Agarose as a tissue mimic for porcine kidney at the micro-length scale

Agarose gels are frequently utilized to simulate tissue. This study aimed to find an appropriate agarose concentration that matches the mechanical characteristics of pig kidney at the micro length scale and compare these to macro-scale properties. For all agarose samples and porcine kidneys, the shear storage modulus and loss modulus were measured at the micro-length scale using nanoindentation measurements with a 100 μm diameter probe, for frequencies from 10 Hz to 110 Hz. Measurements at the macro-length scale were carried out with a rheometer from 0.1 Hz to a maximum of 9.5 Hz at a shear strain amplitude of 0.1 % and fit to a fractional derivative mechanical model. The storage modulus at the micro-length scale was higher by factor of 1.2-70 than the storage modulus at macro-length scale in kidney samples and agarose (depending on agarose concentration), which was linked to gel and tissue microstructure. An agarose concentration of 1.2 % best fitted the kidney tissue properties at microscale.