Andreas Hennig

Analysis of Power Absorption by Human Tissue in Deeply Implantable Medical Sensor Transponders

The use of sensor transponder systems inmedicine opens valuable possibilities in therapy and diagnostics. This chapter is about physical effects by the use of sensor transponder technology for medicine applications, especially for deeply implanted passive powered sensor transponders. This chapter will inform about present and future applications. The influence of human body on the energy transmission in a sensor transponder system is shown. The dielectrical properties of human tissue are discussed. A way how to estimate losses in an analytical way and with the use of a 3D FTDT method is presented. Finally, a design example of an energy transmission for a sensor transponder is shown with a calculation of the optimal frequency and experimental results.

A data transmission technique for passive sensor-transponders in medicine

The use of sensor-transponder technologies particularly in medical applications opens valuable possibilities in therapy of human cardiovascular system diseases, e.g. cardiac insufficiency. The application presented here is representative for future applications, where the use of miniaturized passively-powered sensor-transponder systems with high read range is relevant. In the past, load-modulation was developed as a simple technique to transmit data from low-cost ID-transponders to a reader. This technique can be considered as suboptimal for the given challenges in the presented medical and other possible high-demanding applications. Higher read ranges and small antenna dimensions are necessary. In consequence new techniques, especially for data transmission, have to be developed. First of all, the limitations of the load-modulation technique are analyzed. Conventional solutions are then discussed. It is shown that existing solutions could not be used for this specific and future applications. A new data transmission technique called ¿frequency conversion¿ is presented. This technique allows data transmission over a greater distance. Measurements in a practical implementation verifiy the performance of this technique.

Sensor transponder system for cardiovascular diseases

By the use of sensor transponder technology, the therapy of heart failure can be significantly improved. Through continuous monitoring of the heart an optimal adaption of drug dosage is possible. First, the state of the art and examples of existing solutions are outlined. A novel sensor transponder system is presented that enables high read range and small antenna dimensions and thus allows direct implantation into the heart.