Pressure, flow and oxygen saturation sensors on one chip for use in catheters

This paper presents a combination sensor chip, which is to be fitted to a catheter for use in intervention therapy. The chip contains an absolute pressure sensor, a thermal flow sensor and a colour sensor to determine respectively: blood pressure, blood flow velocity and oxygen saturation in one location at the same time. The sensors where fabricated using epi-micromachining. Change in absorption at wavelengths 660 nm and 800 nm due to the oxygenation of the blood are measured using two stacked photodiodes that serve as a colour sensor.