Uniaxial Tensile Testing
During uniaxial tensile testing, the load is applied along a single specified direction of the bulk scaffold (comprised of individual fibres with distinct mechanical properties), while the specimen is free to contract laterally. For rectangular or dumbbellshaped samples, the load and displacement are measured. The stress vs. strain behaviour is calculated by normalising the force to the original cross sectional area (i.e. stress) and displacement to original gauge length (i.e. strain).
Biaxial Tensile Testing
For biological samples, adopting the uniaxial tensile test has limited value due to absence of freely contracting boundaries experienced by many tissues in situ. Many fibre reinforced soft tissues are subject to tensile loads along multiple directions. For this reason, biaxial tensile testing is more useful for measuring the mechanical properties of tissue-engineered constructs. Biaxial tensile testing allows for the measurement of material behaviour simultaneously along two orthogonal axes. This method is more accurate to characterise the mechanical function of scaffolds and tissues, which provides an approximate idea of in vivo loading [26, 27].