A Strain Distribution Sensing System for Bone-Implant Interfaces Based on Digital Speckle Pattern Interferometry

Abstract

This paper aims to provide an effective measurement method for the distribution of deformations and strains focusing on the response to external loading of bone-implant interfaces. To achieve this target, a novel speckle interference imaging method is proposed by introducing phosphate buffer saline medium, in which the samples were completely placed into a phosphate buffer saline solution medium to stable the water molecules. The stability of interferometry imaging is analyzed by using the concepts of co-occurrence matrix and moment of inertia. A series of experiments to measure load-driven deformation and strain in the bone-implant interface was carried out, and the experiments results were analyzed and discussed. It shows that the proposed method is feasible and effective for the no-contact strain measurements of biomaterials in a physiological condition. The proposed strain distribution sensing system will contribute to evaluating computational simulations and improving selection of implant designs and materials.

Effect of the Speckle Size on the Quality of Speckle Pattern in DSPI System

“…The stability and the contrast of speckle pattern are the most critical indicators. The speckle stability directly determines the correlation of speckle images before and after strain, and affects phase image quality [31]. Speckle image contrast directly affects the quality of the speckle image [44].…”

“…Gaudette measured the surface deformations of epicardial heart based on the DSPI technology, in which he placed carbon-silicon particles on the heart surface to change the characteristics of the active surface [30]. Ping achieved the strain measurement of the bone active surface by introducing phosphate buffer saline medium imaging environment to reduce the influence of wet surface [31]. Although these methods can restrain the de-correlation of speckle patterns caused by the activity of the detected object to a certain extent, they are still not of universal significance.…”

New multiplexed system for synchronous measurement of out-of-plane deformation and two orthogonal slopes

“…[4,5] Specifically, DSPI is applied to measure the out-of-plane deformation, while DS is used to measure the slope of the out-of-plane deformation. [6][7][8][9] In theory, speckle interferometry can measure deformation and its slope in the nanoscale range. It is a research hotspot to combine the two techniques appropriately to develop a multiplexed system that can measure the out-of-plane deformation and its slope simultaneously.…”