The water content of leaves, their thickness, their density and other properties can now be determined without even having to touch them. A team of researchers from the CSIC Institute of Acoustics and the Agri-Food Research and Technology Centre (CITA) of Aragón has just presented an innovative technique that enables plant leaves to be studied using ultrasound in a quick, simple and non-invasive fashion.


Tomas E. Gómez, one of the authors of the study and researcher at the CSIC Institute of Acoustics, where a technique has been developed to analyse these parts of plants without touching them, explains to SINC that "The method involves establishing a silent dialogue with plant leaves, questioning them and listening to what they say".

The research, recently published in the journal, Applied Physics Letters, demonstrates that some properties of leaves such as thickness, density or compressibility can be determined with this method.

"The voice of the leaves itself is what gives us information about their status and their properties, all in an innocuous and silent way since communication is established by ultrasound, with above-audible frequencies", the scientist indicates.

The technique involves radiating the leaves with broadband ultrasonic pulses (between 0.2 and 2 megahertz), which are emitted through the air from portable devices. In doing so, the leaves start to vibrate and an ultrasonic sensor very similar to the transmitter detects the waves. The signal is then digitalised and the researchers analyse the resonance range, which enables the characteristics of the leaves to be assessed.

The entire process is done in a way that is non-intrusive to the plant. Until now, coupling fluids have been used between the ultrasound transmitter and the material being studied, as is in the case in medicine, for example, when gels or oils are applied to perform an ultrasound.