Studies of a high-sensitive surface acoustic wave sensor for passive wireless blood pressure measurement

This paper develops a novel, high-sensitive surface acoustic wave (SAW) blood pressure sensor based on a 434.5 MHz resonator fabricated on an ST-cut quartz beam. First, 50 types of resonators with different layouts were designed, and then the sensitivity of the pressure sensors with different structures and sizes was simulated and calculated by using COMSOL Multiphysics software. Finally, a resonator with good performance was selected to fabricate a set of blood pressure sensors in different sizes, and these sensors were tested and evaluated through the use of both static and dynamic pressure measurements as well as animal experiments. For the sensor with a beam size of 10 mm x 1.3 mm x 0.3 mm, the results showed that in the range of 0-300 mmHg the pressure sensitivity was about 1.9 kHz/mmHg with good linearity, which matched well with the simulation results, additionally, the maximum non-linear curve fitting error was found to be less than 1 mmHg. Moreover, it could detect a pressure change as small as 0.1 mmHg. This sensor can be used to monitor blood pressure passively and wirelessly, and it will hopefully be applied in implantable devices for body pressure measurements in further research. (C) 2011 Elsevier B.V. All rights reserved.