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M.D. Fariñas, D. Sancho-Knapik*, J.J. Peguero-Pina*, E. Gil-Pelegrín*, D. Saco^, T. Gómez Álvarez-Arenas
CHARACTERIZATION OF THE CELLULAR STRUCTURE OF MESOPHYLL TISSUES OF
PLANT LEAVES USING AIR-COUPLED ULTRASONIC SPECTROSCOPY
US-BIOMAT, Ultrasonic and Sensors Tech. Dept. ITEFI, CSIC, Serrano 144, 28006, Madrid, Spain *Unidad de Recursos Forestales. CITA, Gobierno de Aragón. Zaragoza, Spain ^Facultad de Farmacia. Universidad Complutense de Madrid. Madrid, Spain
Examples: Platycerium bifurcatum Phormium tenax Aspidistra elatior
Examples: Epipremnum aureum Vitis vinifera Hedera helix Prunus laurocerasus Acer platanoides Ligustrum lucidum
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8
-80
-75
-70
-65
-60
-55
-50
-45
-40
-35
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8
-6
-5
-4
-3
-2
-1
0
MAG
Ma
gn
itu
de
(d
B)
Ligustrum Lucidum II
FAS
Ph
ase
(ra
d)
Frequency (MHz)
• Leaves effective parameters like C33, density and ultrasonic velocity, and attenuation are obtained from magnitude and phase spectra measurements
of the first thickness resonance by solving the inverse problem.
• In some cases, a distortion of the resonance pattern is observed. This distortion can be conventional or anomalous, two explanations are provided
for the second case: heterogeneous Mesophyll structure or anomalous wave dispersion similar to that found in other flexible foams
A non-contact and through transmission ultrasonic technique is proposed for the characterization of the cellular structure of the Mesophyll tissues in plant leaves. The mechanical properties of the tissues are extracted from measurement of the thickness resonance spectra by solving the inverse problem. Furthermore, the second order of thickness resonance is also measured. Compared with model predictions, the results show a distortion of the frequency pattern of the spectra of the first two orders of the thickness resonances. The observed distortion degree is variable and experimental evidences suggest, so far, that it may depends on the tissues layered microstructure, cell shape, cell wall rigidity and turgor pressure, among others.
HOMOGENEOUS (MONOCOT) TISSUE, DISPERSIVE (ANOMALUOS)
HETEROGENEOUS (DICOT) TISSUE ALSO DISPERSIVE (ANOMALOUS)… (?)
0,2 0,4 0,6 0,8 1,0 1,2 1,4
-70
-65
-60
-55
-50
-45
-40
0,2 0,4 0,6 0,8 1,0 1,2 1,4
-2,4
-2,2
-2,0
-1,8
-1,6
-1,4
-1,2
-1,0
-0,8
-0,6
Cinta Hall
MAG
Ma
gn
itu
de
(d
B)
FAS
Ph
ase
(ra
d)
Frequency (MHz)
MOTIVATION
Arm
on
ic D
isto
rsio
n
< 1 EXPERIMENTAL SET-UP
Wideband & Air-Coupled Ultrasounds Through Transmission Thickness resonances excitation Spectral analysis (phase and
magnitude)
v [m/s] ρ [kg/m3] th [µm] C33 [Mpa] α [Np/m]
Populus x. euroam. 305 722 223 67 1686
Ligustrum l* 353 1038 692 130 225
Vitis v. 317 927 238 93 1093
Epiprenmum a. 205 821 414 35 520
Nerium o. 284 892 565 72 698
I. Analysis f1
Acoustically Layered Meshophyll:
• In many cases agree
with Mesophyll structure
Frequency distortion < 1
Classical wave dispersion
Frequency distortion > 1
Two alternative solutions:
II. Analysis f1 and f2
Anomalous Low Frequency Wave Dispersion:
• Both velocity and attenuation increase with frequency
• Similar behaviour observed in soft foams in contrast to rigid foams
A B
Soft and dispersive foam
Rigid and non-dispersive foam
[email protected] [email protected]
Leaf cross section
-60
-40
-60
-40
-60
-40
1 2 3 4 5 6
-60
-40
Ligustrum Lucidum *
Vitis Vinifera
Magnitude (
dB
)
Epipremnum Aureum
Normalized Frequency
Nerium Oleander
-60
-40
Populus x. euroam.
> 1
-
De
gre
e o
f ar
mo
nic
dis
tort
ion
(>1
)
-
+
Degree of armonic distortion (>1) - +
Examples: Populus x euroam. Ligustrum lucidum * Vitis vinifera Eucalyptus
0,0 0,2 0,4 0,6 0,8 1,0 1,2
-70
-60
-50
-40
0,0 0,2 0,4 0,6 0,8 1,0 1,2
-1,5
-1,0
-0,5
0,0
0,5
1,0
1,5
MAG
Ma
gn
itu
de
(d
B)
Ligustrum Lucidum I
FAS
Ph
ase
(ra
d)
Frequency (MHz)
QUASI- HOMOGENEOUS (DICOT) TISSUE NON-DISPERSIVE
Examples: Dracaena marginata
HOMOGENEOUS (MONOCOT )TISSUE, NON-DISPERSIVE
0,2 0,4 0,6 0,8 1,0 1,2 1,4
-60
-55
-50
-45
-40
0,2 0,4 0,6 0,8 1,0 1,2 1,4
-1,2
-1,0
-0,8
-0,6
-0,4
-0,2
0,0
0,2
0,4
0,6
Dracaena Marginata
MAG
Ma
gn
itu
de
(d
B)
FAS
Ph
ase
(ra
d
Frequency (MHz)
CLASSIFICATION OF THE TISSUES ATTENDING TO THEIR ACOUSTIC RESPONSE
QUASI- HOMOGENEOUS (DICOT)
TISSUE , DISPERSIVE (ANOMALOUS)
?
Degree of Mesophyll heterogeneity - +
De
gre
e o
f an
om
alo
is d
isp
ers
ion
+
-
The acoustic properties of the mesophyll of a leaf depends not only on the species but also on the maturity of the tissue, the
environmental conditions where it grows , the turgor pressure…
?? EXPERIMENTAL RESULTS