The researchers from the Spanish National Research Council's Institute of Acoustics in Madrid and the Agri-Food Research and Technology Center of Aragon, Spain, said their findings demonstrate that some properties of leaves -- such as thickness, density or compressibility -- can be determined with the method.
The technique involves radiating the leaves with broadband ultrasonic pulses that 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 digitalized and the researchers analyze the resonance range, which enables the characteristics of the leaves to be assessed.
The team reported the study recently in the journal Applied Physics Letters. The scientists said they also took cuttings of some leaves to ascertain water loss over time, and they observed variations in leaf resonance and even water mass loss as little as 1 percent. The details of that research will soon be published in the Journal of Experimental Botany.