Model-independent extraction of adhesion energy from indentation experiments

We present a model-independent method for extraction of adhesion energy from indentation experiments in which force, deflection, and contact area are measured. It is based on calculating the difference between external work supplied and stored strain energy, the deficit, which is assigned as work expended in opening (or closing) an interface. The critical step in the method is determination of the elastic indentation response without adhesion, using measured compliance. We show that this model-independent method accurately reproduces results obtained using the Johnson-Kendall-Roberts theory when it is applicable, and is particularly useful when an analytical contact mechanics solution is unavailable.