A class of cationic, polyphemusin-like peptides having antimicrobial activity is provided. This configuration makes it possible to avoid an unauthorized use of the authentication system. An x-ray detector adapted to receive x-rays from the at least one inspection region of the document and to generate a corresponding detector response. Potential applications of this technology include charging consumer electronic devices, developing hermetically sealed devices for extreme environments, and less invasive transcutaneous energy transfer systems.