An advertisement system that provides subscribers with the most relevant advertisements based on their individual purchase prediction of the various products and contextual information such as location, ongoing public events, festivals and personal events. A hydrogel containing immobilized binding particles is placed in contact with a carrier fluid containing analyte particles, which analyte particles diffuse into the hydrogel and bind with the immobilized binding particles. In some embodiments, the systems and methods of the present invention are used to evaluate the effectiveness of a particular treatment of a tissue region. The interface is useful for all types of devices with a rigid-to-flexible interface that needs to resist shear, tension, torsion, compression, or any disturbing steady-state or variable force or forces.