Micro-pressure sensor for continuous monitoring of a ventricular assist device.

We have been involved in the development of a clinical ventricular assist device (VAD) system. Here, we report our investigation of in vitro and in vivo stability and sensibility of pressure microsensors. The sensors were mounted in the in-flow and out-flow cannulae wall to measure the left atrial and aortic pressures during VAD pumping. The pressure sensitive surface of the piezoresistive effect absolute pressure sensor was coated with a thrombo-resistant polymer, as was the inner surface of the cannulae of the VAD. In the in vitro and chronic animal experiments which were of more than a month duration, reliable stability and sensitivity, without any thrombus formation on the blood contacting surface of the sensors, and high sensitivity were observed. After chronic experiments, the sensitivity of sensors was reevaluated in the mock circulatory system as compared to reference values. The relationship between the output of the micro-sensors and the reference value was linear and correlated well.