High-throughput shear test for soft adhesives

Soft-adhesive-based bonding technology has been widely adopted in emerging fields including flexible electronics, soft robotics, and tissue engineering. The failure behavior of soft adhesives depends not only on properties of the adhesive material but also on diverse parameters of the adhesive structures, such as adhesive thickness and adhesive angle. Systematically analyzing the effects of structural parameters on adhesive performance is crucial for the rational design of soft adhesive systems in engineering applications. Conventional testing methods are less efficient to generate large-scale experimental datasets required for such analysis. The present study develops a high-throughput shear test that enables the simultaneous measurement of adhesive strength for 180 specimens with different adhesive thicknesses and adhesive angles in a single test run. More than 800 data points of adhesive strength including scatter statistics are obtained through five runs of the high-throughput experiment. A semi-phenomenological failure criterion is established to fit the experimental data of failure strength in the tension-shear stress plane. Moreover, the failure morphologies of all specimens are analyzed through fractographic examination, and the effect of tension/shear ratio on the adhesive failure mode is presented.