Biological Samples Measurement

About

BACKGROUND Quantification of the viscoelastic properties of soft tissue biopsies and fibrous protein gels is vital to the understanding of normal tissue devel- opment, wound healing, disease progression, and cell-mediated re- modeling engineered tissues.  Rheometers are well suited for charac- terizing the storage and loss modulus of such soft gels; however, standard geometries used in existing commercial instruments require relatively large, homogeneous samples to generate sufficient torque for accurate analysis of low stiffness materials.  Additionally, the analysis generally assumes isotropic linear viscoelastic behavior.  Newly formed tissues and biological protein gels such as blood clots are often small, soft, irregularly shaped, anisotropic, and difficult to handle.  Rheometry of tissue samples and other biological samples, such that the results of biopsies, is not commonly measured since the samples are incompati- ble with the conventional rheometers.  Accurate and sensitive viscoe- lastic characterization of small, irregularly shaped biological samples requires an extension to conventional rotational rheometry   SUMMARY Eccentric viscoelastic rheometry extends the utility of standard rotational rheometers for accurate and sensitiveviscoelastic characterization of small, irregularly shaped, or anisotropic samples and systems. The sample is radially offset from the center of a sample holding section of a conventional parallel plate rotationalrheometer. Imaging may be used to obtain geometrical and location properties of the sample, a polar moment of inertia for the sample and a complex modulus of elasticity for the sample.   ADVANTAGES Ability to analyze irregular shapes and anisotropic mate- rials Ability to analyze soft tissue and fibrous protein gels Reduction in sample volume used