Velocity Measurement using MEMS Ultrasonic Sensor for Non-invasive Blood Pressure Measurement

Abstract

We measured flow speed of a moving object in a water with Doppler effect using a MEMS ultrasonic receiver. This measurement is aimed for non-invasive blood pressure measurement. We proposed a wide frequency range receiver to measure both blood flow speed and vessel diameter at the same time in a blood vessel. Our sensor has a piezoresistive cantilever which is put on the boundary between air and liquid in a device. According to this structure, proposed receiver can measure acoustic waves from Hz to MHz order frequency, so that we can obtain blood flow speed (MHz order), and blood pressure change (Hz order) with the same device. On this paper, we measured flow speed ranging from 64.0 to 76.3 mm/s with 5.6 to 19% error.