Investigation of the mechanical frequency response of ovine renal tissue at low frequencies.

This study explores the mechanical properties of ovine renal tissue, focusing on resonance patterns at low frequencies. Using a universal tensile/compression testing machine, we examined the stress-strain behavior of the tissue under compression, revealing its non-linear viscoelastic characteristics. Dynamic Mechanical Analysis (DMA) and a dynamic shear rheometer were employed to measure the storage and loss moduli across various frequencies (0.01-10 Hz). The shear storage modulus ranged from 1 kPa to 48 kPa in the strain level of 0.5%, while the shear loss modulus varied between 2 kPa and 4 kPa. Experimental results showed no resonant behavior in the mechanical properties, including storage modulus, loss modulus, and tan delta, in both tensile and shear modes at frequencies below 10 Hz. A vibration test was conducted using a shaker to investigate the Frequency Response Function (FRF) of the kidney over the studied frequency range. The vibration tests revealed mechanical resonance in the kidney at approximately 3 Hz. A numerical modal analysis, conducted using COMSOL software, identified a natural frequency around 3 Hz, closely aligning with experimental observations. These findings suggest significant implications for understanding renal mechanics and developing medical applications.