An instrumented probe for mechanical characterization of soft tissues

Characterizing the mechanical properties of biological tissues is very important for research in biology, physiology and biomechanics, and even in clinical practice. Different techniques exist to perform accurate measurements of the mechanical parameters of tissues, but most instruments require that the biological sample is excised and prepared by drying and fixation. New and more versatile instruments capable of measuring the mechanical properties of different tissues directly, could be quite useful for many practical purposes, for example, in minimally invasive therapy. Microfabrication technologies are particularly suitable for developing miniature instrumentation for the measurements of soft tissues properties. We have designed and developed an apparatus purposely for characterizing the mechanical properties of tiny biological samples ex vivo, without any drying and fixation. This paper describes the main characteristics of the apparatus. The key component of the apparatus is a LIGA-fabricated and instrumented miniature probe which can grasp the soft tissue. In order to extract information on sample characteristics, a method has been devised for the identification of the probe-sample system. Using this apparatus, different samples of human skin have been tested ex vivo and successfully classified based on their mechanical properties.