Métodos de projeto para o acoplamento indutivo aplicado a implantes biomédicos

Abstract

In general, a biomedical implant can be enhanced whether the battery is replaced by another type of energy supply more suited to application. The enhancement can be still greater for the implant types that require an intensive use of the communication function. That is the case ofthe implant for physiological measurements in small animals, or telemeter implant. Inductive coupling poses as a convenient technique to provide the wireless communication and energization for a telemeter, besides other types of implants and devices for identification by RFsignals. In implants the inductive coupling is featured by a mutual inductance extremely reduced between the inductors. So, the system viability is conditioned to a suitable design method. In this work is carried out an investigation about the design methods for the inductive couplingapplied to a telemeter implant. Albeit with this focus, the methods developed in this work also can be used in others applications of the inductive coupling. The work establishes a design criterion about the relative positioning of the coupled inductors, which is based on the telemeter implant. It is discussed the mathematical formulationfor evaluation of the inductor parameters, in accord with the adopted modeling. This modeling is validated by means of measurements.The steps for the design of the inductive coupling circuits are discussed. The geometrical parameters scanning method is introduced and its limitations are presented. A complete achievement of the step is demonstrated and its results are evaluated. The step concerning the design of components for the circuits is presented in accord with four methods developed. For all methods the goals are about the positioning of the maximum in the power transfer characteristic and the bandwidth required in the communications. The methods are based on mathematical expressions deduced in analyses carried out for the power transfer and bandwidth in the inductive coupling circuits It was done also the implementation of a temperature monitoring system, whose sensorhas energization and communication based on inductive coupling. It is introduced a technique that allows better quality in the measurements for this type of sensor. Lastly, the results in experiments for evaluation of the sensor power consumption, as well as system adjust andvalidation, are presented.