Developing a bio-mechanotronic probing system for estimating soft tissue Young’s modulus in vivo

Abstract

In many medical applications such as rehabilitation, clinical palpation, and manipulation of organs, it is important to characterize soft-tissue properties accurately. This paper presents a bio-mechatronic probing system that could be used for estimating soft tissue Young’s modulus in vivo. The system employs an electromagnetic spatial displacement sensor. The accuracy and reliability of the system were investigated. In addition, the effect of indentation rate on the variation of the values of the measured effective Young’s modulus was also studied. A series of elastomers with different Young’s modulus (ranged from 13.08 to 36.19 kPa) were assessed with both the probing system and a Hounsfield material testing machine. Intra-individual and inter-individual variations of the system were tested by five independent operators. The probing system was applied to assess the effective Young’s modulus of human body parts in vivo. Fifteen healthy female subjects with age of 22.5 ± 4.3 years old were included for the in vivo test. The system was shown to be highly accurate (R2 = 0.995) in comparison with the results obtained by the mechanical testing machine and had good reliability (intra-individual variation = 5.43%, inter-individual variation = 5.99%). The average effective Young’s modules of the region of umbilicus were 13.33 and 10.71 kPa for two different sites, respectively. Based on the results obtained, it is believed that this probing system was an accurate and reliable tool for rapidly assessing the mechanical properties of human body tissues in vivo.