Design and Evaluation of Piezoelectric Sensors for the Measurement of Blood Flow in Coronary Implants by the Ultrasonic Transit Method

Nowadays, there is a small number of biomedical systems to verify the quality of coronary transplants. They are especially expensive and their closed architecture makes them impossible to reproduce. Based on the method known as Ultrasonic Transit Time Flow Measurement (TTFM), ultrasonic piezoelectric sensors useful to evaluate the quality of coronary implants during cardiovascular surgery were designed. They show repeatability in their parameters; produce a homogeneous acoustic field, an adequate acoustic intensity in their emission and allow a flow reading with an uncertainty below 5 ml/min. It is shown that the plastic known as Rexolite offers less acoustic attenuation and better mechanical coupling for the sensors compared to epoxy resin, attaining a better performance. These sensors operate together with an electronic module governed by a reconfigurable FPGA type platform. Finally, it is shown that time intervals in the order of tens of picoseconds can be detected by our sensor (i.e., flow rates smaller than 5 ml/min).