A portable digital vault and related methods are disclosed that can provide a digital equivalent to the physical act of lending copyrighted content while also providing security to prevent copying of the content. The water-soluble photoactive compound is preferably a sulfonium salt. The anatomical constraints couple the propagation of cardiac contours according to their relative distance. A sourcedrain electrode, a planarization layer, and a pixel electrode are sequentially formed on the second dielectric layer, in which the sourcedrain electrode is electrically connected to the semiconductor layer through the first and second dielectric layers and the pixel electrode is electrically connected to the sourcedrain electrode through the planarization layer. The user’s device receives the identities and stores the received data in a log file.