Evaluation Of HF RFID for Implanted Medical Applications

Low cost HF RFID scanner subsystems that both deliver power and provide high bandwidth bidirectional communication channels have recently become available. These devices are anticipated to become ubiquitous in next-generation cell phones and enable a wide range of emerging e-commerce applications. This paper considers the use of HF RFID to power and communicate with implantable medical devices. We successfully communicated with ten transponders that were implanted at three locations within a human cadaver. In this paper, we present measurements collected from four of these transponders that represent a wide range of transponder sizes. We also describe how RFID for medical implantation requires significantly different privacy protections than previously investigated medical uses of RFID. Our experiments, which measure communication range, detect a strong sensitivity to the thickness of the insulator separating a transponder’s antenna from nearby tissue. This thickness can be tuned to achieve communication range similar to non-implanted transponders. This sensitivity can potentially be exploited to construct specialized implantable pressure sensors useful for a variety of applications.