Soft Tissue Testing
Testing soft tissues, such as skin, tendons, ligaments, and others, presents many challenges. Specimens of this type are delicate; hence they break at low forces. Gripping soft tissues can also be problematic given that these specimens are small, slippery, and compliant in nature. In addition, soft tissues are viscoelastic and often require accurate elongation or strain measurement to properly understand the material properties. Typically, in vivo conditions are needed to test soft tissues, which calls for the test to be performed at body temperature and in a hydrated state. This requires the testing equipment and fixture to be corrosion resistant and "waterproof" to avoid damaging the sensitive electronics of the testing system.
For testing at physiological conditions, the Instron® BioBath is an ideal solution for keeping a specimen fully hydrated in a saline solution and at 37°C. The BioBath uses a closed-loop temperature control measurement, which can be fed directly into the test system's software to accurately track specimen temperature, in addition to mechanical test data. Pneumatic grips are recommended for consistent clamping pressure that the user can vary up to 90 PSI. A high friction surface is often needed to grip slippery biomaterials to avoid specimen slipping. To avoid this, we recommend using a metallic high friction finish known as surfalloy on the grip face, but grit sandpaper is also a viable option. A water-resistant cover, such as the BioCoat, can help protect the system's electronics from damage in the case of spills or messy specimens.