43rd Annual Symposium of the Ultrasonic Industry Association http://us-biomat.com/events-media/congresses/43rd-annual-symposium-of-the-ultrasonic-industry-association/ M.D. Fariñas and T.E.G. Álvarez-Arenas USBIOMAT, CSIC Madrid,Spain md.farinas@csic.es t.gomez@csic.es A method is presented for monitoring light/dark plant cycles based on the excitation and sensing of thickness resonances on the leaves, where the frequency-transmittance output curves show a clearly inverse relationship with the light intensity the plant receives. This is due to the variations induced in the plant activity (evapotranspiration) as response to variations in the light intensity. As a proof of concept, the technique has been applied to different plant types (monocots/dicots and deciduous/evergreen), different species, and genetically identical plants of the same species but grown under different environmental conditions.

1. MONITORIZATION OF PLANT LIGHT/DARK CYCLES 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
• Air-coupled and wide band ultrasonic technique is able to detect, in a non-destructive, non-invasive, non-contact and fast way, variations in the leaves thickness
resonances produced by changes in the plant that are originated by the plant response to environmental stimuli. Effective parameters like C33, density, ultrasonic
velocity, and attenuation are obtained from magnitude and phase spectra measurements of the first thickness resonance by solving the inverse problem.
• Decrease in light intensity (up to 93%) produces an increase in the leaf thickness resonant frequency (between 8-12%) as consequence of mechanical activity triggered in
plant leaves to reestablish water equilibrium what is highly dependent of the specie and its environmental development.
• Watering plants after a period of forced draught produces an increase in the thickness resonant frequency (between 5-30%) in variable time spans (10 – 400 minutes) as
result of activity, structure and arrangement of water transport channels between soil and the leaves.
A method is presented for monitoring light/dark plant cycles based on the excitation and sensing of thickness resonances on the leaves,
where the frequency-transmittance output curves show a clearly inverse relationship with the light intensity the plant receives. This is
due to the variations induced in the plant activity (evapotranspiration) as response to variations in the light intensity. As a proof of
concept, the technique has been applied to different plant types (monocots/dicots and deciduous/evergreen), different species, and
genetically identical plants of the same species but grown under different environmental conditions.
 Wideband & Air-Coupled
Ultrasounds
 Through Transmission
 Thickness resonances excitation
 Spectral analysis (phase and
magnitude)
 Data logger FieldLogger FL NOVUS
 Pulser/Reciever 5077PR Olympus
 Oscilloscope TDS5054 Tektronix
 Irrometer Watermark 200SS-V
 Photosynthetic Photon Flux SQ-
200-5, Apogee Instruments
𝒇
𝑴
𝒓𝒆𝒔
(kHz)
[± 15%]
Velocity
(m/s)
[± 5%]
∝ 𝟎/𝒇
𝑴
𝒓𝒆𝒔
(Np/m/kHz)
[± 7%]
Density
(kg/𝒎 𝟑
)
[± 5%]
Thickness
(µm)
[±15 %]
𝑪 𝟑𝟑
(MPa)
[±7 %]
Epipremnum aureum (I) 245 165 3.5 860 330 23
Epipremnum aureum (II) 260 200 2.3 915 390 37
Hibiscus rosa-sinesis 275 210 2.8 930 380 40
Dracaena marginata 645 320 1.7 890 250 92
Vitis vinifera 540 215 4.1 760 190 35
md.farinas@csic.es t.gomez@csic.es
EXPERIMENTAL RESULTS I
PLANT MATERIALEXPERIMENTAL SET-UP
0 20 40 60 80 100 120
-7
-6
-5
-4
-3
-2
-1
0
(fres
-f
M
res
)/f
M
res
(%)
Epipremnum aureum
Time (min)
f
M
res
= 202-266 kHz
0 50 100 150 200 250 300 350 400 450
-6
-5
-4
-3
-2
-1
0
(fres
-f
M
res
)/f
M
res
(%)
f
M
res
= 630-680 kHz
Dracaena marginata
Time (min)
0 10 20 30 40 50 60 70
-30
-20
-10
0
f
M
res
= 190 -335 kHz
(fres
-f
M
res
)/f
M
res
(%)
Hibiscus rosa-sinensis
Time (min)
0 20 40 60 80
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
(fres
-f
M
res
)/f
M
res
(%)
Vitis vinifera
Time (min)
f
M
res
= 540-560 kHz
Relative variation in the thickness resonant
frequency with the time after the plant is
watered (at time = 0).
Leaves After a Sudden Irrigation
Following a Force Drought Period
Evolution of the thickness resonant frequency of a Epipremnum aureum (I) leaf
during 4 days, Epipremnum aureum (II) during 4 days, and Dracaena marginata
during 3.5 days. PPF and ambient temperature measurements are also shown.
Evolution of the thickness resonant frequency of a
Hibiscus rosa-sinesis leaf during 3 days and Vitis
vinifera during 3.5 days. PPF and ambient
temperature measurements are also shown.
Monocotyledon Leaves Activity Variation Along the Daytime
Cycle
Dicotyledon Leaves Activity Variation Along
the Daytime Cycle
EXPERIMENTAL RESULTS II APPLICATIONS
Summary of the averaged leaf ultrasonic properties and their standard variation in each case found
by resolving inverse problem with one-layer model.
Hibiscus
rosa-sinesis
Vitis
vinifera
Dracaena
Marginata
a) Epipremnum aureum I:
grown without direct sunlight
b) Epipremnum aureum II:
grown under direct sunlight
 Agricultural industry
Water and irrigation optimization.
Monitor of plant development (biomass production).
Precise plant monitoring under special conditions:
Greenhouses
Extra terrestrial plant (crop/vegetables) production.
 Scientific tool
Study water relations in plants
Monitoring and test of the efficienty of fertirrigation systems
Precise monitoring of the response of genetically modified plants.
M.D. Fariñas, D. Sancho-Knapik*, J.J. Peguero-Pina*, E. Gil-Pelegrín*, T. E. Gómez Álvarez-Arenas