Fingertip Self-tuning RFID Antennas for the Discrimination of Dielectric Objects

Self-tuning RFID antennas are based on a new family of multi-state microchips capable of automatically adapting an internal reactive network in order to maximize the power harvested by the attached antenna when boundary conditions change. This concept can be applied to develop a radio-frequency fingertip-augmented device (R-FAD) to be used as dielectric probe on a finger to discriminate different kinds of materials and their discontinuities. When the finger, provided with a self-tuning epidermal tag, comes in touch with an object, the modification of the input impedance of the tag, related to the object's material, can be retrieved by an interrogating reader placed on the wrist. Possible applications concern the aid to impaired people suffering from peripheral neuropathy or eyesight deficiency, but even the inclusion in a robotic prosthesis. The modeling and design and characterization of the epidermal self-tuning tag is here presented for the first time and the idea is corroborated by some experimental tests with a system prototype.