Remote Powered Medical Implants for Telemonitoring

Chronic diseases like diabetes mellitus often require a permanent monitoring of vital signs. Especially the use of telemedicine will increase the quality of life for affected patients. Therefore, novel systems are necessary which are able to permanently detect and provide health status information. But these systems must not control patient´s life and should work autonomously. For this purpose, intelligent medical implants are well qualified. This work describes a system for wireless power supply and communication with medical implant applications. Monitoring vital signs will create a big amount of data. Therefore, high data rates are necessary provided by high operating frequencies which in turn lead to electromagnetic far-field conditions. In this case, high attenuation losses due to the permittivity of the human body ε_r have to be considered. Hence, high frequencies are not suitable for the transfer of energy into the human body. The presented concept is based on two different frequencies for power supply and data transmission. An independent development of both blocks is thereby possible. The power supply operates at a frequency of 13.56 MHz, using inductive coupling. Consequently, the human body does not affect the energy transfer. In contrast, the data transmission is operated at a frequency of the medical implant communication service (MICS) band. The elaborated system consists of a power supply unit, a data transmission unit, and a control unit. The implementation of the power supply and data transmission as well as associated theoretical basics are presented. Performed measurements demonstrate that the realized system is qualified for the use on human beings.