The development of a laser reflectance system to measure the cross-sectional area of soft tissues
Determination of the biomechanical properties of soft tissues such as tendons and ligaments is dependent on the accurate measurement of their cross-sectional area (CSA). Measurement of these tissues is problematic because they are easily deformed and possess complex cross-sectional shapes. To overcome these problems, a non-contact laser reflectance system (LRS) was developed. This system is designed to fit in a servo-hydraulic test machine and measures CSA by orbiting a laser transducer in a circular path around a soft tissue specimen held by tissue clamps. The system was validated using several machined metallic specimens, as well as different sizes of bovine tendons. The metallic specimens could be measured to within 4% accuracy, and the larger tendons to within 7%. The LRS was successfully used to measure the changing CSA of bovine tendons during uniaxial tensile testing. The LRS developed in this work represents a simple, quick, and accurate way of reconstructing complex cross-sectional profiles and calculating cross-sectional areas. In addition, the LRS represents the first system capable of automatically measuring changing CSA of soft tissues during tensile testing, facilitating the calculation of more accurate biomechanical properties.