Katherine Kerr is a rising junior at Purdue University, majoring in Biomedical Engineering. She is working in Dr. Paul Janmey’s lab, measuring the shear rheology of soft biomaterials.
Viscoelastic Properties of Tofu as a Phantom for Liver Disease Diagnosis
Liver disease is the cause of approximately two million deaths globally each year. Many liver diseases, such as liver fibrosis, are characterized by alterations in the mechanical properties of liver tissues. Magnetic resonance elastography (MRE) provides a noninvasive tool to diagnose and monitor liver disease by measuring the mechanical properties of tissues. To ensure accurate evaluations of tissue properties, materials called phantoms are often used to calibrate an MRE device. Traditional phantoms, such as polymeric gels, can be expensive, difficult to produce at large scales, and lack complex structures associated with liver tissue. Tofu offers a phantom candidate that is cheaper and easy to manufacture. In this work, the rheological properties of two types of commercial tofu, varying in firmness, were studied at different compression levels, making use of a home-made torsion pendulum. The pendulum was compromised of two aluminum plates, a labjack to which the tofu was fixed, and a rotary motion sensor. A cylindrical tofu sample was sandwiched between the labjack and plates. The plates were rotated by a small angle and then released. The subsequent oscillation angle was measured and used to infer the viscoelastic properties of tofu at various compression levels up to fifty percent. It was found that both types of tofu exhibited compression stiffening and shear softening properties, being qualitatively similar to liver properties. Our results suggest that tofu could be used as a tissue mimicking phantom to calibrate and validate MRE results.