues in vivo. The general
region of the manual indentation rate lied from 2 to 9 mm/s.
It was found that there was a slight trend that the Young’s
modulus increased when the indentation rate increased, which
means that the mechanical behavior of the elastomers may
have time-dependent phenomena. The whole indentation was
conducted very fast and completed within 2 s so that the in-
dentation response was regarded as the instantaneous response.
Hence, the Poisson’s ratio was assumed to be 0.45 to simu-
late the nearly incompressibility of both elastomers and soft
The Young’s modulus that was measured by the hand-held
indentation probe was found to be very well correlated with
that measured by a standard material testing machine. The
Bland-Altman plot indicated that the accuracy of the hand-
held device was suitable for the clinical use. The interindi-
vidual variations in the measurements were very small. These
variations were primarily due to the fluctuation in loading the
probe tip during the data collection and the indentation rate
control of each operator. Several groups have been developing
dynamic indentation systems, in which the indentation rate was
precisely controlled. However, they are limited in the constant
indentation depth, which makes them difficult to apply on soft
tissues with various thicknesses. Moreover, their reliabilities
need further investigation .
The soft tissues located in the waist and abdomens of the
female subjects were quantitatively assessed in vivo using the
hand-held indentation probe. The effective Young’s modulus
that the values of the effective Young’s modulus positively
correlated with the percentage of body water content and neg-
atively correlated with the body fat content, because water is
more difficult to compress, whereas fat is softer than the skin
and muscle. It is believed that the quantitative values of the
effective Young’s modulus of those body parts will be helpful
for the body simulation.
3084 IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 58, NO. 9, SEPTEMBER 2009
In this paper, we have used a simplified indentation model to
describe the load-indentation data that were collected by the
probe and to extract a single mechanical parameter, i.e., the
effective Young’s modulus. Although the simplified effective
tions, a more comprehensive modeling for the load indentation
is necessary for some more accurate analysis. It has been noted
in this paper that the values of the effective Young’s modulus
increased when the indentation rate increased for the tested
elastomers. This result may be due to the viscoelasticity of
the materials. Due to the viscosity, the reaction force of the
tissue depends on the deformation rate instead of the applied
deformation itself in the case of elasticity. Therefore, the value
of the effective Young’s modulus increased with the increase
in the indentation rate. It has been observed that the load-
indentation data are more affected in the unloading phase due
to the hysteresis that was caused by the viscosity. Therefore, we
have only used the data of the loading phase for the analysis to
reduce the effect of the viscosity. To fully compensate for the
effect of the viscosity, we can use a more comprehensive model
to describe the load-indentation data, such as the quasilinear
viscoelastic (QLV) model that we have used for ultrasound
indentation data for soft tissues , –. The QLV
model can provide the nonlinear and viscoelastic properties of
soft tissues by using curve-fitting procedures.
In conclusion, the results have demonstrated that this hand-
held indentation system is a potential tool for rapidly assessing
the stiffness of soft tissues in vivo. The system is portable and
easy to control. It can be used to quantitatively measure the
effective Young’s modulus of various human body parts, partic-
ularly those parts with thick soft tissues, such as the breasts,
waist, abdomen, hips, and thighs, for which it is difficult to
assess using the ultrasound indentation technique that we have
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Min-Hua Lu (S’05–M’06) was born in Jiangsu,
China, in April, 1977. She received the B.E. degree
in electronic engineering and information science
from the University of Science and Technology of
China, Hefei, China, in June 2001 and the Ph.D.
degree from the Hong Kong Polytechnic University,
Kowloon, Hong Kong, in 2007.
She is currently an Assistant Professor with the
Department of Biomedical Engineering, Shenzhen
University, Shenzhen, China. Her research interests
include the measurement and imaging of tissue me-
chanical properties using ultrasound or other modalities, ultrasonic character-
ization of articular cartilage, and finite-element simulation of biomechanical
analysis of soft tissues.
Winnie Yu received the Ph.D. degree from the Uni-
versity of Leeds, Leeds, U.K., in 1996.
In 2007, she was the Chair Professor of the Beijing
Institute of Clothing Technology. She is current-
ly with the Institute of Textiles and Clothing,
The Hong Kong Polytechnic University, Kowloon,
Hong Kong. She is also an Editor of the Research
Journal of Textile and Apparel and a Paper Reviewer
of textile journals. She has published more than
100 research articles and is the holder of seven
patents. She is the Inventor of “Soft Mannequin” for
bra pressure evaluation, which has commercially been licensed. In 2007, her
research team published a new “Bra Sizing System” using breast depth width
ratio, which has widely been reported by international press media and was
elected by Time Magazine as the Best Viewpoint in the 2007 Best Invention of
the Year. Her research interest is focused on 3-D body sizing and fit analysis.
Dr. Yu is a Fellow of the Textile Institute and the Hong Kong Institution
of Textile and Apparel. She received the Silver Award at the International
Exhibition of Inventors in Geneva in 2004 for her invention of the “Cubicam”
3-D body scanning system.
Qing-Hua Huang was born in Heilongjiang, China,
in November 1976. He received the B.E. and M.E.
degrees in automatic control and pattern recognition
from the University of Science and Technology of
China, Hefei, China, in 1999 and 2002, respectively,
and the Ph.D. degree in biomedical engineering from
the Hong Kong Polytechnic University (PolyU),
Kowloon, Hong Kong, in July 2006.
In 2002, he joined, as a Research Assistant, the
Rehabilitation Engineering Center of the PolyU,
where he became a Research Associate with the
Department of Health Technology and Informatics in 2006. After a two-year
postdoctoral fellowship with the Department of Electronic Engineering, City
University of Hong Kong, Kowloon, he joined South China University of
Technology,Guangzhou,China,in 2008 and is currently an Associate Professor
with the School of Electronic and Information Engineering. His research
interests include 3-D ultrasound imaging, medical image analysis, intelligent
computation for biomedical signals, and bioinformatics.
Yan-Ping Huang received the B.E. degree in elec-
tronic engineering and information science from the
University of Science and Technology of China,
Hefei, China, in 2002 and the M.Phil. degree in
biomedical engineering in 2005 from the Hong Kong
Polytechnic University, Kowloon, Hong Kong,
where he is currently working toward the Ph.D.
degree in the Department of Health Technology and
His research interest include the development of
novel ultrasound or optical methods for tissue char-
acterization and diagnosis, particularly in small tissues, such as skin and
cartilage, and the related instrumentation.
Yong-Ping Zheng (S’95–A’98–M’99–SM’06) re-
ceived the B.Sc. degree in electronics and informa-
tion engineering and the M.Eng. degree in ultrasound
instrumentation from the University of Science and
Technology of China, Hefei, China. He received
the Ph.D. degree in biomedical engineering from
the Hong Kong Polytechnic University (PolyU),
Kowloon, Hong Kong, in 1997.
After a postdoctoral fellowship in acoustic micro-
scope and nonlinear acoustics with the University of
Windsor, Windsor, ON, Canada, he joined PolyU as
an Assistant Professor in 2001 and was promoted as an Associate Professor
and a Professor in 2005 and 2008, respectively, with the Department of Health
Technology and Informatics and also with the Research Institute of Innovative
Products and Technologies. He is the holder of four U.S. and three Chinese
patents, as well as 12 patents pending, mainly in biomedical ultrasound.
His research interests include ultrasound elasticity imaging and measurement,
3-D ultrasound imaging, ultrasonic characterization of muscle and articular
cartilage, ultrasound instrumentation, and wearable vital sign sensors.