Biomedical Engineering Reference
In-Depth Information
Fig. 5.13 a MR-compatible loading device (schematic), b buttock loaded with a cylindrical
indenter head, c indenters with microperfusion sensor, d and e loading scenario at the buttocks
(schematic)
5.2.2 In Vivo Experiments I: Elasticity
5.2.2.1 Force-Displacement Data
Experimental Set-Up: To investigate the material behaviour of the skin-fat-
muscle compound in the gluteal region, an MR-compatible loading device was
developed, Fig.
5.13
a, by which mechanical properties of the human body were
gathered in vivo, Fig.
5.13
b. The apparatus ensured defined and reproducible
loading and unloading and was compatible with the deployed MRI-device in terms
of material (PVC, AL) and dimensions (H 9 W 9 D: 350 9 540 9 300 mm).
Loading was applied via a cylindrically shaped indenter head (Ø25 mm) with a
head corner radius of 1 mm, equipped with a 200 N force transducer (1 mV/
V 9 3 %). The indenter displacement was measured via an incremental TTL-
rotary encoder (1,024 ppr) situated in the upper part of the apparatus. To localise
the position of the indentation axis in the MRI-environment for reproducibility in
the FE-modelling process, tablets with a high fraction of sodium hydrate were
incorporated into the indenter head, conferring a clearly detectable signal. To
