A Thermoacoustic Imaging System for Noninvasive and Nondestructive Root Phenotyping

Information about the root system architecture of plants is of great value in modern crop science. However, there is a dearth of tools that can provide field-scale measurements of below-ground parameters in a non-destructive and non-invasive fashion. In this brief, we propose a multi-modal, non-contact thermoacoustic sensing system to address this measurement gap and discuss various system design aspects in the context of below-ground sensing. We also demonstrate the first thermoacoustic images of plant material (potatoes) in a soil medium, with the use of highly sensitive capacitive micromachined ultrasound transducers enabling non-contact detection and
$cm$
-scale image resolution. Finally, we show high correlation (adj.
$R^{2} = 0.95$
) between the measured biomass content and the reconstructed thermoacoustic images of the potato tubers.