Non-contact acoustic method to measure depth-dependent elastic properties of a kiwifruit

TL;DR

This study introduces a non-contact ultrasonic method using laser technology to measure depth-dependent elastic properties of kiwifruit, revealing how these properties change with ripeness and differ between fruit layers.

Contribution

It presents a novel non-contact acoustic measurement technique combined with theoretical modeling to assess internal elastic properties of kiwifruit.

Findings

Surface and direct wave velocities increase with ripeness.

Elastic moduli vary between inner and outer fruit layers.

The method enables non-invasive, depth-dependent property estimation.

Abstract

The mechanical properties of a kiwifruit are investigated via non-contact acoustic measurements. Transmitted ultrasonic waves are measured using a static laser source and a rotating laser ultrasound detector. The measurements enable observation of a low-frequency surface wave and a higher frequency direct wave; combined with seismology-inspired theoretical modeling, these measurements enable estimation of several elastic parameters for inner and outer fruit flesh layers. Results indicate that the surface and direct wave velocities and the bulk and Young's moduli all evolve with fruit age/ripeness, while only the direct wave velocity and bulk modulus differ significantly between outer and inner fruit layers.