Power Transferring and Analogue Communication Approach for Implantable Devices

In this paper, we introduce a new approach of power transferring and communication for implantable devices to retrieve information from an implanted sensor. This approach originates in Radio Frequency Identification (RFID), and uses an analogue approach to communicate in order to decrease the complexity of implanted part and influence of attenuation, which requires coupling of coils. The design of power transferring mechanism consists of two parts, i.e., one reader and one label, which are similar to but actually different from those of RFID. To be specific, RFID uses electromagnetic fields to automatically identify and track the label attached to the object. In this work, the label can be implanted into a human body, and the reader is used to retrieve information from the label. The label is passive and the reader is active. When the reader transmits interrogator signals to the label, it will feedback the reader with two voltages, i.e., one is obtained with sensor and one without. The voltages are then used to locate the corresponding resistance of the sensor in a table. Experiment results of this work show that it is possible to retrieve information from a sensor placed on a passive label using load modulation approach in analogue manner. In addition, by computing the attenuation of human tissues to electromagnetic waves of different frequencies, we draw the conclusion that low frequencies are adaptive for the environment of human body.