Noncontact and noninvasive study of plant leaves using air-coupled ultrasounds

Abstract

Plant leaves are studied by the analysis of the magnitude and phase spectra of their thickness mechanical resonances. These resonances appear at ultrasonic frequencies and have been excited and sensed using air-coupled ultrasounds. In spite of the complex leaf microstructure, the effective medium approach can be applied to solve the inverse problem, at least in the vicinity of the first thickness resonance. Results suggest that these resonances are sensitive to leaf microstructure, composition water content and water status in the leaf.

Espectroscopía Ultrasónica Resonante Sin Contacto y su Aplicación al Estudio de Tejidos Vegetales en Estructura Multicapa = Non-Contact Resonant Ultrasound Spectroscopy and its Application to Study Multilayered Vegetal Tissues

“…Hence, what we really obtained are effective leaf properties. This approach has been applied before for other plant leaves with meaningful results (Álvarez-Arenas et al, 2009a;.…”

“…1b) had a well-defined palisade parenchyma with a close-packed row of relatively larger cells (50-75 mm). As an initial characterization of these materials, 10 different leaves of each species were ultrasonically characterized at full turgor from analysis of the magnitude and phase spectra of the first thickness resonance in the transmission coefficient using the procedure proposed by Alvarez-Arenas et al (2009a). For V. vinifera and E. aureum leaves, such measurements had already been reported by .…”

“…On the other hand, the leaf grown with direct sunlight exposure (Figure 1.b), present a well-defined palisade parenchyma with a close packed row of relatively larger cells (50-75 μm). As an initial characterization of these materials ten different leaves of each species were ultrasonically characterized at full turgor using the procedure proposed by Álvarez-Arenas et al, (2009a). Averaged leaf parameters so obtained are summarized in Table 1.…”

“…Conventional ultrasonic had been used before in plant leaves ; aircoupled ultrasound and spectral analysis of leaves thickness resonance was first proposed by Álvarez-Arenas et al, (2009aÁlvarez-Arenas et al, ( , 2009b. Later, , 2011 established a link between leaf physiologic and ultrasonic properties.…”

“…Different sonic and ultrasonic techniques has also been employed to the study of plant leaves (Miller,1979;Zebrowski, 1992;), though air-coupled ultrasonic techniques in a through transmission configuration has only been recently applied to excite and sense thickness resonances in plant leaves (Álvarez-Arenas et al, 2009aand Fariñas et al, 2013a. From the analysis of the magnitude and phase spectra of the first order resonance it is possible to extract the effective mechanical properties of the whole leaf in the direction normal to the leaf plane.…”