Development of a handheld compression optical coherence elastography probe with a disposable stress sensor

Optical coherence elastography (OCE) is a functional extension of optical coherence tomography (OCT). OCE measures a sample's deformation under force stimuli. Compression is often used to generate the force stimuli in OCE. In this Letter, we report the development of a handheld quantitative compression OCE probe with a novel stress senor, dedicated to measuring the force. The stress sensor consists of a circular glass window and a metal ring which are connected with polyurethane spokes. This sensor is mounted on the tip of the OCT sample arm as an imaging window, so that the force applied to the sample through the window can be measured by detecting the window displacement from the OCT image. The force-displacement function was first developed through simulation on COMSOL Multiphysics and eventually calibrated experimentally. A phase-sensitive OCT technique was employed to measure both the window displacement and the sample deformation. The performance of an OCE probe with this stress sensor was evaluated on a two-layer phantom. The results show that it is extremely capable of measuring the sample Young's modulus. Finally, we successfully measured the elasticity of the human fingertip, indicating a good potential of this OCE probe for in vivo elastogram measurement on human skin.