This disclosure provides systems, methods and apparatus for assessing a surface using a piezoelectric element. In one aspect, the method includes applying a device to the surface, wherein the device includes at least one piezoelectric element and at least one EMS device, wherein the EMS device includes a conductive first layer separated from a conductive second layer, and wherein the piezoelectric element is electrically coupled to the EMS device such that a force applied to the piezoelectric element results in a voltage applied across the first and second layers.