Feasibility using a compact fiber optic Sagnac interferometer for non-contact soft tissue surface mechanical wave speed detection.

The Sagnac interferometer offers distinct advantages in vibrational wave detection. In this study, an air-coupled transducer and a compact fiber-optic Sagnac interferometer were developed for non-contact elasticity characterization in biological tissues. Given the challenge of limited light collection by a compact fiber optic Sagnac interferometer in biological tissues, this study aims to explore the potential of using a compact Sagnac interferometer to measure vibrational waves in biological tissues. The speeds of the generated vibrational surface waves in tissue-mimic phantoms were measured. Measurement errors caused by cross-correlation wave tracking were analyzed, and the performance of the integrated system was characterized. The results demonstrated the effectiveness of the integrated system and the cross-correlation algorithm in tracing the speed of vibrational surface waves in tissue-mimicking phantoms. They suggested potential applications for the non-invasive, contactless characterization of the mechanical properties in soft biological tissues.