A telemetric measurement system for flow diagnostic after bypass surgery

In medical applications minimal invasive techniques become more and more important. This paper is focused on the results of vascular flow measurements based on micromachined acceleration sensors. A telemetry circuit will be designed to transmit energy to the system and transmit data from it. The sensors were placed outside on artificial blood vessels. With special prepared measuring equipment we have varied the flow through elastic flexible tubes. The tubes were narrowed to different levels to simulate different states of a stenosis. The duty cycled output signals of the acceleration sensors modulates the amplitude of an analogue carrier frequency. The demodulator in the receiving module rebuilds the transferred sensor signals which are evaluated by a microcontroller.