A versatile biaxial testing platform for soft tissues

Uniaxial testing remains the most common modality of mechanical analysis for biological and other soft materials; however, biaxial testing enables a more comprehensive understanding of these materials' mechanical behavior. In recent years, a number of commercially available biaxial testing systems designed for biological materials have been produced; however, there are common limitations that are often associated with using these systems. For example, the range of allowable sample geometries are relatively constrained, the clamping systems are relatively limited with respect to allowable configurations, the load and displacement ranges are relatively small, and the software and control elements offer relatively limited options. Due to these constraints, there are significant benefits associated with designing custom biaxial testing systems that meet the technical requirements for testing a broad range of materials. Herein we present a design for a biaxial testing system with capabilities that extend beyond those associated with typical commercially available systems. Our design is capable of performing uniaxial tests, traditional biaxial tests, and double lap shear (simple shear) tests, in either a displacement or load control mode. Testing protocols have been developed and proof-of-concept experiments have been performed on commercially available silicone membranes and rat abdominal skin samples.