Microsensor techniques for cardiovascular systems

Abstract

Summary. Progress in semiconductor technology has been very fast in the last few years. One important fabrication process is the CMOS (Complementary Metal Oxide Semiconductor) process. This technology has been developed for the fabrication of electronic circuits, but is now also used for the fabrication of microsensors and microsystems by adding some compatible process steps. This contribution reports upon some examples for the application of CMOS-compatible physical microsensors with on-chip integrated read-out electronics in a cardiovascular ambient. Especially monolithically integrated pressure sensors and flow sensors for blood pressure and blood flow measurement are presented, representing the state-of-the-art techniques of CMOS-compatible surface micromachining and bulk micromachining. Due to the flexible design possibilities, the surface micromachined pressure sensor with a chip size of 0.7 mm × 7 mm or even smaller can be placed in a heart catheter with a diameter of 1 mm for blood pressure measurement in arterial vessels. Additionally a temperature sensor is integrated on the chip. In the same catheter application a flow sensor chip based on a hot-film anemometry principle measures blood flow dynamically with a fast response and low power consumption combined with small dimensions. A system with integrated circuits used for data acquisition with wireless data transfer of cardiovascular sensor signals from inside the body is also discussed.

Key Words:

• microsensor
• CMOS technology
• blood flow measurement
• blood pressure measurement
• heart catheter