A method for tensile tests of biological tissues at the mesoscale

We describe a new technique for determining the tensile properties of biological tissues at the mesoscale. The procedure uses a calibrated magnetic interaction between a steel bead attached to the sample and a permanent magnet to apply a uniaxial tensile force, along with a simple video assay to monitor the sample extension and thus the strain. Our method fills a significant gap in the accessible range of both forces and strains and is useful for forces in the micro and milli-Newton range, and displacements in the range of hundreds of microns with strains of up to 200%. We give two examples of the mechanical characterization of tissues using our technique, employing it to characterize the elastic modulus of tubular and membraneous embryonic tissues from the chick.